The potential of attenuated total reflection Fourier transform infrared (ATR-FTIR) imaging for the characterisation of the
chemical components of paint cross sections from old master paintings was investigated. Three cross sections were chosen to
cover a variety of the analytical problems encountered in samples from paintings. The binding medium and degradation products
in a green paint sample from a fifteenth-century Florentine painting were imaged, as well as a thin layer within a cross-section
from a fifteenth-century German painting, and multiple thin surface coatings on a painting of the 1760s by Peter Romney. The
application of chemometric methods for further analysis of the large data set generated for each sample was also explored.
The study demonstrated the advantages of ATR-FTIR imaging, which allowed images to be obtained with high spatial resolution
(ca. 3–4 μm) without the need to microtome the sample. The gain in sensitivity in detecting trace materials and the information
derived from the location of these compounds in the sample was especially valuable, improving interpretation of the FTIR analysis
and extending knowledge of the sample composition beyond that obtainable with other analytical techniques.
Keywords ATR-FTIR imaging spectroscopy - Chemometrics - Paintings - Cross sections