User:Glass nerd/sandbox

Glass deterioration
While glass is generally thought of as a very stable material, it can and does deteriorate. There are two main types of glass deterioration: weathering and atmospheric deterioration. In both cases the composition of the glass and the chemical and physical properties of the environment, especially the amount of moisture, are the key factors that determine the rate and extent of deterioration.

Weathering occurs during burial.

Glass disease, also known as sick glass, is a degradation process of glass. Glass disease is caused by an inherent fault in the chemical composition of the original glass formula. Usually, inadequate calcium oxide causes the alkalis in the glass to remain water-soluble at a low level. Exposure to higher levels of relative humidity during storage or display causes these alkalis to hydrate and leach out of the glass. Upon a reduction of relative humidity, these hydrated alkalis can then form crystals on the surface. This process causes a complex disintegration of the glass which can be identified through a variety of symptoms, including is a distinctive network of fine cracking, also called crizzling, which can reduce the transparency of the glass or even threaten the integrity of the structure.