Historical glasses show a variety of corrosion phenomena, including microcracks and pitting. The formation of a crack pattern in the gel layer and the development of corrosion products on the surface depend mainly on the chemical composition of the glass and on the corrosive agents. The complexity of environmental conditions as well as the unknown history of art objects, however, make it difficult to explain the degradation of historical glass as a function of its environmental parameters. Systematic investigations on the corrosion behaviour of ancient glass have to be carried out as simulation experiments in the laboratory. Degradation phenomena observed on stained glass windows have been simulated on model glass, the composition of which was modified to increase the corrosion sensitivity.
