Who doesn’t like that thriller of a movie, “The Thomas Crown Affair”, where a famous painting is stolen from the Met in NYC, and later returned by the thief. But, did you ever wonder how in the world museums are able to authenticate art pieces? If you found a wonderful painting, in the Impressionist style, while cleaning out Aunt Sylvia’s attic, how would you go about determining the origin and authenticity of your find?
The answer lies in the field of forensic science. The same instruments used to identify automotive paint in cases of vehicular homicide, that wand they wave over you in the airport to detect explosives residue, and the X-rays used to scan luggage at that same airport, are used to determine the provenance of an art piece.
Provenance, a French word, meaning the place or source of origin, is what art historians and curators give to an object d’arte when they are through analyzing it. As you can imagine, the more science has developed analysis techniques, the longer the list of tests that an art work is subjected to. Let’s start with the canvas itself. Obviously the material that the canvas is made of can be helpful. If the threads in the canvas are synthetic, we know this is not a Rembrandt.
The paint and other media the artist used is one of the best indicators of authenticity. Before Grumbacher started mass producing and selling art supplies, artists made their own primers, paints and preservatives. Many of these recipes were guarded secrets. Many were also highly toxic. If you remember the book or movie, “The Name of the Rose” by Umberto Eco, it was the monk’s ink that done him in.
Paint can be analyzed by using a separation technique known as gas chromatography. This very delicate instrument will create a palette of colors that go into making up that particular paint. The kind and amount of individual pigments in the paint are like a fingerprint. This technique is also used to identify the make of an auto used in a crime, from its paint profile, using chromatography.
Another more sensitive method of analysis is Neutron Activation Analysis. This technique can detect the isotopes of elements found in the paint. An isotope of an element is a form of that element that differs in the number of neutrons in its atoms. Paint has elements like chrome for chromium yellow, or cadmium for cadmium red, or cobalt for cobalt blue. Each of those elements has isotopes depending upon the source of the element. So if Titian developed his famous red color from a particular cadmium source, the number and kind of isotopes would differ from cadmium from a different cadmium ore from another location. Thus, the analysis yields a profile of the isotopes that is another kind of fingerprint.
Another way to analyze the painting is to subject it to infrared radiation. The elements in the paints absorb infrared at different frequencies, and the resulting reflectogram shows if there are paintings underneath the one we see, and can often tell how the artist altered the painting as he progressed to the completed product. Artists often had to be frugal, and painted over existing canvases. A simple X-ray like the one used to detect a broken leg, can reveal layers of paintings on a canvas.
The obvious detection of modern materials like acrylics in the paint will make it clear we are not dealing with a work produced before the development of such materials.
Handwriting analysis comes to play if the artist signed the painting. Handwriting analysis is a well-developed art, but so is forgery. Rembrandt was so sought after by the wealthy Dutch that he was known to start a portrait, and have it completed by one of his apprentices, only to sign it when it was finished. We will never know.
Art historians usually put the finishing touches on the analysis of a painting. Brush stroke and technique are as individual to artists as their fingerprints. Art historians become experts at detecting these “styles”. In the final analysis, unless the scientific tests we’ve mentioned prove otherwise, it is the historian who gives their imprimatur to the work.
To find out some interesting facts about famous art forgeries visit: http://www.livescience.com/19518-famous-art-forgers.html
http://www.huffingtonpost.com/2013/08/05/art-forgery-exhibit_n_3696341.html
To view some interesting activities related to the scientific analysis of art works, visit: www.annietillery.com, click on lesson plans for “Girl with Pencil, Drawing”.
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