Beeswax-rosin mixtures in historical wet collection sealants: Qualitative analysis of their composition by DSC and ATR-FTIR spectroscopy

Abstract

Wet collections sealants are historical materials that are essential for a sustainable preservation of specimens in fluid. Yet little is known about their composition, apart what can be found in technical records. Few scientific studies are dedicated to the identification of these materials that often correspond to complex mixtures. This work aims at facilitating the characterization of beeswax-rosin mixtures used for sealing wet collections. It explores the possibilities to quantify the proportions of beeswax-rosin mixtures by Differential Scanning Calorimetry (DSC) and Attenuated Total Reflectance Fourier Transformed mid-Infrared Spectroscopy (ATR-FTIR), two easy-to-run methodologies that require small samples. First these techniques were tested on model beeswax-rosin mixtures and appeared complementary. Then they were implemented on historical sealants and cross-checked with Pyrolysis Gaz Chromatography Mass Spectroscopy (Py-GC/MS) measurements, giving promising results. The impact, on the results, of ageing or of possible addition of third-party fatty materials such as animal fat or vegetal oil is also discussed.