NON INVASIVE TECHNIQUES FOR THE INVESTIGATION OF FOXING STAINS ON GRAPHIC ART MATERIAL

The yellow/brown stains of circular or irregular shape known as foxing spots have been fully described in conservation literature but still, this phenomenon do not find any scientific agreement since many hypot heses have been raised concerning their origin but we deplore a lack o f chemical and experimental evidences. In this work we have used two n on invasive techniques for the chemical identification of foxing stain s in order to define objective keys for a taxonomy of these stains. Fl uorescence gives poor chemical information but if fluorogeniccompounds would be the precursors of the brown end products, the quantitative m easurement of fluorescence would be of major interest for preventive c onservation. FTIR spectroscopy provides more chemical information and as such, FTIR is a very relevant tool for a taxonomy of foxing stains. Since many chemical bonds may overlap in the same region, the interpr etation of FTIR spectra are discussed.