presentation on restoring and reproduction of paintings

IELTS Listening Online Practice Test – 33

IELTS Listening Online Practice Test: This is the 33 rd  test of our ‘ LISTENING Series ’. All tests are based on real exam patterns and correspond to the actual difficulty level you may find in the IELTS.

This test module is crucial from an immigration perspective and is divided into  four sections  – Sections 1, 2, 3 and 4.

Section 1  is a conversation between the organiser of a Short Film Competition and a man who is interested in taking part in this event.

Section 2  is a man talking to a group of volunteers who are involved in work in an area called Eskdale Wood.

Section 3  is a discussion between two art history students on restoration and reproduction of old paintings.

Section 4  is a presentation given by a student on challenges of living in a space.

You can  check your answers  &  calculate your band scores  at the end of this test. It is strongly advised to print the sample answer sheet and mark your answers on the sheet as well.

The speakers may suggest different possibilities or change their minds during the discussion. Pay careful attention to their final wording about the topic in IELTS online Listening Practice Test.

Questions 1-10

Complete the notes below.

Write ONE WORD AND/OR A NUMBER for each answer.

Questions 11-12

Choose TWO letters, A-E.

Which TWO tasks will volunteers be required to do at Eskdale Wood?

Questions 13-14

Which TWO things must volunteers bring with them?

Questions 15-20

Complete the flow-chart below.

Choose SIX answers from the box and write the correct letter, A-H, next to questions 15-20.

TO TAKE PART IN THE BIRD COUNT

set up a (15) …………………………. for a mobile app.

decide on a (16) …………………………. for the day of the bird count.

organise a (17) …………………………. for support.

ensure everyone has access to a (18) …………………………..

agree on a (19) …………………………. for observed birds.

submit a (20) …………………………. with your collected data.

Questions 21-25

Choose the correct letter – A, B or C.

PRESENTATION ON RESTORING & REPRODUCING PAINTINGS

21) The students agree that the introduction to their presentation should include …

A. reasons why paintings need to be restored.

B. examples of poor restoration work.

C. a general description of what restoration involves.

22) When the students visited the museum, they were surprised by …

A. the time it took to restore a single painting.

B. the academic backgrounds of the restorers.

C. the materials used in restoration work.

23) What does Oliver say would put him off a career in art restoration?

A. the reaction of the owners of a painting.

B. the possibility of working in dangerous conditions.

C. the requirement to be able to draw very well.

24) What do the students agree about the restored Dutch landscape painting?

A. It shows how taste in art varies amongst different people.

B. It is an example of a work that was once undervalued.

C. It demonstrates how cleaning techniques have greatly improved.

25) What is Oliver’s attitude to the digital reproduction of famous paintings?

A. It requires a great deal of skill.

B. There is something dishonest about it.

C. It makes art accessible to more people.

Questions 26-30

What challenge did the Factum Arte team face with reproducing the following paintings?

Choose FIVE answers from the box and write the correct letter, A-G , next to questions 26-30.

Questions 31-40

Write ONE WORD ONLY for each answer.

THE CHALLENGES OF LIVING IN A SPACE

IELTS Listening Online Practice Test – 33 Answer Key

• MAY 15/15 MAY
• A/B (in any order)
• A/E (in any order)
• QUALIFICATION

About IELTS Online Listening test

IELTS Listening online practice test – 33 belongs to the ‘Moderate’  category. So, if you are scoring 32+/40 in this practice test you are highly likely to hit  band 7 and above  in the real exam setting.

ALSO, DON’T FORGET TO TRY OUR IELTS ACADEMIC LISTENING PRACTICE TEST .

All the best !!!

• IELTS Listening Computer-Based Academic Practice Test – 31
• IELTS General Listening Practice Test – 34

Rajit is the co-founder and an active blogger at 'CIC Talks'. He is best known for his rich expertise in IELTS & Canadian Immigration. Feel free to connect with him on Instagram & Twitter .

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CANVASES, CARATS AND CURIOSITIES

The secrets of art presentation: from preservation to restoration.

Oct 3, 2023 | Rau Staff

The Secrets of Art Conservation and Restoration

Dive deep into the realms of art conservation, restoration and presentation. Discover the techniques, history and importance of keeping art vibrant for generations.

The Importance of Art Preservation in Safeguarding Cultural Heritage

Who are the experts?

• Surface cleaning
• Varnish removal
• Repair of tears and holes
• Repair of wooden supports
• Varnishing or revarnishing

Restoration techniques certainly vary across different mediums, as well as the extent of the damage. Common repairs for sculptures, for example, include routine cleaning, filling cracks, treating corrosion and patination.

Difference between Conservation and Restoration:

Additionally, restoration can raise the value of a piece. Rather than fretting about how much of the piece is original, buyers can confidently bring a restored piece into their collection knowing it will not need additional restoration for (ideally) quite a while. Through restoration, experts can ascertain what the original painting looked like and take the proper steps to show the piece’s true appearance.

Art Presentation: Showcasing Fine Art in the Modern World

The Intricacies of Art Restoration: 21st Century and Beyond

Preservationists: The Unsung Heroes of the Art World

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Restoration of paintings

The restoration of paintings on canvas and wood.

The restoration of the paintings constitutes the set of operations aimed at prolonging the life of the artefact and implies an intervention on the material. By extension with “restoration” we mean the result of the intervention and also the part subjected to restoration. According to the Charter of the Conservation and Restoration of Art and Culture Objects (1987), the term identifies “any intervention which, in compliance with the principles of conservation and on the basis of previous cognitive investigations of any kind, is aimed at returning, as far as possible, the legibility and, where necessary, the use of an object”.

In the restoration of paintings it is customary to refer with the following expressions – also discussed and contested in various fields – to two main phases of intervention: aesthetic restoration (intervention on the image) and conservative restoration (intervention on the structural material).

With “aesthetic restoration” we refer generically to operations not directly aimed at consolidating the material part of the work, as in conservative restoration, but aimed at restoring legibility to the work, such as the operations of cleaning and of pictorial reintegration . These actions are characterized by the need to combine technical-scientific methodologies with reflections and therefore choices depending on critical-aesthetic factors, according to a way of proceeding particularly characteristic of the Italian school of restoration.

The “conservative restoration” is instead the restoration intervention that is limited to consolidating the existing, excluding reconstruction or reintegration operations (as in the case of aesthetic restoration). In the restoration of paintings, for example, the operations identified with the expression are essentially aimed at consolidating the support , the preparation and the color , or interventions aimed at improving the mechanical characteristics of the product and at blocking, as much as possible, the chemical-physical and biological degradation processes in progress.

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Fake, copy, imitation, forgery and tampering

History of artistic diagnostics

Preparatory drawing

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Graffito in gilding – Video

Shell gold technique – Video

Oil gilding – Video

Water gilding – Video

Color alterations

Priming – Video

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The darkroom – Video

Squaring – Video

Raphael – Oil painting in Italy

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Consolidation and color fixing

Interventions on wood supports

Removal of overpaint

Pictorial restoration

Overpainting and skinning

Flaking and color loss

Support deformations

Damage to canvas supports

Biological damage

Simone Martini – Egg Tempera

Caravaggio – The Seventeenth Century technique in Italy

Tiziano – Oil painting on canvas

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Botticelli – The tempera grassa

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Infrared color photo

Fakes in art

X-ray radiography

Transmitted light

Macrophotography

Infrared photography

Infrared reflectography in paintings analysis

Raking Light

Ultraviolet fluorescence

Diagnostics – Introduction

Pictorial inpainting methods

Relining methods

Invasive analysis

Ground preparations – Introduction- Video

The importance of examining the pictorial material and the creative path in evaluating a work of art.

The contributions that treatises offer to the study of artistic techniques must always be compared and integrated with the data obtained through a careful visual analysis aimed at evaluating the changes that the materials may have undergone over time both due to natural alterations and the action of man: many incorrect evaluations are due to a poor consideration of this aspect [1] .

There are not a few historiographical theses that are based, paradoxically, on wrong restorations. This is the judgment attributed by critics and art historians to heavily repainted works that were therefore no longer able to express their original meaning [2] . As Stefano Turchetti keenly points out “the restorer must be at least a bit of an art historian, just as the art historian must be a bit of a restorer in the sense that he should at least be able to “see” a restoration, to know how to read it, in short have an eye trained to do this without of course having to act on the work. It has happened that art historians made attributions basing their theses on the restored or repainted parts of a painting. “In the past” there was a tendency to intervene on a painting to make it enjoyable “without taking into account that the painting must be respected and not transformed”. We therefore understand the importance of documentary research on past restorations as it emerged from the archives and from the reports on the restorations carried out in recent times.

The use of hot lixivia

Much of the damage that can be found on the paintings today is in fact the consequence of ancient cleaning operations. Between the Sixteenth and Eighteenth Centuries no distinction was made as to the type of dirt to be removed and each recipe could be used indifferently both on frescoes and on panel paintings.

Since the first written prescriptions, dating back to the Sixteenth Century [3] , the use of hot lixivia was often recommended, produced from oak “hard ash” combined with quicklime [4] . Adding other substances (such as soap, eggs, salt or honey) this mixture was applied to the paintings with a sponge and removed with another sponge soaked in water as soon as the work appeared to be clean. Together with the dirt and the paint, the substances actually attacked the binder, breaking it up in depth and continuing to act for a long time even after the apparent washing. Thus the pictorial layer, devoid of the element of cohesion, pulverized and detached itself.

Soda, potash, ointments, urine and wine spirit

In addition to the use of reactive solvents (such as caustic soda and caustic potash) or other basic and acid corrosive substances, the techniques and materials adopted to obtain rapid results were extremely varied. We know of the practice of spreading hot strong carpenter’s glue on the painting, which after drying was then stripped off with all the dirt [5] , or the use of “ointments” with imaginative compositions (it is not uncommon to find urine there) [6] or, again, of various abrasive substances. We also know of the practice of wetting the painted surface with wine spirit and then setting it on fire in order to soften the layers to be removed. [7] . The mechanical action of sponges and brushes rubbed on the surface during the application and removal of the various concoctions played a decisive role and, probably, caused the greatest damage [8] . The surface of the paintings that were treated in this way in ancient times has more or less deep abrasions, particularly at the crossing points of the craquelure lines, which give the whole work a pitted appearance (skinned surface) and are characterized by visible phenomena of skinning.

Lard rind or onion

Among these incorrect cleaning methods we also remember the widespread and harmful practice aimed at making the painted surfaces shiny: before important religious holidays it was, for example, customary to rub the paintings with the rind of the lard or even to clean them with onion [9] and wet them with boiled linseed oil, treatments that, while offering immediately captivating results, over time led to the formation of thick dark crusts. Furthermore, once the cleaning operations were completed, there was rarely any remorse in repaintings that would revive the colors and update the work to the taste or iconography of the moment; indeed, often the “restoration” intervention was identified with the repainting of the dirty parts [10] . The respect for the work of art felt as a historical and cultural testimony was actually still far from affirming itself: to this we can attribute, as Secco Suardo denounced in the Nineteenth Century, the endless number of paintings “barbarously not only peeled but flayed” [11] , then serenely repainted [12] .

In addition to the concealment of the wear caused by persistent cleaning, we can distinguish other causes that may have led to a repainting.

Often there was a need to intervene on a natural aging phenomenon or on an accidental alteration judged unsightly (such as tears, lacerations, cracks, etc.).

In other cases, partial or total modification of the composition was used for aesthetic, historical, political, religious or commercial purposes, with the aim of meeting the client’s taste changes or market needs.

In this way, works largely tampered with have come to our days which, rather than documenting the figurative culture of the century in which they were made, testify to the taste with which the ancient work was reinterpreted in the particular period in which they were ‘restored’.

Repainting and glazing

The ability to recognize non-original parts is generally referred to more or less vast gaps and extensive repainting but in modern restoration (only apparently less invasive) the attention must be shifted to cases in which light, reversible and apparently harmless glazes are applied which can equally distort the expression of a face or the chromatic transition between two backgrounds.

This type of retouching is the most subtle since it is often indistinguishable to the naked eye and to normal photographic reliefs.

Dismemberments, downsizing, transport

In addition to these alterations to the original appearance of the pictorial surface, other types of tampering carried out in the past must also be taken into consideration that may have led to a misleading reading of the work: dismemberment of polyptychs with replacement of frames, reduction of the size of the work (most of the time to adapt them to new environments or to obtain uniformity of measurements in a collection), replacement of the support (numerous paintings on wood were, in the past, “transported” to canvas), alterations of the original color by applying paints of yellow-brown hue on the pictorial surface.

Masters of art and science

As for the natural alterations not due to human intervention, i.e. the transformations that the materials of the work undergo with the passage of time, we must keep in mind that the degree of alterability of a painting is often correlated to the degree of knowledge that the painter had of artistic techniques.

It is therefore meant that ancient art is based, taking up the words of Matteini and Moles, “on a complex of technological acquisitions whose relevance, today, we are hardly led to recognize. The great masters of pictorial art, in the Middle Ages and in the Renaissance, were largely also masters of science according to the meaning – commensurate with the knowledge of the time – that is attributed to this word today. Therefore, not only geniuses like Leonardo, the master of masters, systematically applied it in the art of painting, but also the majority of the great painters who today are recognized as leaders of a movement hardly neglected to rigorously implement the acquisitions then known to create a product not only valid under the aspect of expression but also technologically built in order to successfully overcome the degradation of time” [13] .

The primary function of the finishing paint layer, to give an example of the above, is to protect the paint from external agents but also to modify the optical characteristics of the painted surface, influencing its final appearance. Any alteration of the paint layer will therefore reflect both on the aesthetics and on the state of conservation of the work and therefore also on the possibility of an incorrect interpretative judgment.

