Glass disease, also referred to as sick glass or  glass illness, is a degradation process of glass that can result in weeping, crizzling, spalling, cracking and fragmentation.
Glass disease is caused by an inherent instability in the chemical composition of the original glass formula. 
Properties of a particular glass will vary with the type and proportions of silica, alkali and alkaline earth in its composition.
Once damage has occurred it is irreversible, but decay processes can be slowed by climate control to regulate surrounding temperature, humidity, and air flow.