Fourier transform infrared spectroscopy (FTIR) is an analytical technique that can identify traditional paint media, such as oil, alkyd resin, egg tempera, natural and synthetic resins, proteins and waxes, by characteristic absorption of infrared radiation. FTIR can also be used for the identification of both organic and inorganic materials (often pigments and dyes) within a sample.
FTIR requires sample removal, however it is non-destructive to the sample. While the technique can give a good indication of the binder used and materials present, interference by pigments can make interpretation of the results difficult. GC-MS is often used to confirm or better clarify the results obtained by FTIR.
The results are interpreted and presented in a report, with the FTIR spectra included (example below).
Discuss the possibility of undertaking FTIR with a conservator.