Ageing of the varnish

With the aging of the material there is a loss of flexibility and transparency: the paint film becomes dark, hard and brittle and, consequently, unable to resist the penetration of particles and external agents.

The colors, in general, lose depth and contrast and the painting appears of a yellowish-brown hue. The tiny cracks in the paint film, the gradual yellowing and the loss of transparency are due to both oxidative and photochemical processes but also to mechanical stress.

A less serious alteration that does not involve, as in the previous case, the need for partial removal and replacement of the paint is the so-called bloom effect, which can often be simply treated by smoothing the surface with a chamois hide. The term, from English, defines the whitening effect that can develop, in conditions of relatively high humidity, on a painted surface. The phenomenon initially takes the appearance of a bluish halo due to the dispersion of the light beam on the tiny drops of water trapped in the layer by condensation. Among the paints, those based on mastic resin easily give rise to the bloom phenomena, while there is a lower predisposition with the use of dammar .

The death of colors

As for the premature ageing of the painted surface, this can be caused by the choice of an unstable binder. In this regard, the passage in which De Mayerne describes the loss of color caused by the excessive darkening of the binder oil, which generates the formation of a brownish plasticized patina, [14] and therefore the consequent alteration of the original color: “the death of the colors occurs when the oil floating on the surface dries up and forms a skin that blackens in contact with the air” [15] .

As Alessandro Conti has acutely pointed out in many of his pages [16] he natural aging of a well-packaged oil instead generates a warm yellow or brown tonal unit which, by lowering the light colors and lightening the dark backgrounds, can soften the original chromatic crudeness of a work.

“Over time, the color timbre and the overall effect of a painting is bound to change” [17] and a testimony that does not allow doubts on the actual trust that the artists placed in time is provided by André Felibien des Avaux:

“I will tell you that it is for the same reason of this great union of the coloring that the excellent oil paintings, and executed a long time ago, present themselves with more strength and beauty because all the colors with which they were painted have had more ease to unite, merge, mix with each other as the most watery and humid was present in the oil dried” [18] .

The presence of a uniform layer of paint in good condition slows down the degradation processes to which the pigments present in the paint layer are normally subjected to. Each individual pigment particle is then wrapped in the binder, whose nature and state of conservation will also participate in slowing down the action of light, air and pollutants. These, in conjunction with humidity, tend to change the properties and composition of each individual pigment. Color alterations are in fact caused by chemical or photochemical phenomena. Some pigments, especially those that contain organic substances such as garanza lake or Indian yellow, are unstable under light; under the effect of violet and ultraviolet rays they therefore tend to turn pale. Other pigments of inorganic origin, such as verdigris, on the other hand, tend to become dark.

Contact with air and pollution can lead to other types of pigment alteration. We can, for example, mention the blackening of lead white or minium which, when combined with oxygen, are subject to oxidation reactions. The phenomenon is especially noticeable on wall paintings, where the protection of the binder is lacking and where humidity enhances the action of pollutants since, in addition to bringing them into solution, it acts as a means through which they come into contact with the work.

A final cause of the chromatic alteration of the pigments is linked to the chemical reaction (especially oxidation) triggered by other materials to which they have been associated (another pigment, the binder, the filler present in the preparation, a product added in the restoration, etc.). Natural ultramarine blue, for example, tends to turn gray in contact with lead white.

Some pigments, then, are attacked by the lime and therefore cannot be used in the fresco technique. Others, on the other hand, change rapidly in oil techniques: smalt blue, for example, was carefully avoided in oil paint because it decomposes releasing soluble cobalt which causes intense oxidation of the oils.

Finally, there is a last case of chromatic alteration to which many oil paintings are subjected which, if not correctly interpreted, can lead to stylistic evaluation errors and is given by the use of primers and colored preparations.

From the second half of the Sixteenth Century, the preparation on which the color was applied began to be mixed with earths and other opaque pigments. While preventing the maximum luminosity obtainable through the transparency effects of the colors on the white background, these preparations offered considerable advantages and, first of all, provided a medium tone as a base that allowed the artist to work simultaneously in both light and dark tones: immediately, with a few brushstrokes, the image was rendered in three dimensions with particularly marked chiaroscuro effects, conforming to the taste of the time.

However, it was necessary to paint with full-body strokes of color also to avoid the inconvenience of the progressive disappearance of the mid-tones because of the transparent background color due to the inevitable increase in transparency over time of the layers of oil paint.

The accentuated chiaroscuro effects that many works today show is therefore not due to the artist’s will but to the gradual disappearance of the half tones that the underlying dark preparation has “eaten”.

Manfredi Faldi ,  La documentazione materiale come supporto e verifica dell’analisi storico-stilistica nelle opere pittoriche , Florence 2003

[1] Cfr. M. Matteini, A. Moles, Il Laboratorio scientifico nella ricerca e nella prassi operativa del restauro dei dipinti, in Problemi di restauro . Riflessioni e ricerche , Firenze, EDIFIR 1992, p. 213

[2] Cfr. Veronica Briganti (a cura di), Intervista a S. Turchetti , BTA – Bollettino telematico dell’Arte, n. 9, 14 novembre 1994

[3] Si veda il Manoscritto Palatino 1001 della Biblioteca Nazionale di Firenze descritto in I Codici Palatini della Biblioteca Nazionale Centrale di Firenze, Roma, 1890-1940, II, pp. 476-7: “A far nette le figure in muro e in tavola che pareranno nuove. Recipe ceneri di rovere et tanta calcina et messedate ogni cosa insieme, poi fattene lissia caldata, poi pigliate del miel, sapon negro, et rosso di ovo, tanto di uno come dell’altro et fatte che ogni cosa sia insieme incorporata poi con questa lissia distemperata et con questa fregate ch’è cosa provata”. Questo ricettario si trova parzialmente riprodotto nello studio di A. Conti, Storia del restauro e della conservazione delle opere d’arte, Milano, Electa 1973, pp. 92-94

[4] Si veda Max Doerner, The Materials of the Artists and their uses in painting, New York, Harcourt, Brace and Company, 1949, p. 401, dove si parla anche dei bagni di olio di lino bollito e degli olii grassi della cucina che venivano usati per fare aderire i colori che erano stati indeboliti dall’uso della lisciva.

[5] A. Conti, cit., 1973, p.103

[6] Cfr. T. T. De Mayerne (1646), a cura di S. Rinaldi, cit., 1995, p. 163 e 250 (corrispondenti al f.56v e 145v del Ms. Sloane 2052).

[7] Cfr. quanto riportato da G. Secco Suardo ma si cita, qui e altrove, dalla ristampa anastatica Hoepli, Milano 1979, pp. 369-70: “il celebre prof. Giuseppe Guizzardi bolognese (…) poneva il suo quadro orizzontale, e con della creta vi formava tutt’attorno una specie di argine alto un dito, e costrutto in modo che non potesse scolarne un liquido. Vi versava allora dell’ottimo alcool, poi vi dava fuoco: e con un panno bagnato disteso fra le mani stava osservando l’effetto di quella fiamma: e quando, a suo avviso, era giunto il momento opportuno d’un subito vi stendeva sopra quel panno spegnendo immediatamente il fuoco.”

[8] Si confronti in particolare quanto descritto da Ulisse Forni, cit., 1866, p.127 e S. Suardo, 1866, ed. cons. Hoepli 1979, pp.364-5

[9] Si veda a proposito G. Secco Suardo,1866, ed. cons. 1979, p. 323

[10] Cfr. A. Conti, cit., 1973, p. 36

[11] G. Secco Suardo, cit., 1866, ed. cons. 1979, p. 42

[12] Si veda anche l’intervento di Silvia Bordini, Vernici e restauri nel Settecento: la Lettera sopra l’uso della vernice sulle pitture di Filippo Hackert, in “ Problemi del restauro in Italia” , Atti del Convegno Nazionale, Roma, 1986, pp. 163-274.

[13] Cfr. M. Matteini, A. Moles, Tecniche della pittura antica: le preparazioni del supporto , in “Kermes”, II, n; 4, Firenze, Nardini 1989, p. 49

[14] Cfr. P. Carofano, Sulle ricette di pittura del trattato di Theodor Turquet De Mayerne , in “La Diana”, anno I, 1995, p. 164-5

[15] T. T. De Mayerne (1646),  a cura di S. Rinaldi, cit., 1995, c.9v.

[16] Sul restauro, a cura di A. Conti, Torino, Einaudi 1988, si veda anche, dello stesso autore, Manuale di restauro, a cura di Maria Romiti Conti, Torino, Einaudi 1996

[17] C. Giannini, R. Roani, cit., 2000, p. 191 dove si legge anche che “l’espressione ‘tempo pittore’ è nata all’epoca del collezionismo barocco e non coincide con il gusto per la patina ma ne rappresenta un aspetto”.

[18] A. Felibien Des Avaux, Entretiens sur les vies et les ouvrages des plus excellens Peintres, anciens et modernes , vol. II, Paris, 1688, p. 240.

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Under the paints and pigments, the science behind art restoration

• Elisabeth Perez-Luna

Detail from Pietro da Cortona's 17th century painting "The Triumph of David" at Villanova University (Lindsay Lazarski/WHYY)

How does science play a role in restoring an elaborate 17th Century painting? 

To restore a painting, it takes a village, a team of art historians, conservation experts and cultural sleuths. Right now a 17th century painting, long abandoned at a dusty Villanova University library, is being brought back to its past glory.

For almost 60 years, the Faley Library at Villanova University held a hidden treasure in plain view — an enormous painting hanging high on the wall. But it was so dark and deteriorated that few noticed it. That all changed when a group of Villanova scientists and art historians decided to do something about it.

Separated from the rest of the library by a 10-foot-high chain-link fence with pad-locked doors, is the restoration site of the 17th century canvas. The painting, “Triumph of David” by Pietro da Cortona, was donated to the university in 1950. 

Going beneath the surface

The first step in approaching the painting was to bring a team from the prestigious University of Delaware Art Conservation Department to take a look at it. Lead conservator Kristin deGhetaldi remembers that, when she first saw the canvas, it was so damaged she wasn’t so sure about the condition.

So she climbed a scaffold, took a closer look, and took some miniscule samples and handed them over to Dr. Anthony Lagalante, science and chemistry professor at Villanova and the principal scientist in the restoration project.

He applied advanced analytical techniques to study and identify individual pigment particles. So, Lagalante says, “if Kristin wanted to know exactly what this blue is, we were able to establish how the artist worked, and dug through layers of paints and pigments, about 15 in this case, and figured out what was behind the surface of what we see to the naked eye, to establish the combined reflection and absorption of light.”

The tests revealed the chemical composition of the paint, an important factor in deciding what cleaning solvents to use. Importantly they also revealed that, under the varnishes and repainting of overeager, amateur restorers lay a true treasure.

“Lo and behold,” says deGhetaldi, “there were these brilliant, beautiful colors underneath,” sparking the idea of conserving the painting.  

Faced with this rare opportunity to have total access to an old canvas of this importance, chemistry professor Lagalante decided to use the painting as a living lab, a hands-on classroom, so to speak, to explore the many intersections of art, science and new technology.

Early radiology and spectography was pretty primitive, says Lagalante, but now they’re able to use advanced military techniques and technologies on paintings. It allows the team to look inside the painting in a non-destructive way and to find how Pietro da Cortona and his apprentices worked in his workshop near Rome.

He was a sought-after painter who worked on huge canvases and frescoes commissioned by wealthy families and the Catholic Church. Da Cortona’s “Triumph of David,” painted around 1620, depicts a joyful Biblical scene of the shepherd David delivering the head of Goliath to King Saul.

The parade has almost a cinematic quality. Villanova art historian Timothy McCall, who is part of the restoration team says, “You get the sense of dynamism and movement. You can almost hear this painting.”

From Rome to Villanova

So how did this Baroque canvas end up in a Villanova University library? The story reads like a novel; there’s love, death, greed, and the ravages of World War II.

It starts in the late 1920s when Alabama-born heiress Jenny Berry married a young Italian prince she met in Washington, D.C., diplomatic circles.

Berry, now Princess Eugenia Ruspoli, says McCall, “was about 40 years old. He was in his early 20s, had a name but not a lot of money. With her money they bought a castle where this painting had been.”

Then the castle was bombarded during the Second World War’s Battle of Rome in 1944. 

“U.S. troops were involved in the battle of Rome at Castle Nemi,” adds Anthony Lagalante. “It’s assumed that some of the damage to this painting was done during World War II, but we have no way of knowing.”

No one knows for sure how the artwork made it out of the castle and ended up in the United States, but what’s documented is that the princess met Villanova University’s Father Faley as he was raising funds for a new library and persuaded her it would be a good place for Pietro da Cortona’s “Triumph of David.”

An open forum

The entire restoration process will take approximately two years and, by now, almost half of the bottom part of the big canvas has been cleaned. The work is painstakingly slow, as scientists analyze each segment and seek the best techniques to unlock the secrets the canvas holds.

To do that, science professor Lagalante is also applying a technique called molecular imaging, which he says is a method of deeper analysis based not on the color or the absorption of light, but on how much a molecule weighs. 

Since it’s a university library and not a museum, students and the public can watch, get near or behind the canvas and talk to the conservators. There’s not a lot of action, but there is excitement in the air, especially when a new detail, like a face, emerges — or when a bunch of unattached feet suddenly appear.

