Evidence concerning oxidation as a surface reaction in Baltic amber

The aim of this study was to provide evidence about oxidation as a surface reaction during degradation of Baltic amber. A clear understanding of the amber–oxygen interaction modalities is essential to develop conservation techniques for museum collections of amber objects. Pellet-shaped samples, obtained from pressed amber powder, were subjected to accelerated thermal ageing. Cross-sections of the pellets were analyzed by infrared micro-spectroscopy, in order to identify and quantify changes in chemical properties. The experimental results showed strong oxidation exclusively at the exterior part of cross-sections from samples subjected to long-term thermal ageing, confirming that oxidation of Baltic amber starts from the surface.