For art's sake:
Detect original and fake works

by Renate Kant

First appeared in The Jakarta Post, 29 April 2001

SINGAPORE (JP): On Sunday, March 18, 2001, The Jakarta Post ran an entire  section of articles about art forgery with such titles as "Forged Art a Lucrative Business", "Indonesia, the Land of Fine Art Forgery" and "Forgery, Crime Plaguing Art World".

Cross-section of base, paint and varnish layers on a painting at 140x enlargement

Excellent coverage on an important issue. In all articles, however, an  important component to this discussion was omitted, a critical piece of the puzzle to help determine the authenticity of a painting: a professionally  trained painting conservator and restorer has learned the skills to detect  original and faked works.

Art forgery is as old as the history of art itself. Already in ancient Greece, there were excellent studios working with the intention to pretend authenticity.

Most of these works of art -- for example, on paper, metal work, ceramic and  paintings on panels as well as canvas -- were created to purposely manipulate the original artifact. It is well known that in nearly all important museum collections, sometimes after years, fake paintings are discovered which formerly represented the icons of the exhibition rooms.

Their detection is not easy, as the aging of the materials over a time span of centuries does not allow at once to authenticate questionable works. Only  laboratory research together with stylistic comparisons in archives and collections with undoubtable provenance could mostly help to verify suspicious products.

Thomas Hoving, a former director of the Metropolitan Museum of Art and an active fake buster, estimates that "a startling 40 percent of the art in the market are either half-forgeries -- genuinely old works that have to be doctored to fit a more valuable styleor artists -- or are outright fakes.

Visual observation

Astri Wright, a Canadian-based art historian was quoted as saying that the "experienced eye of someone trained in art history can pick up these signs" of nuance of color, type of paint and canvas used and other detail and features. I agree that a trained eye can do this but in my 30+ years of experience working with paintings of all media I have learned that art historians as well as curators, art aficionados and artists themselves are very often at a complete loss when manipulations have done to a painting.

The eye of an art historian can be very useful, but regarding the technological examination, I believe that she or he can be easily misguided by aesthetic and theoretical reasons. However, as the paintings we are facing in Southeast Asia are in general at the most 80 years old, it is easier to determine chronological traces of the deterioration process by  aging through a rough comparison of the artist's work over several periods or through research on paintings from the same timespan. By no means can a work of Sudjojono or Hendra done in l960 be faked without detection. Traces of this manipulation can always be investigated.

Manipulation

What is meant by manipulation? Relining, for example, and infusion of patinas (oil, glue) from the reverse side can cover original traces. The use of tinted varnish may not allow reflection of changes of composition in  ultraviolet light. Parts of overpainted damages and sections of thinned and overcleaned areas may have disturbed the painted images.

Recycled canvasses and patches may have been used to stimulate an aged torn canvas, or abrasion can be used to artificially simulate the aging process. There are many other tricks of the forger trade to apply touch-ups only in minor unimportant parts of the composition to pretend that the main that the main work is nearly oven-fresh.

These manipulated "damaged parts" can be covered with nonreflecting tinted natural or synthetic coatings, a practice often used in Europe, for example, when a historic painting of the 17th or 18th century comes on the market. A  professional conservator immediately will examine changes of pigments, diminished glazings, oxidated varnish layers, under the overpainted coatings, etc.

I agree with Watie Moerani, head of the National Gallery Jakarta, that "We  feel like soldiers without weapons in fighting art forgery" because there are few trained and experienced conservators and restorers who can approach  the doubtful pieces with a solid practical analysis on the micro level. Visual analysis of works together with laboratory research is most effective.

Laboratory research

With the great advances made in the last decades in our understanding of how chemical reaction takes place and how the chemical systems can be identified, descriptions of deterioration in terms of the process of  activation and chemical changes that occur has nowadays almost subconsciously entered into the polymer chemist's day-to-day language.

The questions have to be clearly asked by the conservators and I have experienced that well-trained chemists can demonstrate and confirm beyond much doubts the mechanism of the chemical steps in these challenging tasks.

The following research criteria must be considered to discover more details that are hidden from the naked eye. There are the new tools to detect  fool-proofed faked works.

Conservators can more easily tell the authenticity and the aging of  materials when statistical laboratory test results can be compared with similar findings from other works by the series artists. Varnish and paint  layers, for example, can be determined in their aging (the oxidation of  paint layers) by gas chromatography. Cross sections of the painting will show similarities with authentic works. Analysis of binding media and the concept of composition or compositional changes can be shown in infra red reflectography.

Even when historical materials are used (and which "professional" forger will apply synthetic titanium white, industrially produced since the beginning of this century, on a still-life of the 18th century instead of a metallic lead white well known to a darken as a photochemical result?) the chemical changes that occur within a material are the criteria conservators and laboratories have to determine.

But the critical physical changes as well, such as loss of tensile strength,  adhesive strength and folding endurance always have to be related to the chemical tests. For example, there are true indicators that show whether change of chemical reactions happen that allow judgment about the aging of  material.

One particular test indicates the percentage of insoluble matter in a coating and its ease of removal in solvent, the ability to swell, insolubility, and the polarity of solvent required to evaluate the onset of an unacceptable degree of difficulty in removal of a picture varnish.

In another example, the measurement of yellowness in a film may not closely  relate to insolubility or brittleness. This yellowness by photchemical and  thermal aspects often shows the authenticity of the age of a painting;  however, the principle chemical changes that occur within the material  always have to be tested in their reactions.

UV light tests can show traces of underpaint or changes of composition. Natural science tests can be utilized such as chemical binding media analysis, pigment analysis and material endurance tests to prove the authentic stability of the media.

Underpainted areas on board can be detected by x-ray and computer tomography.

Examples

For example, I started to take macrospecimens from the painting I restored of the famous Indonesian painter Raden Saleh and conducted tests in a German  laboratory. The aim is to code his specific choice of painting material in order to build up a record of statistics. The specimens are cast in synthetic resin and undergo microscopic research up to 140x enlargement with and without UV light impact.

They provide proof for Raden Saleh's statement in one of his letters that he used tinted varnishes as final coatings because "they have to look like  bacon or smoke."

For the 60 Hendras and 19 Le Mayeurs I have restored to date, similar observations have been collected, but due to investment reasons the specific analyses by natural science laboratories had to be postponed.

When auction houses, public or private collectors ask for a consultation, a conservator will give them a detailed report about solvent tests, light reflection of coatings, aging of materials and traces of possible  manipulated changes. The stylistic arguments are always important as a second approach. My experience is that a well-respected auction house will  pull the painting back.

It is indeed a crime to forge a painting with the intent to sell it off as an original. Art is an investment, and because large sums can be spent on the work of artists considered already to be of major value, it is more important than ever to have each doubtful work examined and verified as to its authenticity. I applaud all integrated efforts along these lines.