There’s a reason and a name for that surprise, says Kristin deGhetaldi. “We begin to see things that the artist never truly intended us to see. They wanted to cover up this area here, because they decided to change it. When we first started, we saw evidence of eight different feet in this group down here, it’s called ‘pentimenti.’ When you have a painting of this size with multiple hands at work, there are going to be a lot of changes, and this is something that is commonly associated with his large painting. We know this for a fact.”

The team knows it can never bring da Cortona’s “Triumph of David” completely back to its original glory, confesses deGhetaldi. Still, this collaborative effort will leave behind an enormous sense of achievement and new scientific knowledge in the art of restoration.

For details on the restoration process and scientific research, visit the project’s website . 

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• How artwork restoration & conservation works [Guide]

The restoration of works of art (also called cultural heritage restoration) is a conservation process with the precise aim of maintaining the properties of a painting, a wooden structure, a fresco, or other types of works without altering their appearance or functionality.

In this comprehensive guide, you will learn everything there is to know about the restoration of works of art, including the principles, techniques, materials, and potential career paths.

The basics of art restoration

The restoration of works of art is a complex and delicate activity, requiring specific skills and respect for the historical and artistic value of the objects.

The purpose of restoration is to recover the original meaning of the work, ensuring its preservation and transmission to future generations.

Definition and history of restoration

Restoration refers to the activities related to the maintenance, recovery, restoration, and conservation of works of art, cultural heritage, monuments, and historical artifacts in general, recognized for their particular value.

Restoration is distinguished from conservation , which consists of preventive actions aimed at slowing the degradation of works and protecting them from external agents.

Restoration, as a scientific and professional discipline, emerged in the late nineteenth century, coinciding with the development of natural sciences and technology applied to the conservation and restoration of works.

Before that time, interventions on works of art were often arbitrary and harmful, based on aesthetic or ideological criteria, and did not take into account the history and materiality of the work.

Among the early theorists of restoration, we recall Gustavo Giovannoni , Alois Riegl , Cesare Brandi , Paul Philippot , and Umberto Baldini , who formulated the ethical and methodological principles that still guide the practice of restoration today.

Among the fundamental documents of restoration are the 1932 Restoration Charter , the 1972 Italian Restoration Charter , the 1964 Venice Charter , the 2000 Cracow Charter , and the 2004 Code of Cultural Heritage and Landscape .

Methodology and criteria of restoration

Restoration is a complex and articulated process that involves 3 phases:

• Preliminary phase
• Operative phase
• Conclusive phase

The preliminary phases include the historical-artistic study of the work, the analysis of its conservation status, the diagnosis of degradation, and the planning of the intervention.

The operative phases include cleaning, consolidation, integration, and surface finishing of the work. The conclusive phases include documentation, evaluation, and communication of the intervention. Restoration is based on some fundamental principles , ensuring its quality and correctness.

These include:

• Respect for the work : Restoration must safeguard the identity and authenticity of the work, without altering its historical and artistic meaning, nor adding or removing elements that are not strictly necessary.

work, in case of new discoveries or needs.

• Minimizing the invasiveness of the intervention : Restoration must be limited to the minimum necessary to recover the readability of the work, without exceeding or subtracting, and using techniques and materials compatible with the original work.

Regardless of the type of material to be treated, every restoration work must apply these general principles to reflect a complete project.

Techniques and materials of restoration

Restoration employs various techniques and materials, depending on the type and level of degradation of the work, and its nature and composition. Among the most common techniques are:

• Cleaning : Involves removing surface materials that alter the correct reading of the work, such as dust, dirt, varnishes, encrustations, etc. Cleaning can be mechanical, chemical, or physical, depending on the type of substance to be removed and the type of support to be treated.
• Consolidation : Involves strengthening the structure and cohesion of the work when it exhibits fragility, cracks, detachments, etc. Consolidation can be surface or deep, depending on the level of penetration of the consolidant, which can be organic or inorganic depending on its chemical nature.
• Integration : Involves filling gaps or losses of material that compromise the continuity and shape of the work. Integration can be material or chromatic, i.e., restoring the substance or color of the work, respectively. Integration can also be mimetic, neutral, or differentiated depending on the degree of similarity or distinction from the original work.
• Protection : Involves applying a filmogenic material, natural or synthetic, to enhance colors and protect the color from atmospheric particulate deposition and/or scratches/friction.

In the next section, we will see how some of these techniques can be applied to three different types of works and analyze new techniques related to their specific materials.

3 examples of art restoration

Restoration involves various types of works, including carved wooden artifacts, paintings, and frescoes, each presenting specific challenges and solutions.

1. Restoration of carved wooden artifacts

Carved wooden artifacts are works made of wood, such as frames, ceilings, furniture, sculptures, etc. Among the most common operations in this type of restoration are:

• Pest control: Involves eliminating wood-boring insects that attack the wood, causing holes, galleries, dust, etc. Pest control can be done using chemical methods, such as insecticides, or physical methods, such as heat treatment, anoxic treatment, microwave treatment, etc., depending on the type of wood and the level of infestation.
• Consolidation: Involves reinforcing the structure and cohesion of the wood when it exhibits fragility, cracks, detachments, etc. Consolidation can be done with gluing, inlays, nailing, stapling, etc., depending on the type of wood and the type of damage.
• Cleaning: Involves removing foreign substances deposited on the wood’s surface, such as dust, dirt, paint, wax, etc. Cleaning can be mechanical, chemical, or physical, depending on the type of substance to be removed and the type of wood to be treated. The purpose of cleaning is to recover the readability and brightness of the wood without altering its chromatic and material qualities.

One of the unique topics offered by CER is the restoration of carved wooden artifacts , with a three-year course covering all the mentioned techniques and more.

2. Restoration of paintings

Paintings are works created on different supports, such as canvas, wood, copper, paper, etc., with pigments of various kinds, such as oil, tempera, acrylic, etc.

The restoration of paintings aims to recover the readability and chromatic harmony of the work while preserving its materiality and authenticity.

Among the most common operations in the restoration of paintings are:

• Lining: Involves applying a new canvas to the back of the painting to reinforce the original support when it exhibits tears, deformations, detachments, etc. Lining can be done using various methods, with natural and synthetic materials, depending on the characteristics of the painting and the level of degradation.
• Filling: Involves filling gaps or abrasions in the paint film with materials suitable for the nature and color of the work, using natural and synthetic materials. Filling restores the continuity and flatness of the paint surface, preparing it for subsequent chromatic integration.
• Chromatic integration: Involves chromatically reconstructing the filled areas with compatible and reversible colors, using natural or synthetic binders. Chromatic integration aims to restore the unity and harmony of the work. Different criteria can be adopted: mimetism, chromatic selection, ‘rigatino,’ depending on the type of work and the client’s indications.

The Centro Europeo del Restauro (CER) offers a three-year course specialized in painting restoration , covering these specific techniques and other restoration topics.

3. Restoration of frescoes

Frescoes are works created on walls or ceilings, with pigments applied to a layer of fresh plaster, ensuring adhesion and resistance.

Among the most common operations in the restoration of frescoes are:

• Consolidation: Involves reinforcing the cohesion between the plaster and the wall, and between the various layers of plaster, when they exhibit cracks, flaking, detachments, etc. Consolidation can be done with injections of natural or synthetic materials, depending on the type of plaster and the level of degradation.
• Cleaning: Involves removing foreign substances deposited on the surface of the fresco, such as dust, dirt, salts, paint, etc. Cleaning can be mechanical, chemical, or physical, depending on the type of substance to be removed and the type of fresco to be treated. Cleaning aims to recover the readability and brightness of the work without altering its chromatic and material qualities.
• Integration: Involves filling gaps or losses of material that compromise the continuity and shape of the fresco. Integration can be material or chromatic, depending on whether it restores the substance or color of the work, and it can be mimetic, neutral, or differentiated, depending on the client’s indications.

In this case as well, CER offers a three-year course in fresco restoration that grants the state title of Cultural Heritage Restoration Technician.

Professional Outcomes in Restoration

Artwork restoration offers various job opportunities, both in the public and private sectors. There are two main professional figures operating in the field of restoration: the cultural heritage restoration technician and the cultural heritage restorer.

Cultural Heritage Restoration Technician

The Cultural Heritage Restoration Technician is the professional who collaborates with the restorer. They follow the operations indicated by the restorer, determining direct and indirect actions to limit the degradation processes of the assets and ensure their preservation.

The correct execution of these operations—under the direct supervision and control of the restorer—is a fundamental requirement .

To become a cultural heritage restoration technician, it is necessary to attend an accredited regional professional training course lasting three years.

Upon completion of the course, a certification of skills is obtained, allowing registration in the list of restoration technicians, which can be consulted on the Cultural Heritage Professionals portal .

The Cultural Heritage Restoration Technician can find employment in public or private entities dealing with the conservation and enhancement of cultural assets, such as museums, libraries, archives, superintendencies, foundations, associations, etc. They can also work independently, offering their services to public or private clients.

However, it’s important to note that the technician can work on protected works only if the work is entrusted to a Restorer, and the Technician is therefore their collaborator. Otherwise, they can only act on works not protected by the state, and if the client is public, the asset must not be protected, even when working independently with a VAT number.

Cultural Heritage Restorer

The Cultural Heritage Restorer is the professional who assesses the state of preservation and implements a strategy to limit the degradation processes of the constituent materials of the assets, ensuring their conservation and preserving their cultural value.

The restorer is responsible for analyzing, designing, directing, and executing restoration interventions, coordinating other operators performing complementary activities.

• Diploma issued by the Ministry of Culture’s high education and study schools
• Bachelor’s degree in Conservation and Restoration of Cultural Heritage
• Second-level diploma in a single-cycle enabling to the profession of cultural heritage restorer

Educational qualifications must refer to one of the 12 professional competence sectors provided by regulations . Possession of one of these titles allows registration in the list of cultural heritage restorers, available on the Cultural Heritage Professionals portal .

Which Restoration Path to Choose?

Artwork restoration is a fascinating and stimulating profession that requires passion, expertise, and responsibility. To embark on this career, it is necessary to choose the educational path that best suits one’s aspirations and abilities.

To choose which path to follow, it is important to assess one’s interests, aptitudes, and work expectations.

The Cultural Heritage Restoration Technician:

• Has a more operational and practical role
• Has a shorter and less expensive training
• Works on private or publicly unprotected works.

The Cultural Heritage Restorer:

• Has a leadership role of greater responsibility
• Signs the project and is responsible for its success
• Has longer training and requires managerial skills

Whichever path you choose, artwork restoration is a profession that requires dedication, preparation, and constant updating, but it also offers great satisfaction and opportunities.

The Centro Europeo del Restauro helps you in this journey from A to Z.

Check out the available courses and inquire directly on the page that interests you; you can consider us your personal advisors for artwork restoration—without obligation.

The conservation process

Find out about the tools, techniques and skills required to preserve A Royal Visit to the Fleet

Royal Museums Greenwich specialists have carried out vital conservation work on A Royal Visit to the Fleet by artist Willem van de Velde the Younger .

One stage of the treatment took place inside the Queen's House itself, giving visitors a unique opportunity to see paintings conservation in action.

What does it take to conserve a 300-year-old masterpiece?

Paintings conservator Sarah Maisey explains all.

What's currently happening with A Royal Visit to the Fleet?

During Conservation in Action we will be working on the retouching stage, which is one of the last and most visually important parts of the conservation process.

During our initial treatment of the painting, we discovered damage caused by earlier harsh restoration treatments.

In particular, if you get close to the painting you can see numerous small dark spots. These are especially visible in some of the lighter areas of sky, and are the result of the upper paint film having been abraded away, exposing the dark ‘priming’ layer underneath.

Up close, these dots are distracting to the viewer. From a distance they make some areas look darker than they should, disrupting the overall colour balance of the painting.

You can also see a few slightly larger areas of damage. These exist where the painting has lost areas of paint in the past due to tears in the canvas and flaking.

Retouching involves painstakingly applying tiny amounts of reversible paint in order to visually suppress this damage and abrasion, and allow visitors to fully appreciate the artist’s work.

Does 'retouching' mean painting over the original work?

No. Conservators working today are careful to only apply retouching paint to areas of the painting which are damaged or missing, which requires a high level of precision and dexterity – plus the use of very small brushes!

This is so viewers can see and appreciate as much as possible of the original artist’s work, without being distracted by the damage that exists in surrounding areas.

Restricting the application of retouching paint to just the areas of damage is time consuming (it would be much quicker to take a broad brush over a given area!), but it is important as it ensures that original, intact paint is not obscured. 

Restorers of past years were not always in a position to take such a careful approach.

Conservation only became a fully recognised profession around the mid-20th century with the introduction of specialist training programmes, a professional ethical framework and an increasing number of new materials and techniques.

Before this time ‘restoration’ was often carried out by artists or craftspeople who were simply tasked with cleaning up a painting in whatever way they found to be most effective and efficient.

This often meant that that their retouchings would extend far beyond the areas of damage (this is what we call ‘overpaint’) using mediums that would discolour over time and become difficult to remove.

Much of the work professional paintings conservators carry out today involves reversing this old restoration work and re-doing the retouchings in a more minimal way, using chemically stable, reversible paint.

Why did the painting need conservation in the first place?

Despite its importance, it has not been possible to display A Royal Visit to the Fleet in recent years due to issues with its structural instability and appearance.

The aesthetics of the painting were disrupted by several layers of thick, unevenly discoloured varnish and poorly matched overpaint from previous restoration treatments.

Most urgently, the paint film was exhibiting lifting and flaking, and there was a notable loss of adhesion between the original and lining support canvases. Both of these issues, if left untreated, would have led to further deterioration in future years.

