FTIR analysis of historic documents degraded by iron-gall inks

The corrosion of ancient paper documents induced by iron gall inks has been analysed by means of non-destructive Fourier Transform Infrared Spectroscopy (FTIR) in order to identify the organic components of the degradation. In this first step of the research, the FTIR spectra have been classified on the basis of their absorbance in the 1730-1600, 1360-1250 and 890-702 cm-1 regions (mainly due to oxalates) and the 1200-900 cm-1 region (due to sulphates). At least 5 classes of degraded inks have been identified on the basis of some minor spectral features. This preliminary classification will be useful for the further steps of the research, aimed to identify the main products of degradation of iron- gall inks and to simulate their degradation with accelerated ageing techniques for a better set up of conservation and restoration procedures.