Many methods exist to analyze pigments and binders on paintings. They sometimes require the removal of material from the artwork.
Invasive methods
The methods with sampling consist in taking a microscopic part of the pictorial material in order to analyze it. The collected pictorial material is examined under an optical microscope in order to study the stratigraphy of one of the paint layers. To do this, the paint is embedded in a resin and polished in order to observe the different layers which constitute the sample (preparation layer, colored undercoat…). We can thus study the pigment grains and the alterations of the paint layer.
The analysis of the pigments and binders of an artwork is also used to give information by cross-checking on a probable dating by comparing the analyzed pigments with the dates of manufacture of the colors used.
The analysis of the pigments in the stratigraphic section allows a better understanding of the structure of the painting. It reveals overpainting, accidents and cracks, and sometimes even allows the identification of certain pigments.
Non-invasive methods
X-ray fluorescence is a basic analysis that is non-contact and non-taking. X-rays are projected onto the paint layer making each element react in characteristic way.
X-ray fluorescence gives information on the entire thickness of the paint (and not just the superficial layers), so it does not give precise stratigraphic information.