Understanding the material composition of painting layers is important for studying
their degradation processes and for planning appropriate conservation and restoration
treatments. Among the commonly used analytical methods is Fourier-transform infrared
(FTIR) spectroscopy, which enables the identification of organic and inorganic
components in painting layers. Reflectance FTIR spectroscopy represents a non-
invasive method for analysing the surface of artworks; however, the interpretation of
reflectance spectra is often more challenging than that of transmission spectra.
The aim of this thesis was to analyse model samples of Baroque painting layers using
reflectance FTIR spectroscopy and to evaluate the changes occurring after accelerated
degradation. To facilitate the interpretation of the reflectance spectra, selected reference
materials and paint layers were also analysed by transmission FTIR spectroscopy. The
analysed samples contained the pigments lead white and cinnabar in combination with
linseed oil or lean egg yolk, as well as protective coatings based on egg white and
dammar triterpenoid resin.
The results showed that transmission spectra provide valuable information for the
interpretation of reflectance spectra. Characteristic absorption bands of the individual
pigments, binding media, and protective coatings were identified in the analysed
samples. Comparison of the reference and accelerated degraded samples revealed
changes occurring mainly in the organic materials.
|
