Glasswork - the Scientia Review

Water is the most primary mechanism of decomposition.
It forms a number of acidic solutions with ease and without special
conditions. The resultant mild acids withdraw alkali from the silica
structure of the glass. The removal of this substance renders the core
material weak, but also harms the surface; at the surface, alkaline
compounds actually retain water and catalyze the degradation
process. When glass reaches this state, the surface often feels
slippery, and this effect is referred to as weeping. The alkali removal
causes visible cracks to develop which account for a cloudy
appearance. Heightened alkali withdrawal results in flaking.
Extreme thermal fluctuation also poses a threat by creating forces
between the glaze and base of a glass, often separating these adjacent
layers.
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