The application of FTIR-microscopy to the analysis of paint binders in easel paintings

The basic principles of Fourier transform infrared (FTIR) spectrometry are outlined, with particular reference to the use of the FTIR microscope. In practice, background subtraction and first and multiple derivatives of the spectra are used to aid interpretation. A sample preparation technique which involves pressing the paint sample into a block with powdered silver chloride, then cutting or microtoming the block while worked in a subdued light. The sample left in the block can be removed cleanly for further analysis. Examples of oil paint over an egg tempera underpaint in a Van der Weyden panel, glue from a tuchlein by Dieric Bouts, and an interesting use of glazing by Garofalo are given, with emphasis on spectral interpretation and the usefulness of FTIR microscopy when combined with gas chromatography. -- AATA