Characterisation and deterioration of mineral papers

Mineral paper, also known as rich mineral paper, is a paper-like material manufactured from calcium carbonate with a small amount of high-density polyethylene (HDPE), instead of traditional cellulose-based fibres. For environmental reasons, mineral paper was designed to degrade when exposed to sunlight. It was the aim of this study to address the research gap in conservation literature describing the properties and degradation patterns of mineral paper. Three mineral paper samples were characterised using visual examination techniques and analysed using Fourier transform infrared spectroscopy with attenuated total reflectance (ATR-FTIR) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). Calcium carbonate, talc, kaolin, high-density polyethylene and an unknown trace material(s) were identified in these mineral papers. Under accelerated ageing conditions, the mineral paper samples consistently demonstrated a higher rate of chemical and physical degradation compared to a cellulose paper standard when exposed to visible light and ultraviolet radiation. Through this study, a greater understanding was obtained of mineral paper composition, its ageing trajectory, and its response to environmental factors. Further research is required to identify the unknown trace element(s) and whether photo-sensitive additives are present. These results should help to inform the identification, storage, display and treatment of mineral paper-based collections.