What exactly are the paints that you use?

The paint medium being used here is a synthetic, resin-based varnish called Laropal A81.

It is chemically stable, so it won’t easily discolour over time. It is also chemically very different from the original paint layer, meaning it can be separated without risk of damage to the original. A layer of varnish is also added, which acts as a barrier between the original paint film and any retouching paint.

The medium is mixed with pigment to make the paint, and solvent is added to obtain the desired consistency.

Some colours come in the form of a premanufactured paint mix. For others the conservators make it themselves by grinding the dry pigment into the resin solution with a small spatula. These hand-made and factory-made paints are essentially the same thing, but the combined approach gives conservators a wider variety of pigments to choose from.

What other tools do you use for paintings conservation?

• During retouching the paint is applied with tiny, high-quality sable brushes . These are expensive, but they enable the paint to be applied in small quantities to very precise areas.
• The conservators also use optivisors (a headset with magnifying glasses on) to help them see the paint surface up close.
• Occasionally they will also use a mahl stick (a stick with padding on the end) which allows them to rest their hand without obscuring the surrounding areas of paint.  Black gloves are worn to prevent reflections on the painting's surface.
• Finally a palette is required to mix together the precise colour of paint required.

What has already happened during the conservation of A Royal Visit to the Fleet?

In order to fully understand what work needed to be done, the painting underwent a technical examination. Its condition was documented and photographs were taken.

Before any retouching work could begin, the painting’s surface was cleaned to remove the superficial dirt that had built up.

This was followed by an initial phase of consolidation to re-adhere the worst areas of lifted paint and make sure the paint layer was secure enough to withstand the work that would come later.

This involved inserting very small amounts of a warm, fish bladder glue called isinglass under the lifted edges of the paint, before gently heating the edges with a spatula to lay them back down.

We discovered at least two layers of varnish on the painting.

The first, being relatively recently applied, was only slightly discoloured and was easy to remove with a mild solvent mix applied via cotton wool swabs.

The lower layer was significantly older.

It was also contributing most to the painting’s streaky, yellowed appearance, so its removal made a dramatic difference to the work, bringing out the cool colours and increasing the sense of three dimensionality.

Once the varnish removal was complete, a second round of consolidation was carried out to ensure that the paint layer was as stable as possible ahead of the 'relining' phase.

Relining involved the removal of an old, degraded supporting canvas – scraping away the animal glue and flour adhesive which had been used to attach it – and re-attaching a new canvas with a stable synthetic adhesive.

Although it might sound simple, this stage involves applying heat and pressure, which carries a risk of damaging the painting, so this process needed to be very carefully managed.

Specialist expertise and equipment were required, and the painting had to be sent off-site for this part of the process.

Once back in the studio, an initial protective varnish layer was applied to the surface of the painting, which acts as an isolating layer ahead of the retouching process.

Have you learned anything new or surprising while you've been working on the painting?

Some interesting discoveries were made about the artist’s unusual choice of canvas support.

Because the painting had previously been lined (i.e. a support canvas had been applied to the back of the original one during a previous restoration treatment) the original artist’s canvas hadn’t been visible from the back.

When the lining canvas was removed, the original canvas was found to have a set of distinctive dark blue indigo lines running horizontally through the fabric.

This marked it out as 'ticking fabric': a high quality, robust type of canvas typically used for beds, but an unusual choice for an artist’s support.

The size used for the Royal Visit wouldn’t have been available in England at the time, so it’s likely it was imported from the Low Countries at quite some expense.

Nevertheless such a price tag would have befitted an important royal commission and would have meant that the painting could be executed on a single piece of canvas, avoiding a potentially visually distracting seam down the centre of the work.

Keep exploring

15 Behind-the-Scenes Secrets of Art Restorers

Nothing lasts forever, and that includes expensive and beloved works of art, which can be damaged through accident or over time through natural decay. Fortunately, the efforts of a skilled art conservator or restorer can extend the lives of such pieces and keep them looking beautiful for a very long time.

Art conservation refers to the process of maintaining works of art against future damage, while restoration more often refers to repairing damage that has already occurred. Many professionals are adept at both. For those on the outside, the work these experts perform can seem either romantic and rewarding, or painstaking and nerve-wracking. We talked to several experts in the field for their insight about what goes into keeping art beautiful. 

1. CONTEMPORARY ART CAN BE HARDER TO RESTORE THAN OLD MASTERS.

One might think that centuries-old paintings, with their layers of accumulated grime, would be harder to restore than works done much more recently. But Barbara Bertieri, a painting conservator and restorer in New York City who represents Fine Arts Conservation Inc along with Abraham Joel, says that’s not the case.

“With Old Masters,” she says, “the artists were trained in certain ways, and were very good at preparing pigments and canvas.” Because the older painting techniques are so well-established, they are quite familiar to restorers, as are the means of repairing such works. Contemporary art, though, can be much more unpredictable, and include all sorts of materials. “You never know what you’re facing,” Barbara says. “There can be water-soluble paint, oils and even objects in the same painting.” That can make the work a much bigger challenge.

2. THE ART MARKET DRIVES A LOT OF BUSINESS. 

Steve Tatti , a sculpture conservator in Manhattan, has seen his fair share of clients, from museums to private collectors to entire municipalities. Increasingly, he says, restoration is driven by private collectors looking to cash in on their investments, rather than larger institutions.

“A lot of the time, someone wants to sell something and it has not been maintained,” he says. In that case, the client will hire a restorer to make the necessary repairs so that the piece will bring the best price at auction. Other times, economic trends may open up a whole new market. Barbara and Abraham say they cater to a sector of the Indian art market that has only cropped up in the last 10 to 15 years, due to the growth of the Indian economy and a new interest in art there.

3. SO DOES NATURE. 

Often it’s the inevitable damage done by natural forces that brings work to a restorer’s door. Many of the pieces at Barbara and Abraham’s studio bear cracks, tenting, and discoloration that are the result of changes in humidity, temperature, light, and age. Steve, whose company specializes in outdoor sculpture, grapples even more directly with the effects of nature in the course of his work. Marble and stone melt away over time due to acidity and pollution in the air, while brownstone, he says, “explodes in layers.” Bronze holds up better, though oxidation does eventually take a toll.

4. SO, UNFORTUNATELY, DOES HUMAN ERROR. 

Mistakes happen, but they can be all the more dire when a piece of art worth thousands or millions of dollars is involved. High turnover in auction houses and warehouses can sometimes lead to accidents , and even works in museums can be subject to misfortune . Barbara describes a situation where a client’s piece fell from its frame to the floor and broke because it was framed incorrectly. Steve says he commonly encounters clients who take the idea of outdoor art a bit too literally and “will put a sculpture outside and think that it needs no maintenance,” leading to more serious damage later on. 

5. THEY HAVE TO VIEW THINGS IN THE RIGHT LIGHT. 

Restorations that look great in one type of lighting can be glaringly obvious in another. For this reason, Barbara and Abraham make sure to look at their work under as many different artificial and natural lighting conditions as possible (they also emphasize the need to look at a repair from as many angles as possible).

UV light is also a common tool in a restorer’s arsenal. Light within the ultraviolet range causes organic materials, and some inorganic ones, to auto-fluoresce (or glow, basically) at different levels of intensity, depending on their age and when they were applied, revealing even skillfully done touch-ups. This can help the restorer understand what kind of work has already been done on a piece. 

6. THEY BORROW FROM OTHER INDUSTRIES.

In addition to artistic implements such as brushes and paint, and high-tech devices like UV, infrared light, and x-ray, restorers also borrow items from unrelated fields. “This industry is not big enough that they are going to make everything we need specially for us,” Barbara says, “so we end up borrowing from a lot of other places.” This includes using scalpels, droppers, and clamps from the medical industry, picks from dentistry, tweezers from jewelers, and even polyester sailcloth for backing damaged paintings.

7. SOMETIMES THE BEST TOOL IS NO TOOL. 

A conservator’s accumulated knowledge and intuition can be their most useful tool. Steve says that his training in Florence in the 1970s focused on a holistic approach that relies primarily on his senses. “I rely on my eye, my touch, my taste, my sense,” he says, explaining that he can also knock on a metal sculpture and tell what type of metal it is made of, or touch a piece of stone and determine what it is based on its temperature. He allows that this ability is not necessarily so magical—it’s just a product of experience. “Even guys who work in scrap metal can do the same thing,” he says.

8. THEY KNOW WHEN TO LEAVE WELL ENOUGH ALONE. 

An important part of being a skilled conservator is knowing when it’s better not to interfere. “Very little should be done to paper,” Abraham says. He stresses that overzealous treating or bleaching a discoloration on the border of a work on paper risks ruining the whole thing, particularly if the central image itself looks okay. Likewise, applying a varnish with the intent of protecting a painting risks changing the color saturation or character of the work. And over-cleaning of a painting with a harsh solvent can lift away pigment that cannot be returned.

9. THEY CAN GET LONELY, AND SOMETIMES A BIT OBSESSIVE.

While the work of a dealer involves a lot of interaction with clients and schmoozing, the job of an art restorer can be a solitary one requiring long hours in close communion with artworks. “We don’t get to speak to a lot of people in a typical day,” Barbara explains. “It’s just you and your work.” And that work can be extremely exacting. Barbara explains that restorers can become “almost obsessed. If you are in a gallery and you see someone looking very closely at a painting,” she says, “that is probably a restorer.”

10. THEIR JOB CAN BE HAZARDOUS.

While the use of such materials is on the decline, art restoration has historically involved hazardous solvents and other substances. Barbara notes it was once common practice for restorers to clean their hands in acetone, turpentine, and mineral spirits, materials known to irritate or damage the skin, lungs, and mucous membranes.

Working environments, too, can be difficult. Steve’s company was tasked with removing two murals by the artist Carybé from a JFK Airport terminal while it was being prepped for demolition and lacking heat in the middle of winter. Plus, when deadlines are looming, or there’s some kind of emergency, art conservators will often work all night. 

11. THERE IS USUALLY NO SCRIPT TO FOLLOW.

For a restorer, jobs like the removal of the Carybé mural from the wall of JFK Airport can have no precedent. Each mural weighed one ton, was nearly 17 feet tall and over 50 feet long, and was deeply integrated into the wall structure. Steve describes being uncertain if the murals would disintegrate while being removed. “It was a once in a lifetime experience,” he says, but “beyond nerve wracking—more like an out-of-body experience. There was no way to prepare for it. No way to plan for it. Either you have to be up for these things, or ...”

12. SOMETIMES THEY UNCOVER FAKES.

The shadowy world of art fakes and forgeries provides fodder for news stories as well as books and movies, but these stories are considerably less fun for buyers and others on the receiving end. It sometimes falls to the conservator to break the bad news to a client. Abraham describes working on a collection of paintings being represented to a Far East collector as 15th-17th century works by Raphael, Rubens, Titian, and others, only to have x-rays reveal that they were actually 19th century copies. On the flip side, sometimes a conservator has the happy experience of proving a painting’s provenance. A highlight for Barbara and Abraham’s Fine Arts Conservation was revealing the signature on Antoine Dubost’s 1804 work Sword of Damocles during cleaning. 

13. SOMETIMES THEY CREATE FAKES.

Occasionally the best way to protect a valuable piece of public art from the elements is simply to bring it indoors. Many institutions and municipalities, particularly in Europe, have made the decision to place original works in more protective surroundings and to create a copy in hardier materials for outdoor display. Steve calls this practice “the greatest solution for outdoor conservation.” His team was responsible both for restoring the figure of Lady Baltimore on the 1814 Baltimore Battle Monument and for creating the replica figure that currently stands on the monument (the original was brought to Maryland’s Historical Society). They are carrying out similar work on the wooden figure of St. Paul that graced the top of St. Paul’s Chapel in Lower Manhattan, which will be fully restored, moved indoors, and replaced by a resin replica.

14. NO PUBLICITY IS OFTEN THE SAME AS GOOD PUBLICITY.

The work of a skilled restorer is often invisible, taking place deep behind the scenes, and is aimed at erasing damage done to art rather than drawing any attention to it. Abraham points out that silence is often a sign of a job well done. “If you do your work well, nobody knows about it,” he says.

15. THE BEST CLIENTS ARE THE ONES WHO LOVE ART. 

While many in the business say art collecting is becoming increasingly commodity-driven, there are still collectors who are motivated by a love of art itself. Collectors with a strong passion are Barbara’s favorite: She explains that those who view art as an investment can be more frustrated by damage to their property than glad to find a professional who knows how to fix it. They can also focus too much on the fact that the value will not be the same as before. Art lovers, on the other hand, “think of [restorers] as someone who rescues their treasure. They thank us so much, it’s good for us.”

All photos courtesy iStock.

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Wall paintings are the oldest known form of painting , dating back to the prehistoric paintings in the Altamira cave in Spain and the Lascaux Grotto in France. In the last decades of the 20th century, the conservation and restoration treatment of two Renaissance masterpieces of wall painting, Michelangelo’s frescoes in the Sistine Chapel in Vatican City and Leonardo da Vinci’s Last Supper (1495–98) in Milan, drew the world’s attention to the environmental and structural vulnerabilities of these treasures.

Commonly, large paintings placed into architectural niches are considered “mural paintings,” even those stretched over stationary or expandable wooden bars in the manner of easel paintings. Strictly speaking, however, “wall paintings” are distinguished from other murals by virtue of being executed directly onto primary wall supports, which are typically plaster, concrete, masonry, or stone. Wall paintings are integral to architecture, in both a material and aesthetic sense. The conservation of wall paintings inevitably concerns not only the paintings themselves but also the larger context of adjacent building materials, building maintenance, use, and preservation. Depending upon their construction and the degree of involvement of the wall support, wall paintings’ conservation and restoration needs may be closely allied to those typical of easel painting or to those of porous stone (see Paintings on canvas , above, and Stone sculpture , below).

