Crizzling (chemical deterioration of glass)

Crizzling is chemical deterioration in unstable glass, characterised by a network of fine surface cracks. The Corning Museum of Glass links it to an imbalance in the glass composition and exposure to atmospheric moisture. Early fissures may be difficult to see; more severe deterioration can produce cloudiness and surface loss.

The Canadian Conservation Institute distinguishes these fissures from weeping, in which liquid droplets develop on the surface. Both can indicate unstable glass. Cloudiness alone does not establish a diagnosis. Examine the object before treating dirt, mechanical scratches and chemical deterioration as the same phenomenon.

For purchase and cataloguing, photograph the surface in suitable light and describe visible changes precisely. Affected glass should not be presented as undamaged or as merely needing ordinary cleaning. Consult a conservator about intrusive cleaning or repair. The term does not establish a particular age, authenticity or glassworks.

Sources: Corning Museum of Glass: Crizzling; Canadian Conservation Institute: ustabilt glass.