An art collector, who owned a painting purchased by a family member from an art gallery in Europe just before the German invasion of Paris, contacted RJ Lee Group to determine when the painting had been created. The painting was signed by a well-known early 20th century artist and was true to the artist’s style, but it was not listed in the artist’s portfolio of known works. The owner wanted to determine if the painting could be the work of this artist based on its age. Our mission was to establish a timeframe in which the painting could have been created by investigating the pigments and other materials used and examining the construction of the painting.
The Perfect White
Throughout the years, artists have been known to prepare or repurpose canvases by “grounding” them or applying a preparation layer of primer to them, to prevent absorption of paint into the canvas. Since World War II, the preferred primer has been titanium (Ti) (anatase or rutile), called titanium white, because of its covering power, brightness, very high refractive index, opaqueness and because it is non-toxic. As we examined the painting, this underlying or grounding layer could be seen through cracks in the painting’s background. To determine the exact method used to prepare the canvas, we enlisted the aid of local painting conservator, Ms. Rikke Foulke of Foulke Fine Art Conservation LLC. By examining the painting’s construction, she was able to establish that our canvas was not commercially prepared, but that the white layer had been applied by the artist. Having uncovered this fact, we now needed to assess the age of the canvas by determining if titanium white was present in the grounding layer. Since the artist died before titanium white was commercially used as a pigment, the absence of this pigment would be a factor in determining the age of the painting.
Non-Destructive Investigative Techniques
RJ Lee Group scientists used two non-destructive, independent analytical techniques to determine the presence of titanium: X-ray fluorescence (XRF) and Raman spectroscopy. The portable XRF uses x-rays to determine the presence and amount of elemental titanium, while the portable Raman uses laser light to determine which form (anatase or rutile) of titanium dioxide (TiO2) is present.
We conducted XRF analyses at 10 locations on the painting using the same parameters and conditions. Each analysis was two minutes in length. The spectra and raw data were saved to the portable XRF after each analysis and later downloaded to a computer for review. Using that data, we determined that titanium was not present at any of the locations evaluated.
Raman spectroscopy provides a distinct chemical fingerprint for each molecule or material and can be used to very quickly identify it or distinguish it from others. Our Raman included a library of more than 7,000 spectra for identification of unknown compounds. We collected spectra for each of six spectral locations and none of the collected spectra matched either form of titanium dioxide.
Industrial Forensics Provides Conclusive Evidence
By combining complementary scientific techniques with the observations of a skilled art conservator, we were able to prove conclusively that the underlying grounding layer of the painting did not contain titanium or titanium dioxide. Upon examining our results, Ms. Foulke concluded, “The findings of the scientists at the RJ Lee Group, that no titanium was found to be present (in the painting), confirms for me that the work was made before titanium white was introduced to artists as a pigment. The appearance of the painting and the aging of the materials are consistent with other paintings I have studied from the first quarter of the 20th century.” Our industrial forensics approach using both scientific results and visual observations confirmed that the painting was created during the lifetime of the presumed artist.