Remedial insight on ageing of glass through the study of ancient man‐made artefacts

Abstract

Ancient man‐made glass artefacts provide vital information about the physical and chemical processes occurring over the long‐term period of weathering conditions. Despite the obvious complications associated with purity, non‐optimal conditions of synthesis and unknown thermal prehistory, the studies are important in the context of surface chemical degradation and structural relaxation theories. The soda‐lime‐silica glass from the sixth‐century bce period of Eastern Europe are studied in this paper by X‐ray photoelectron spectroscopy, differential scanning calorimetry and electron microscopy techniques. The dense, amorphous, about 43 μm‐thick SiO2 layer was detected on the surface of all artefacts; it formed a sharp boundary with the rest of the bulk. Thermal studies show that the ancient soda‐lime‐silica glass did not lose much enthalpy during about 2600 years of natural storage. The results suggest important modifications to a general glass corrosion theory and favour the existence of a terminal temperature for glass relaxation, below which the enthalpy of a macrosystem remains stable. Although the applied methods are rarely used in archaeology, the developed approach allows the value of recovered glass artefacts to be expanded beyond just their cultural or historical significance.