From the point of view of conservation, different types of wall paintings have features in common, though the techniques of restoration required for each can differ greatly in detail. In buon (“true”) fresco, pigments mixed only in water are painted directly onto a freshly prepared layer of damp lime plaster. Pigments are permanently bound to the plaster as a result of a chemical change, as the fresh lime becomes calcium carbonate upon drying. In fresco secco (“dry”), the artist applies paints to already dried plaster. The stability of these paintings depends upon the presence of a binding medium—such as egg, oil, gum, or glue—mixed with the pigments to adhere them adequately to the wall surface. This type of painting is found in the wall paintings of ancient Egypt . In marouflage, a more modern variety of wall painting, paintings on canvas are mounted to the wall using an adhesive.

Chief among the hazards to all these types of wall paintings is excessive moisture . Damp may rise through the walls, originating at the level of ground contact and spreading upward. Prevention of rising damp is sometimes achieved by cutting into the wall beneath the mural and inserting a “damp course” of water-impermeable material or a high capillary tube that draws and deflects the harmful accumulation (see Architecture , above). These avenues of intervention are, however, often prohibitively expensive due to the complex engineering they require. If these approaches are not possible, amelioration of the problems may be achieved by reconfiguring drainage at the exterior of the building, and thereby reducing the overall quantity of available moisture. Damp may also come from the outside wall, where direct infiltration of rainwater may penetrate through the substrate to the face of the painting, evaporating at the paint surface. In this instance, localized building repairs or efforts to shield the exterior wall may attenuate the problem. Moisture may also result from condensation on a cold mural surface, a phenomenon common in churches, tombs, or buildings that are heated only intermittently or that are subject to excess ambient moisture generated by the respiration of crowds of visitors. More continuous and uniform heating of the wall may adjust this situation, provided that ambient air is not dried so rapidly that “efflorescence” (the formation of salts) occurs. Lastly, water damage caused by leaking roofs, clogged drainpipes, and faulty plumbing is easily stopped by repairing these systems. Conscientious maintenance is the best preventative treatment.

Damages to wall paintings due to moisture may include blanching, drip staining, and delamination of paint layers due to efflorescence. Crystallized salts may form above, below, or within the painted image, resulting in disintegration or obfuscation of the image and creating a salty “veil.” The conservator must avoid coating the painting with a water-impermeable material, such as wax or resinous products, so that the damp can penetrate freely without meeting a barrier at the inner surface; when evaporative sites are blocked, moisture will move laterally, expanding areas of damage. Problems such as mold growth and mildew are secondary results from overly damp environments .

Another enemy of wall paintings is more insidious and also more pervasive . Due to the worldwide use of fossil fuels and automobile emissions, concentrations of sulfur dioxide in the atmosphere have markedly increased. In the presence of moisture, pollutants forming sulfuric acid can quickly erode the calcium-carbonate component of most cement- and lime-based wall paintings. This “acid-rain” effect converts calcium carbonate to calcium sulfate . The volume of the sulfate crystal is almost twice that of the original carbonate of the mural, which causes internal pressure within the pores of wall fabric that can lead to fracturing. Further, the sulfate has a greater capacity to absorb moisture, thus perpetuating and exacerbating the cyclic wet-dry process of decay. Polluted environments can bring about the blackened, sooty surfaces associated with fossil-fuel particulates to a wall painting and can also discolour certain pigments traditionally found in Renaissance paintings, such as white or red lead, malachite, and azurite.

In the face of such damage from moisture and pollution, the conservator works to halt the causative agents of deterioration and then proceeds to stabilize insecurities such as spalling plaster or flaking paint. Many new conservation treatments were developed in the second half of the 20th century: chemical poultices, gel technology, and ion-exchange resins have allowed advances in cleaning methods, reduction of salt deposits, and consolidation techniques. Natural or synthetic adhesives and inorganic consolidants are now utilized, but they must be chosen for compatibility with the paint medium and used with discretion to avoid film-forming blockages. Hypodermic injection of adhesives followed by light pressure while drying has also become an effective way to mitigate many problems of detached paint or wall support.

Conservators often develop solutions in the face of a specific problem. For example, after the flood of the Arno River in Florence in 1966, Italian conservators developed drastic but necessary and highly expert methods to transfer frescoes from decayed walls. These range from the strappo technique to the stacco a massello . While in practice these methods are not always clearly distinguishable, strappo , the more radical procedure, consists of gluing canvas firmly to the surface of the fresco and then pulling and easing away a thin layer of the plaster containing the pigment particles of the fresco. The bond between the facing and the fresco must be stronger than the internal cohesion of the plaster. Excess plaster is removed from the back, revealing the thinned fresco in reverse. This thinned pictorial layer is then fixed to a rigid support after recoating the reverse with materials optically simulating the original underlying plaster. Unfortunately, much of the original surface character of the wall and density of the pigment layer is sometimes irreversibly altered by this technique, so the method is now seldom used. Less intrusive is the stacco method; a thicker layer of plaster is retained along with the fresco and is smoothed flat on its back surface before the composite rigid layer is mounted to a prepared support. Lastly, in the procedure called stacco a massello , the least intrusive to the fresco but more challenging transfer procedure due to mass and weight, the wall painting is removed with its entire original substrate. This feat requires bracing the wall with counter-forms to avoid damages due to torque, vibration, and other mechanical strains. Selecting the method of transfer depends greatly on the stability of the painting, the type of deterioration encountered, and the limitations of size, weight, and practicality.

Whenever possible, transfer techniques are abandoned in favour of conservation and restoration treatments carried out in situ, with the conservator working from the surface and preserving as much original building fabric, character of surface, and contextual meaning as possible. The art conservation community , including art historians and preservation specialists, generally hold that murals and wall paintings are physically and aesthetically dependent upon their architectural context. The so-called “site-specific” nature of the paintings is valued, and the character of the original site is maintained as nearly as possible; relocation may cause diminishment of meaning or appreciation. The disciplines of wall and mural painting conservation, engineering, and architectural conservation are symbiotic, and each specialty is increasingly called upon to contribute to a holistic preservation plan.

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Restoration of Minoan paintings: Imitation or reproduction?

Introduction.

The Minoan civilisation was an Aegean Bronze Age civilisation that arose and flourished on the island of Crete from around the 27th century BCE to the 15th century BCE. Rediscovered at the beginning of the 20th century through the work of British archaeologist Sir Arthur Evans, the Minoan art tells of a people who were keen observers of their world, in touch with the environment and enjoying the world they lived in.

The greatest collection of Minoan art is still on Crete in the museum at Heraklion, near Knossos. The world the art evokes is in some ways distant and strange and yet, at the same time, reassuringly recognisable and somehow modern.

However things are not what they seem: these famous icons are largely modern. Any keen observer at the museum can spot what survives of the original paintings amounts, in most cases, to no more than a few square inches. The rest of the painting is more or less a reconstruction, commissioned in the first half of the 20th century.

The difficulty lies in whether a reproduction can be counted as an example of the original. How much of the original needs to be present for the artefact to be considered a copy of the real thing?

The art of the fresco at Knossos

Archaeologists in the late 19th century had started to focus on early Ancient Greek sites. Heinrich Schliemann had discovered the tombs at Mycenae i­n 1876 and brought to life tales of King Agamemnon, his palace and gold. Many other archaeologists began to look for other sites twenty four years later Sir Arthur Evans began to excavate the site at Knossos on the island of Crete. This promised to yield a complex that would include a palace. He named the civilisation that had dwelt at Knossos the ‘Minoans’, after the mythical King Minos who is said to have held the throne there.

Numerous fragmentary wall paintings emerged from the excavations at Knossos. To make sense of these fragments Evans turned to Emile Gilliéron (1850-1924), who was later succeeded by his son Emile (1885–1939), as chief fresco restorers at Knossos where they worked for more than thirty years. They were recognised as the best archaeological illustrators working in Greece.

The frescoes at Knossos were especially exciting because they provided glimpses into the world of the Minoans. The first well-preserved image of the face of a Minoan to be discovered on one of the palace walls was that of the ’ Cupbearer ‘, which Gilliéron restored. It was clear this was part of a representation of a large procession decorating one of the main entrances to the palace. Evans decided to reconstruct the entrance and recreate the fresco, so the younger Gilliéron recreated more of the procession on a concrete superstructure reconstituted under Evans’ guidance.

Gilliéron also restored the ’ Prince of the Lilies ’ in 1905 from fragments such as a small piece of the head and crown, part of the torso and a piece of the thigh see Figure 1. Records from the original excavation suggest the fragments were found in the same area of the ancient palace, but no face was ever found, and some have commented that it is not certain that all the fragments came from the same painting. Because the painting is a reconstruction from a limited number of fragments the overall picture appears awkward and there is no firm evidence that the subject was royalty.

Figure 1: Prince of the Lilies fresco.

© The Art Archive / Alamy

There is similar hint of controversy about the ’ Ladies in blue ’. It was first recreated by Gilliéron after the discovery of a few fragments, but that restoration was itself badly damaged in an earthquake.

One of the most important frescoes is the ’ Priest King ’ excavated in 1901 in the North-South corridor. The older Gilliéron worked on six fragments and in 1907 the Metropolitan Museum of Art (Met), in New York, acquired copies of those fragments. Art historians at the Met pieced the fragments together to form a single relief. Later more fragments were found and Gilliéron made further restorations. A copy of this final restoration was placed where Evans thought the original would have been in the palace.

The well-known ’ Bull Leapers ’ fresco looks correct, but even here some have questioned the details of the border’s restoration. The original fragments of the top and bottom borders consist of overlapping variegated rock patterns between narrow bands with dentil patterns. However, there is no evidence supporting the rock pattern framing the sides, and it may be a modern addition.

Figure 2: The Bull Leapers fresco.

© Peter Horree / Alamy

Figure 3: Close detail of one of the bull leapers from the Bull Leapers Fresco.

© age fotostock Spain, S.L. / Alamy

So much excitement was aroused by the find at Knossos that the Gilliérons established a successful business selling reproductions of the antiquities from the Minoan and Mycenaean civilisations. These reproductions were sold around the world, inspiring other artists and writers like James Joyce (1882–1941) and Pablo Picasso (1881-1973).

The restorations remain controversial because the remains are fragmentary and the original composition cannot be determined with certainty. But the Gilliéron restorations remain a clever solution to the problem of what they originally looked like in that it combines the existing pieces into a single figure.

The Artists

Emile Gilliéron (1850–1924) was born in Villeneuve, Switzerland. He studied art and trained in Munich and Paris before moving to Greece in 1876. In Greece he worked as archaeological illustrator for Heinrich Schliemann and other researchers became an art teacher and employed as drawing master to young members of the Greek royal family. One of his pupils was Giorgio de Chirico (1888-1978) whose later paintings, such as Ariadne , drew on the mythology of Knossos.

The son trained at the Polytechnic in Athens and the École Nationale Supérieure des Beaux-Arts in Paris, before assisting his father at Knossos. He focused on the work of restoring the frescoes in the Heraklion Museum after the early excavations ended in 1913. He produced illustrations for Evans’ four-volume book, The Palace of Minos at Knossos , published between 1921 and 1936. The Greek Government appointed him ’ Artist of all the Museums in Greece’ , a position he held for 25 years, giving him access to many new archaeological finds.

Others artists were involved in the restoration, including Piet de Jong (1887–1967) who painted most of the ’ Dolphin’ fresco in the 1920s.

Restoration of Minoan paintings: imitation or reproduction?

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Documentation of paintings restoration through photogrammetry and change detection algorithms

• Dante Abate   ORCID: orcid.org/0000-0003-4469-5230 1  

Heritage Science volume  7 , Article number:  13 ( 2019 ) Cite this article

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The philosophical and theoretical foundations of the Theory of Restoration, envisioned by Cesare Brandi in 1975, are established around clear and straightforward guidelines on what is ethically acceptable, and unacceptable, in conservation. Specifically, the Italian scholar advocates for the complete reversibility of restoration work and respect for the history of an artwork. Indeed, according to these concepts, all interventions should be fully reversible so to return the object to its initial conditions without any damage. Bearing in mind these assumptions, a detailed documentation of all the steps of the conservation process, and the possibility to retrieve them a posteriori, must be considered essential. This concept especially applies when dealing with paintings restoration characterized by fine and small details. In recent years, the tendency is to favour minimal invasive interventions ranging from consolidation actions, cleaning samples, and colours retouching. Materials change more or less conspicuously over time according to their consistency and the intensity of the changing factors. Icons do not make an exception to this rule. This process affects the icon’s whole structure: the support, the painting itself and the varnish coating. This paper investigates the performance of change detection algorithms, developed in the remote sensing domain, and, in the framework of this research applied at a microscale (paintings). Each phase of the restoration process is documented exploiting a multi-epoch image acquisition. A monitoring methodology coupled with photogrammetry and 3D shape analysis is tested and described. It is anticipated that the proposed innovative use of change detection techniques can be applied to different kinds of painted surfaces. An icon, today preserved at the Byzantine Museum Makarios III Foundation in Nicosia and restored by the Department of Antiquities of Cyprus labs, has been used as a case study.

Introduction

For almost the last two decades digital technologies have been increasingly used to address art conservation problems and provide objective diagnostic and documentation tools.

