CIRAM is a laboratory where chemists, physicists and archaeologists work together to meet specific authentication requirements by taking a scientific look at materials. Find out more about the methods we use to meet your requirements.
A global approach to the chemical analysis of paintings
The scientific approach to materials is by definition objective. The dedicated dating method for painted works is Carbon 14, which will date the work's support - canvas, paper, wood, cardboard, etc. For the study of painted works, several types of imaging - natural light, grazing light, ultraviolet (UV) light or infrared (IR) reflectography - complement conventional dating techniques. Finally, historical knowledge of pigment manufacturing techniques provides chronological data.
Thanks to a global approach, CIRAM laboratories can offer results and a precise interpretation of your works of art.
Chemical analysis of pigments
Chemical analysis of the pigments provides important chronological information that complements the dating of the support. This study has been facilitated by the discovery of numerous synthetic pigments in the 19th and 20th centuries. For example, the discovery of lithopone white (barium sulfate and zinc sulfide) in 1870 and phthalocyanine green in the 1930s. The use of chromium oxide as a green pigment from 1840 onwards, for example, or the manufacture of titanium white (titanium oxide), which began in the 1920s.
However, these investigations also have their limitations: natural pigments don't provide any real chronological information, as in the case of ochre, which was used for the Lascaux cave paintings and is still widely marketed today.
Pigment analysis methods
The pigment analysis techniques used by CIRAM laboratories are :
- Light microscopy ;
- Scanning electron microscopy (SEM-EDX);
- Elemental analysis by energy dispersion ;
- Infrared spectrometry (IRTF) ;
- Raman spectrometry ;
- Gas chromatography (GC-MS).
These different techniques can be used to identify the components of a paint: pigments (organic and inorganic), binders and mineral fillers.
Some examples of table analysis
One example is the study of a painting attributed to an illustrious painter of the late 19th century, which was carried out in two stages. Carbon-14 dating of the support gave a date compatible with the painter's activity, and pigment analysis led to a similar conclusion, since the pigments detected were known in the 19th century and had been found in other works by this artist. Among the pigments detected were vermilion red, copper arsenate green, zinc white and ochre.
On the contrary, analysis of a work dated 1920 revealed it to be a fake. The presence of rutile titanium white, manufactured from the late 1940s onwards, was in fact a formal indication of modernity.
Finally, the analysis of a 15th-century illuminated parchment proved more complex, as carbon-14 dating had confirmed the age of the support, but the pigments turned out to be modern (lithopone, titanium white, ultramarine blue, cadmium red...). In reality, it was an "intelligent copy" made on old paper. It is therefore essential to combine dating and analysis techniques to detect forgeries.
Pigment analysis, an essential step in authenticating a work of art
Material analysis is still little-known in the field of scientific authentication of art objects, as it does not provide direct chronological indicators, like carbon-14 dating, for example. Yet the chemical analysis of pigments in a painting remains an essential step in the process of authentication and attribution of pictorial works.
CIRAM laboratories deliver precise results and discuss analyses, interpretations and hypotheses with you to provide a comprehensive study of works of art.