Concerning the restoration of paintings, the scientific community has indeed proposed a variety of methodologies for the study, identification, and mapping of the decay. Techniques such as multispectral analysis [ 1 ], virtual restoration [ 2 ], Geographical Information System (GIS) [ 3 ], and 3D modelling [ 4 ] have proven to be successful when integrated in a multidisciplinary research environment.

The documentation process of painted artworks is today mainly realised through digital cameras using direct or oblique light, coupled, when possible, with colour checkerboards and metric rulers. The typical outcome is a single-shot image often influenced by more or less visible perspective distortions and usually light changes due to the reflectivity of the surfaces.

When needed, the collected images are a posteriori visually analysed to identify the changes the artworks went through during the restoration. The proposed study presents a novel way to exploit change detection procedures and photogrammetric techniques to monitor and retrieve variations occurred on the pictorial surface at different stages, automatically and straightforwardly.

Change Detection can be defined as the process of identifying transformations of a surface over time. In this study, it has been applied for the first time in heritage science to the restoration procedure of a painted item, a Byzantine icon.

Eleven image data sets have been acquired and processed to highlight the changes that occurred due to the conservation interventions.

In details, the paper is structured as follow: (i) description of the data collection procedure through photogrammetric techniques (see “ Photogrammetric surveys ” section); (ii) data post-processing for the production of radiometrically correct orthophotos (see “ Data post processing ” section); (iii) change detection algorithms application over different epoch datasets in 2D and 3D space (see “ 2D change detection analysis ” section); (iv) analysis and interpretation of the results (see “ 2D change detection data interpretation ” section).

Additionally, an assessment of the geometric conservation condition of the wooden support has been realised.

Methods/experimental

2d change detection.

Many techniques have been developed in the remote sensing domain, with the purpose of identifying the differences occurred on the Earth surface over time. This task, usually referred to as change detection, can be approached in a supervised or unsupervised way, being the latter preferred when no training samples or only a little knowledge on the ground is available.

The Multivariate Alteration Detection (MAD) algorithm was selected in this study after a comparison with the well-known and widely used in remote sensing, Principal Component Analysis (PCA) algorithm [ 5 ]. The latter is a statistical procedure used in several domains and developed to transform a set of correlated variables into a new set of uncorrelated variables considering the principal directions in which the data are spread in space. Whereas PCA allows reducing the size and redundancy in the original data, MAD considers maximum autocorrelation eliminating issues related to the possibility that a dominating element in the image affects the PCA components. In addition, MAD is invariant for linear transformations of the data, making it insensitive to the application to raw Digital Numbers (DNs) or transformed images [ 6 ].

The MAD is a broadly used mathematical analysis method of images linear transformation. Introduced by Nielsen et al. [ 7 ], MAD seeks to improve the simple image differentiating techniques by exploiting the Canonical Correlation Analysis (CCA). Indeed, the main principle is to make the images as similar (i.e., correlated) as possible, before computing their difference. The latter is carried out by using CCA to find two sets of linear combinations of the original variables, where the first two linear combinations (called canonical variates) are the ones featuring the most significant correlation (called first canonical correlation). This process is then iterated to compute the higher-order canonical correlations/variates, under the condition to be orthogonal (i.e., uncorrelated) to the previous ones. If N is the maximum number of bands in first and second input images, the differences between the corresponding pairs of variates (called MAD variates or components), constitute N change maps that are usually combined in a single multi-band image.

Since MAD analysis lacks in semantic interpretation, the adoption of a combined procedure can be preferred to support the understanding of changes found by MAD. For this reason, Nielsen proposed to apply the Maximum Autocorrelation Factor (MAF) transformation to the MAD components [ 8 ]. MAF transform seeks to isolate the noise component of the data, by computing a new set of variates out of the original ones, where low order components feature maximal spatial autocorrelation (signal), whereas the highest order variates feature minimal spatial autocorrelation (noise). Accordingly, the first MAF-MAD component will identify areas with maximum changes, while the noise is expected to be isolated in the lower order MAF-MAD components. The use of the MAD technique, either alone or in combination with MAF transform, is well-known in the remote sensing community [ 9 , 10 , 11 ].

2D change detection literature review

Detecting changes in images of the same scene acquired at different times has seen significant development in a wide range of disciplines such as video surveillance, remote sensing, medical diagnosis, driver assistance systems, civil engineering, disaster management, and cultural heritage [ 12 ]. However, up to date, there is no record it has ever been used for the documentation of the restoration process or monitoring of painted surfaces.

In the last three decades, the research community has proposed a variety of change detection methods using different approaches such as image differencing, image rationing, principal component analysis, change vector analysis and post-classification. A complete review of change detection algorithms can be found in [ 13 , 14 , 15 ].

Change detection algorithms are usually categorized into two main typologies:

Algebra-based change detection, including image differencing, image rationing, image regression, vegetation index differencing, change vector analysis and background subtraction techniques;

Classification based change detection such as post-classification comparison, spectral–temporal analysis, unsupervised change detection, and hybrid change detection.

Although the study reported in this paper represents the first attempt in using change detection algorithms for the documentation of the restoration process of a painted artefact, the heritage and archaeological domains have experimented an extensive use of multi-temporal imagery as a useful tool for large-scale protection of monuments, sites and cultural landscapes [ 16 ]. Table  1 presents a literature review concerning the use of 2D change detection algorithms applied in heritage and archaeological science.

3D change detection

In the 3D domain, change detection algorithms ask for three-dimensional models as input data instead of 2D images. These are usually obtained through the state-of-the-art image- and range-based modelling techniques, in forms of point clouds or meshes.

Changes are then usually identified by measuring the distance between 3D models. Four main approaches for distance computation are generally adopted, namely:

DEM of Difference (DoD) [ 25 ];

Direct cloud-to-cloud comparison with closest point technique (C2C) [ 26 ];

Cloud-to-mesh distance or cloud-to-model distance (C2M) [ 27 , 28 , 29 ];

Multiscale Model to Model Cloud Comparison (M32C) [ 30 ].

3D change detection literature review

In Table  2 are summarised some significant examples describing how the aforementioned 3D change detection algorithms, coupled with range- and image-based modelling techniques, can help monitor geometric features of heritage assets over time.

Geometric analysis of paintings

In the field of painting’s conservation, there is a number of non-contact techniques which allow detailed analyses of the artwork’s surface and support in the visible and non-visible spectrum.

In recent years the study and characterisation of artworks’ surface employing different non-invasive digital techniques are quickly evolving [ 38 , 39 , 40 , 41 ]. Typical outputs are usually represented by pigment identification, colour measurements, extraction of geometric features (brush strokes details), and shape’ measurements. Range-based 3D modelling techniques [ 42 , 43 , 44 , 45 ], such as laser scanners and structured light sensors, and image-based 3D modelling technique, such as photogrammetry [ 46 , 47 , 48 ] can provide precise and reliable 3D geometrical and radiometric information useful for detailed analyses and inspections. Both approaches allow the retrieval of very high geometric details with reported spatial resolutions ranging from 60 and 400 μm.

The case study

The artwork used as case study used is a Byzantine icon dating to the 18th century, today exhibited at the Byzantine Museum Archbishop Makarios III Foundation of Nicosia. The wooden panel, originally placed in the church of St. Spyridon in Tremetousia (district of Larnaca, Cyprus), measures 34 cm × 42 cm and represents the bust of the Apostol Peter set against a gold ground. The half-figure of the bearded apostle is depicted looking toward the observer. He is dressed in a blue tunic and a red tint pallium, holding in his right hand the keys and in his left hand a scroll mentioning an extract of the Second General Epistle of Peter (1:1, 1:2) from the New Testament of the Bible (Greek: συμεων πετρος δουλος και αποστολος ιησου χριστου τοις ισοτιμον ημιν λαχουσιν πιστιν εν δικαιοσυνη του θεου ημων και σωτηρος ιησου χριστου;

Translation: Simon Peter, servant and apostle of Jesus Christ, to them that have obtained equal faith with us in the justice of our God and Savior Jesus Christ) .

On the top left and top right corners of the icon, a red abbreviation in Greek says ‘Apostolos Petros’ (Fig.  1 ).

Apostle Petros icon, orthophoto before the restoration

During September 2018 the icon was restored by the Department of Antiquities of Cyprus labs. At a preliminary visual inspection, the icon presented (i) a layer of dark varnish covering all the painted surface; (ii) areas where the colour layer detached entirely from the support and is now missing; and (iii) areas where the colours appeared lifted.

The restoration pipeline adopted by the technicians was following Brandi’s Theory of Restoration [ 49 ], respecting concepts such as the unacceptability of creative conservation and the complete reversibility of any interventions.

An overview of the icon restoration process is summarised in Table  3 .

Digital methodology

The proposed digital methodology consists of four steps: (i) photogrammetric survey, (ii) dense point cloud and orthophoto production, (iii) 2D and 3D multi-temporal change detection, (iv) data interpretation (Fig.  2 ).

Proposed methodology

This approach was tested on a multi-temporal dataset consisting of eleven orthophotos. Each time a conservation task was completed (see Table  3 ), the process was halted, the icon moved in a controlled photographic environment, and the image dataset was collected.

Photogrammetric surveys

The photogrammetric setup consisted of a Canon 5D Mark IV camera, 30-megapixel full-frame sensor (6 mm pixel size), equipped with a Canon EF 24–105 mm f/2.8 USM lens, two photographic lamps, polarised sheets, and polarizes filter. The camera ‘s autofocus was disabled, and the lens focusing ring and Focal Length were fixed at 40 mm with a piece of insulating tape to avoid accidental changes of interior orientation parameters during the photogrammetric survey.

In 3D dense stereo matching, surface reflections may lead to incorrect measurements and blunders in the resulting dense point cloud. The use of a lens polarised filter, oriented in the same polarisation plane, mainly results in a surface enhancement effect, increasing the saturation and contrast of the image. However, with this configuration, the reflections are not eliminated. To overcome the problem of disturbing reflections, polarising filters can be mounted both on the camera lens and on the light source(s). Reflections in the images can be then suppressed by crossing the polarising direction of the filters leading to homogeneously illuminated images and better matching results. To achieve this goal, two polarised sheets were placed over the circular lamps, equipped with fluorescent light bulbs, and rotated accordingly until perpendicular or crossed planes of polarisation were reached.

A few studies have been published concerning the use of polarising films for image-based 3D reconstruction. Table  4 summarises a literature review concerning this topic.

A photogrammetric camera network was a priori planned [ 57 ], following a convergent schema, with the primary aim to guarantee the automated matching of homologous points and an adequate number of intersecting rays [ 58 ] (Fig.  3 ). Given the requirements of sub-millimetre accuracy for 3D geometry, a photographic scale of 1:20 was selected. The icon was placed vertically on an easel, and an estimated camera-object distance of 0.75 m was set, thus resulting in a mean Ground Sample Distance (GSD) of 0.11 mm. An average base-to-depth ratio (B/D) of 0.2 was computed (Fig.  4 ).

Image-data capturing setup

Photogrammetric camera positions

Data post processing

All images, acquired in RAW format, were pre-processed (colour calibration using a colour checker board, histogram’s stretching, and white balancing) in a photo editing software.

The typical photogrammetric workflow was then applied, consisting of three main steps, namely: (i) image correspondences detection, (ii) bundle adjustment and (iii) dense image matching [ 59 ].

Starting from the estimated camera poses and orientation, a dense 3D reconstruction via pixel-based image matching algorithm was applied. This was performed using the first-level image pyramid, corresponding to the original full image resolution. The derived dense point clouds consisted of ~ 3 million points for each single processed dataset. Subsequently, 11 orthomosaics with an average pixel size of 0.2 mm, radiometrically balanced, and digitally blended so that the seam lines between images are not visible, were produced.

With the final goal of fitting the same physical space, each orthophoto was cropped using a photo-editing software preserving the original resolution and GSD. A further refinement of the image alignment was realised co-registering each output as described in “ 2D change detection analysis ” section.

2D change detection analysis

The orthophotos have been processed using the open-source software Orfeo ToolBox (OTB) [ 60 ], a remote sensing image processing library developed by CNES, the French Space Agency.

A three-step strategy was adopted:

first, to refine the image overlap, an initial image co-registration was performed. This application computes a disparity map in 2D between two images that correspond to the same scene. It is intended for the case where small misregistration between images has to be estimated and fixed. The algorithm uses an iterative approach to determine the best match between local patches, and the final output image contains X and Y offsets, as well as the metric value, with sub-pixel accuracy. It is understood that the input images should have the same size (height and width), scale, and occupy the same physical space.

Second, change detection between the orthophotos is performed by adopting the MAD algorithm. A MAD map is thus produced, consisting of three bands that represent the variates (change maps) sorted by increasing correlation.

Finally, the MAF transform is applied to the MAD variates, and the lowest order MAF-MAD component (i.e., the first component) is initially analysed to detect the changes occurred.

Results and discussion

2d change detection data interpretation.

The analysis of the 2D change detection results has been realised by mutually comparing the RGB orthophotos and MAD/MAF change detection maps.

As mentioned in “ 2D change detection ” section, the lowest order MAD-MAF component (i.e., the first component) is initially used to detect the changes that occurred on the icon surface.

Time 0: initial conservation status of the painting

Before the beginning of the restoration process, the conservation status of the icon was assessed through visual analysis. The artefact showed a layer of dark varnish uniformly distributed all over the surface. It was possible to clearly identify areas where (i) the colours were missing such as the left profile of the Apostle’ s face, the hair, the keys, and the vest; (ii) the colour fragments were lifted from the wooden support; (iii) the preparatory layer of gypsum was visible. An image dataset was collected at Time 0 before any physical restoration started (Fig.  1 ).

Time 0–1: cleaning samples

The first step of the restoration process has been represented by testing cleaning agent, diluted in water at different percentages, for the removal of the layer of varnish. Samples have been realised in different areas of the icon in rectangular shapes to assess the most suitable compound. The MAF band 1 map highlights the zones of the icon being cleaned, respectively (i) neck of the Apostle; (ii) left elbow; (iii) bottom part of the scroll; (iv) background area above the scroll (Fig.  5 ). When all the bands (R:1–G:2–B:3) are visualized, it is also possible to distinguish the response given by the different colours of the icon (tunic, pallium, flesh, background), (Fig.  6 ).

Time 0 orthophoto (left), Time 1 orthophoto (centre), MAF Map Band 1 (right)

MAF Map Band R: 1–G:2–B:3

Time 1–2: half icon varnish removal (right side)

After the appropriate cleaning compound was identified, the varnish was removed on the right-hand side of the icon. From the analysis of the change detection map, the new cleaning intervention appears evident, whereas, as expected, the areas previously cleaned (test samples Time 0–1) are not highlighted by the procedure at Time 1–2 (Fig.  7 ).

Time 1 orthophoto (left), Time 2 orthophoto (centre), MAF Map Band 1 (right)

Time 2–3: half icon varnish removal (left side)

According to the results achieved in the previous step, also the left-hand side of the icon was cleaned. All the varnish visible at the beginning of the restoration process was removed. The MAF results are consistent with what has been already observed during the analysis of the change detection in Time 1–2 (Fig.  8 ).

Time 2 orthophoto (left), Time 3 orthophoto (centre), MAF Map Band 1 (right)

Time 3–4: initial retouching of the head profile, keys, and scroll

After the complete varnish removal, the lacunae integration of the icon was initiated. Firstly, a neutral and uniform colour forming the preparatory layer was applied to the areas of the head/face profile, keys, and scroll. The MAF band 1 map pinpoints the extents affected by these interventions, confirmed by the subsequent exam of the RGB photos (Fig.  9 ).

Time 3 orthophoto (left), Time 4 orthophoto (centre), MAF Map Band 1 (right)

Time 4–5/5–6/6–7: retouching of the shoulders profile and bottom of the scroll; retouching over the pallium (right); retouching over the pallium (left)

The restoration procedure described above (Time 4) continued at Time 5, 6, 7. The interventions regarded different areas of the icon such as the profile of the shoulders (Fig.  10 ) and the small gaps on the pallium which have been recorded to underline the efficacy of the proposed methodology (Fig.  11 ).

Time 4 orthophoto (left), Time 5 orthophoto (centre), MAF Map Band 1 (right)

Time 5 orthophoto (left), Time 6 orthophoto (centre), MAF Map Band 1 (right)

After the analysis of the MAD/MAF maps, it was possible to isolate different radiometric responses regarding the application of colours (black value and white value) according to the modification occurred (painting integration over (i) the gold background; (ii) the gypsum layer or (iii) the pre-existing colours). However, these data need a more in-depth analysis through additional case studies.

It has also been observed that different bands of the MAF map highlight different kind of changes occurred on the icon surface. At Time 6–7, band 1 of the MAF map showed a small lacunae integration occurred on the shoulder of Saint Peter (Fig.  12 ), whereas MAF band 0 map, showed the intervention concerning the face of the Apostle where an additional layer of neutral colour was applied (Time 7) (Fig.  13 ).

Time 6 orthophoto (left), Time 7 orthophoto (centre), MAF Map Band 1 (right)

Time 6–7 MAF Map Band 0

Time 7–Time 8/Time 8–Time 9: retouching on the head (beard and hair); retouching on the keys and additional details on pallium and head

As described above, the integration of missing parts of the icon, when the colour was applied on top of a pre-existing one, returned a unique value (white) throughout the survey.

Time 8 and Time 9 change detection analysis undoubtedly shows areas where the retouching, using the rigatino technique, was realised above layers of neutral colours applied in earlier phases of the restoration (Time 4) (Fig.  14 ).

Time 7 orthophoto (left), Time 8 orthophoto (centre), MAF Map Band 1 (right)

In Time 8 and Time 9 series it is possible to identify interventions on the keys, the tunic (Fig.  15 ) and small refinement on the Apostle face and hair (lower part), cheekbone (Fig.  16 ) and the upper side of the head.

Time 8 orthophoto (left), Time 9 orthophoto (centre), MAF Map Band 1 (right)

Time 8 orthophoto detail (left), Time 9 orthophoto detail (centre), MAF Map Band 1 detail (right)

Time 9–Time 10: retouching on the scroll, keys, and tunic; retouching on the gold background

Time 10 was the last image dataset acquired at the end of the restoration process. The interventions, as shown by the MAD/MAF produced map, were focused on the red Greek inscription on the right upper corner, the scroll, the small details of the keys, head profile and the lacunae on the gold background. However, the resulting map highlighted the importance of a correct and rigorous photographic setup. A non-correct orientation of the polarised filters can indeed lead to illumination anomalies, as shown on the edge of the right-hand side of the icon (Fig.  17 ).

Time 9 orthophoto (left), Time 10 orthophoto (centre), MAF Map Band 1 (right)

3D change detection analysis

The MAD/MAF change detection approach identifies modifications only in two-dimensional space (Fig.  18 describes the MAF map Time 1–Time 10, showing the global changes after the restoration process). A 3D change detection algorithm was then used to (i) assess if any geometric variation of the surface, before (Time 0) and after (Time 10) the restoration, could be highlighted; and (ii) evaluate the responsiveness of the 3D change detection algorithm dealing with sub-millimetric variations.

MAD/MAF map showing the changes occurred at the end of the icon conservation process (cleaning, consolidation, and retouching)

Time 1 and Time 10 point clouds, each consisting of an average of 3 million points, and featuring a point resolution in X and Y of 0.11 mm, were registered exploiting an Iterative Closest Point (ICP) algorithm. The alignment process returned an RMSE of 0.09 mm. Subsequently, a cloud-to-cloud signed distances map was computed adopting M3C2 plug-in. This algorithm, implemented in the open source software CloudCompare [ 61 ], performs a direct comparison of point clouds in 3D, thus avoiding the preliminary phase of meshing or gridding. The output was represented by a colour-coded point cloud which highlighted values in the magnitude of ± 0.5 mm (Fig.  19 ).

Distance M3C2 (mm) between Time 0 and Time 10 dense point clouds

The M3C2 outcome can be explained assuming the removal of the layer of varnish which was covering the icon before the conservation process was initiated. The varnish could be indeed represented by the positive values ranging from 0.0 to 0.2 mm. However, this hypothesis must be confirmed with additional case studies.

Shape analysis

The produced 3D dense point cloud (Time 10) was finally inspected and analysed to identify any features concerning the wooden support not directly noticeable during the initial visual inspection. Assuming the original planarity of the wooden support, the icon did not show any apparent deformation. Some shading algorithms were then applied to enhance hidden characteristics, and a best fitting plane analysis was run (Fig.  20 ) achieving an RMSE of 0.6 mm between the plane and the icon surface. The result shows a slight deviation which reaches its negative peak on the lower left- and right-up corners (5 mm), and positive peak on the central area (2 mm) for a maximum absolute range of about 7 mm (the entire icon spans ca 340 × 420 mm). Further 3D shape analysis will be performed in the future to control the geometric behaviour of the icon over time, and to asses if the appropriate conservation conditions, in terms of environmental variables such as temperature and relative humidity which might effect the wooden support, are in place.

3D coordinates of the photogrammetric dense point cloud coded according to the distances from the least square plane computed on the painting surface (mm)

The article reported an extremely promising study, and first of its nature according to the author knowledge, on the use of change detection algorithms in combination with photogrammetry for an efficient, non-invasive systematic multi-temporal documentation and monitoring of the restoration process of a painted surface.

The benefits of recording all the step of the conservation procedure, from macro changes to fine details, have been highlighted under the reversibility principle proposed in Brandi’s Theory of Restoration, which includes the last possibility of bringing the artwork back to its original status - quo - ante. Thanks to the fast and contactless photogrammetric protocol for the image data collection, the proposed methodology can be easily integrated into almost every conservation project (indoor and outdoor) without hampering the delicate steps of the restoration itself. After the initial parameters are set, and according to the typology and scale of the artefact, images can be acquired, and subsequently processed.

Because of the multiplicity of the data generated through photogrammetric techniques, it was also possible to perform a 3D study and assess the Byzantine icon geometric features before and after the restoration process. The latter included a shape analysis of the wooden support for the identification of not visible deformation patterns.

From a methodological point of view, the study underlined the importance of a correct light setup and the need of constant and uniform illumination, with the primary aim of avoiding radiometric artefacts which could impede the photogrammetric reconstruction and the identification of all the restoration phases during the change detection procedure. Moreover, the correct alignment of each image dataset has to be as accurate as possible to avoid errors.

Although the MAD/MAF map contains a high degree of details, its combination with different spectral bands and RGB data, supported by the user experience, still provide the most reliable and accurate source of semantic data interpretation.

Nevertheless, the test was successful in delivering results compatible with the restoration logs.

The described workflow, applied here for the first time to painted surfaces, can be largely used in the heritage science domain. The fields which could mainly benefit are foreseen to be those dealing with monitoring issues such as frescoes (indoor and outdoor), buildings [ 62 ], and all those heritage assets which are exposed to decay due to the incorrect conservation conditions (environmental parameters such as temperature and humidity; pollution; natural and man-made threats).

Abbreviations

Geographical Information System

Multivariate Alteration Detection

Canonical Correlation Analysis

Maximum Autocorrelation Factor

DEM of Difference

cloud-to-cloud comparison

cloud-to-mesh distance or cloud-to-model distance

Iterative Closest Point

Multiscale Model to Model Cloud Comparison

Ground Sample Distance

base-to-depth ratio

Orfeo ToolBox

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Authors’ contributions

DA: Lead researcher who carried out the research project and wrote this publication. The author read and approved the final manuscript.

Acknowledgements

The author wishes to thank the Byzantine Museum (Archbishop Makarios III Foundation) of Nicosia lead by Dr. Ioannis Eliades where the icon analysed for this study is currently conserved. He would also like to express his great appreciation to the Department of Antiquities of Cyprus, in the person of its Director Dr. Marina Solomidou-Ieronymidou, for the permission to undertake the research presented, and especially to Ms. Dora Matar for the patience and support provided during the restoration process and imaging data collection.

Competing interests

The author declares no competing interests.

Availability of data and materials

The datasets generated and/or analysed during the current study are not publicly available due limitations of the sharing of the data by both the Cyprus Institute and Departments of Antiquity of Cyprus but are available from the corresponding author on reasonable request.

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Abate, D. Documentation of paintings restoration through photogrammetry and change detection algorithms. Herit Sci 7 , 13 (2019). https://doi.org/10.1186/s40494-019-0257-y

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Published : 05 March 2019

DOI : https://doi.org/10.1186/s40494-019-0257-y

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Reproducing paintings that make an impression

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The empty frames hanging inside the Isabella Stewart Gardner Museum serve as a tangible reminder of the world’s biggest unsolved art heist. While the original masterpieces may never be recovered, a team from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) might be able to help, with a new system aimed at designing reproductions of paintings.

RePaint uses a combination of 3-D printing and deep learning to authentically recreate favorite paintings — regardless of different lighting conditions or placement. RePaint could be used to remake artwork for a home, protect originals from wear and tear in museums, or even help companies create prints and postcards of historical pieces.

“If you just reproduce the color of a painting as it looks in the gallery, it might look different in your home,” says Changil Kim, one of the authors on a new paper about the system, which will be presented at ACM SIGGRAPH Asia in December. “Our system works under any lighting condition, which shows a far greater color reproduction capability than almost any other previous work.”

To test RePaint, the team reproduced a number of oil paintings created by an artist collaborator. The team found that RePaint was more than four times more accurate than state-of-the-art physical models at creating the exact color shades for different artworks.

At this time the reproductions are only about the size of a business card, due to the time-costly nature of printing. In the future the team expects that more advanced, commercial 3-D printers could help with making larger paintings more efficiently.

While 2-D printers are most commonly used for reproducing paintings, they have a fixed set of just four inks (cyan, magenta, yellow, and black). The researchers, however, found a better way to capture a fuller spectrum of Degas and Dali. They used a special technique they call “color-contoning,” which involves using a 3-D printer and 10 different transparent inks stacked in very thin layers, much like the wafers and chocolate in a Kit-Kat bar. They combined their method with a decades-old technique called half-toning, where an image is created by lots of little colored dots rather than continuous tones. Combining these, the team says, better captured the nuances of the colors.

With a larger color scope to work with, the question of what inks to use for which paintings still remained. Instead of using more laborious physical approaches, the team trained a deep-learning model to predict the optimal stack of different inks. Once the system had a handle on that, they fed in images of paintings and used the model to determine what colors should be used in what particular areas for specific paintings.

Despite the progress so far, the team says they have a few improvements to make before they can whip up a dazzling duplicate of “Starry Night.” For example, mechanical engineer Mike Foshey said they couldn’t completely reproduce certain colors like cobalt blue due to a limited ink library. In the future they plan to expand this library, as well as create a painting-specific algorithm for selecting inks, he says. They also can hope to achieve better detail to account for aspects like surface texture and reflection, so that they can achieve specific effects such as glossy and matte finishes.

“The value of fine art has rapidly increased in recent years, so there’s an increased tendency for it to be locked up in warehouses away from the public eye,” says Foshey. “We’re building the technology to reverse this trend, and to create inexpensive and accurate reproductions that can be enjoyed by all.”

Kim and Foshey worked on the system alongside lead author Liang Shi; MIT professor Wojciech Matusik; former MIT postdoc Vahid Babaei, now Group Leader at Max Planck Institute of Informatics; Princeton University computer science professor Szymon Rusinkiewicz; and former MIT postdoc Pitchaya Sitthi-Amorn, who is now a lecturer at Chulalongkorn University in Bangkok, Thailand.

This work is supported in part by the National Science Foundation.

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CSAIL researchers have developed a new technique to recreate paintings from a single photograph, reports John Biggs for TechCrunch . “The project uses machine learning to recreate the exact colors of each painting and then prints it using a high-end 3D printer that can output thousands of colors using half-toning,” Biggs explains.

Fast Company

Fast Company reporter Jesus Diaz writes that CSAIL researchers have developed a new technique to replicate works of art. Diaz explains that the system “uses a combination of 10 different transparent inks, placed by a 3D printer and governed by a complex AI system that decides how to layer and mix those inks to match a painting’s original colors.”

Forbes contributed Jennifer Kite-Powell writes about a system, called RePaint, developed by MIT researchers that uses AI and 3-D printing to replicate paintings. "We can picture RePaint being applied to restoration practice and education in museums so that greater numbers of people could be exposed to famous pieces of art beyond just the specific museums that house them," explains CSAIL mechanical engineer Mike Foshey.

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Worlds Most Beautiful Painting are here!

Art restoration: the process and challenges of restoring damaged paintings..

• Post comments: 1 Comment
• Reading time: 17 mins read

Table of Contents

What is art restoration?

Though only a tiny fraction of museum collections have been damaged or destroyed by fire, floods, theft, or other accidents, it is nevertheless a pressing problem. Museums are legally bound to keep their collections in good condition, and when a fire or a burglary destroys works, they are faced with the difficult decision of whether and to what extent to replace or restore them, perhaps at great expense.

Art restoration is a highly skilled field, requiring not only years of training, but a good eye, a good memory, and a strong stomach. The task is complicated by the fact that even a minor accident can destroy the art’s historical, scientific, or artistic value.

The restoration of damaged works of art is a task that museums not only take on themselves but are constantly trying to get better at. The Metropolitan Museum of Art has an active program devoted to cleaning, repairing, and conserving its collection. The National Gallery of Art and the Smithsonian Institution’s museums have similar programs.

Most museum conservators work to preserve works of art, but once in a while, they get a call to restore something, too.

What are the challenges of restoring a painting?

Today, when art restoration is more commonly referred to by its technical term, conservation, it is most commonly concerned with paintings. But paintings are only the best known of a number of media that have been damaged by both time and environmental factors.

The Metropolitan Museum of Art, where conservation work is concentrated, ranges from small objects to monumental sculptures. While the conservation staff has trained to work on every medium, the artists who create them have also brought a level of expertise to the process.

The Met’s conservation scientists consider art conservation to be essentially three processes: 

• preventive conservation 
• research and education. 

Treatment is the actual process, with materials and techniques, necessary to restore an object. Preventive conservation involves eliminating or reducing threats to objects before they occur. Educational and research are designed to support treatment and preventive conservation.

The Met’s conservation department’s laboratories are not open to the public, and conservators are proud to keep it that way. They like to show off their work, but not their methods.

Conservation scientists and conservators work closely with Met’s curators, especially in conservation research, preventive conservation, and public education.

What are the different types of art restoration?

For 500 years, art was thought of as something that could not be restored, and this sense of permanence was reinforced by museums, which treat their collections as sacred. (Museums used to be called “temples,” and they are still temples.)

Over the last 30 years, however, it has become clear that we can restore almost everything.

For example, we can restore paintings by wiping off dirt, wax, and other accumulations and replacing missing parts.

We can fix the sculpture by mounting it on fiberglass and, if necessary, filling in missing bits.

We can regain jewelry by polishing it, replacing missing stones, and replacing parts that have fallen off.

We can restore ceramics by cleaning them, filling cracks, and gluing broken pieces.

We can restore glass by cleaning it, replacing missing pieces, and repairing cracks.

We can restore paper by cleaning it, replacing missing parts, and repairing tears.

We can restore wood by sanding it down, filling cracks and holes, and varnishing it.

We can restore textiles by cleaning them and, if necessary, replacing missing parts.

We can restore leather by cleaning it, replacing missing pieces, and repairing tears.

We can restore metal by cleaning it, replacing missing pieces, and repairing dents.

We can restore paper by cleaning it

Challenges of restoring damaged paintings

Paintings are fragile. They fade and discolor, and if they are old, they sometimes develop cracks. Depending on how they have been damaged, restoration can be a simple or a complex process. The simplest restoration is retouching. Sometimes the damage is so small that paint can be brushed on to cover it. Some damage, however, is too deep to be retouched. When a painting has been folded repeatedly or exposed to extremes of temperature, the canvas loses its flexibility.

Repairing an old oil-on-canvas painting can be tricky. Large tears, punctured holes, and flaking paint are obvious problems that you will need to deal with. Smaller damages, however, can often just be retouched if the canvas is still flexible. Many ancient paintings have been folded repeatedly over the years or taken out of their frames for cleaning or other repairs.

Restoring a painting requires a thorough examination of the original surface. Old, faded paintings may need to be cleaned, and cracks in the paint may have to be repaired. In paintings that have been rolled or folded, folds can become permanent or even tear through the canvas. Sometimes painting over a badly damaged surface simply doesn’t work, and if a repair is made, you will always be able to tell where it took place.

What exactly does an art restorer do?

Art restoration is becoming one of the fastest-growing fields in the art world.

This field has been expanding for two reasons. First, many famous works of art are damaged by time; the ravages of weather, neglect, and accidents are so great that few museums can afford to have them restored. 

Second, many art museums now feel obliged to save more artwork than they can display, and so hire restorers to catalog, clean, and conserve the pieces that the institution already owns.

Of all the skills required for art restoration, perhaps the most vital is the ability to discriminate between damage and deterioration. The difference between dust and grime and decay or damage can be subtle, and a professional restorer is trained to look for it.

Professional restorers also have to deal with things that most people would never even dream of touching. The restorer who was hired for the painting on the ceiling of the Sistine Chapel, for example, had to reattach every little piece of tesserae, the tiny fragments of colored stone that made up the mosaic.

And restorers need to be able to read the problem, not the labels. For instance, a restorer who was hired to clean and conserve a painting by Rembrandt was not simply removing dirt. The work she was doing was cleaning layers of paint that had been applied over centuries, layers that had gradually yellowed and darkened.

The restorer had to decide what paint remained; she had to decide whether it was the original paint or overpainting or overpainting that the restorer should remove. And she had to decide what color was underneath.

Restoration is as subjective as art itself, and just as difficult. 

What is the process of restoring a painting?

Art restoration is a fascinating job but not many people know what it is like. It is a bit like being a detective, except that instead of solving crimes, you are trying to figure out which paint layers were put on by an artist and which were added later by someone else.

The paintings usually under restoration are paintings on canvas. Paintings on wood or parchment are harder to restore than paintings on glass or metallic surfaces.

The job of restoration begins when the painting is discovered and it is identified. Sometimes a painting will be identified from a photograph; sometimes it will be identified by its style.

The next step is to try to figure out when the painting was made. Often it has a date. If it is old, the date may be the best guess, or it may be based on research. A date of 1600, for example, is pretty much as good as the date of 1600. A date of 1600, 1605, or 1600, 1606, is about the same, and a date of 1600-1605 is just as good.

Knowing when the painting was made isn’t enough. You may have a good guess, but how do you know it is right?

The first step is to look for the name of someone associated with the creation of the painting. Sometimes paintings are signed, and the signature tells you something. A signed portrait by Rembrandt, for example, means that the portrait is by Rembrandt. Sometimes a signature tells you nothing. Most signed paintings weren’t signed when they were made; they were added later, as was common practice in the seventeenth century.

Next, look for clues in the painting itself. Paintings often show things in the background that are the same as other things in the background of other paintings. 

There are two basic approaches: one invites the artist’s eye to take over, the other tries to restore the original.

We usually think of artists as having the genius to create something new. They don’t. They usually try to restore what already existed, and they do it more or less successfully. And the way artists restore is not by thinking about the painting itself but how to restore it. 

They go to the museum; they look at the paintings; they look at all the paintings that are similar to theirs; they look at what those paintings look like today. Then they bring back all the things that they like — the paint, the colors, the composition, the framing, whatever — and they try to use it to make something new. They have some idea of how to restore a painting, and they usually get it right.

The difference between restoration and creation is that creation is risky. No matter how good you are, you can’t foresee what something will look like. You can predict what something will look like from how it was before, but even that is not enough. Often the original artist did not know exactly what he was creating. He was experimenting. When he finished, he would have had no idea what it looked like. Thus the creation, by its very nature, is riskier than restoration.

All of which makes it all the more surprising that artists work so hard at it. It is safer to try again to restore a painting than to create something new.

Art restoration is more interesting, though than art creation. 

The artist’s eye is very powerful. But it can’t always tell you what is wrong. It can tell you what is wrong with a painting you have never seen before, but it can’t tell you what is wrong with a painting you have seen before. And it can’t tell you what is wrong in anything.

The only way to know for sure what is wrong is to look at the thing itself

How does an expert restore paintings?

The job of a restorer is to put things back the way they were. If, for example, you decided to throw a party, and a lot of your friends showed up, you would probably clean up some tables and chairs, clear some space, and put them away. You would not invent new tables and chairs, hang a fresh coat of paint on the walls, or bring in unique decorations. Instead, you would restore the old stuff to the way it was before you had people over.

A restorer is a person who does the same thing with art.

But restoration doesn’t work if you just put things back the way they were. If a painting restorationist saw a painting with a hole in it, it would make no sense to put another painting on top, even if it was exactly the same size and shape. Instead, the restorer would figure out which color was in the original painting and mix and paint a new panel to match.

Restoration also doesn’t work if you restore a work without exploring alternatives. Suppose a restorer had never seen another copy of a painting. He would not know that a painter had once painted a second version of the same scene and that both of them looked fine. In fact, the second painting would look better.

So restoration requires good judgment about what to change and imagination about what could be changed.

The restorer also needs a good understanding of the original. He needs to be able to tell from the existing painting what the original painting was like. He needs to know when it was made, and what was popular at that time. And he needs to understand the techniques of the original painter.

But whatever the restorer knows about the original, he almost never gets to see the original. 

How do you know if your art or painting needs to be restored?

When you look at a painting, you’re seeing the surface. The painting is made up from multiple layers of paint. Each layer has a different purpose. Some are there to protect the paint underneath, some to make the paint lie flat, some to make the paint reflect light, some to make the paint look shiny, some to make the paint look dull, some to make the paint look gritty, and so on.

So when you look at the surface of a painting, what you’re looking at is a combination of different purposes.

Now let’s say that some of the paint layers are old, and some of them are new. These new layers have fresh purposes. But the old layers are still there. They have served their purpose, and now it’s time to get rid of them. Art restoration is the process of doing just that.

The job of art restorers is to figure out what those old layers were for, and then to get rid of them. There are different techniques for removing different kinds of paint. Some are better for removing old layers of oil paint than for new layers of acrylic paint, and vice-versa. Some are better for getting rid of black than for getting rid of the color.

But how do you know whether a painting is old? Sometimes you can tell. Sometimes the paint is flaking; sometimes you can see the layers of paint in the cracks between the glazes on the canvas. But sometimes you can’t.

Sometimes you can tell just by looking at it. Sometimes you can tell just by touching it. But not always. And sometimes you can’t.

The restoration supplies you will need

You are going to restore a 16th-century painting. You have two painting boards, each with a scale of 1/8 inch, a brush, a cleaning cloth, two cloths of turpentine, a tray, two bottles of linseed oil, and a bottle of varnish.

Is all of this stuff really necessary?

Well, no. If you don’t have the painting boards, you can measure the painting with a piece of string. The paint on the string won’t match the painting, but it will do in a pinch. If you don’t have the brush, you can scrape the paint off with a razor blade.

But you aren’t going to get a very good job that way. So let’s assume you have everything.

The painting is 5.5 inches by 3.5 inches. It is covered with a layer of paint about 1/16 inch thick. The surface has few breaks — the brush marks are shallow and straight. The paint is brown, light brown, tan, and ivory.

Here is your shopping list:

• 1. turpentine, 1 ounce
• 2. linseed oil, 1 ounce
• 3. varnish, 1 ounce
• 4. brush, 12 inches
• 5. painting board, 1/8 inch
• 6. measuring tape, 4 inches
• 7. razor blade
• 9. flat brush
• 10. small brush

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This post has one comment.

It’s nice that you talked about how art restoration is a highly skilled field, requiring not only years of training, but a good eye, a good memory, and a strong stomach. I was watching an educational program last night and I was quite amazed to see how some professionals restored various famous art pieces. Also, from what I’ve heard, it seems art restoration is being offered by some companies now too.

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Art Conservation and Restoration

• Last Updated: Nov 2, 2023 1:12 PM
• URL: https://libguides.mhs.vic.edu.au/artconservation

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Manual on the conservation and restoration of paintings.

Type: Publication

Place, publisher, year: Paris : International Institute of Intellectual Co-operation, 1940

Collation: 296 p. ; illus. ; 23,5 cm

Author: Foundoukidis, Euripid (préf.)

Author corporate: International Museums Office (OIM)

Year: 1940.

Serial type: Book - Monograph - Document

Description: conservation; restoration; paintings.