aspersorium

Places of worship in private homes were often equipped with wall-mounted fonts, as well as small glass buckets, for holy water. The buckets were sometimes suspended from a metal hook on the wall of a bedroom or study. This bucket was made of glass with a surface that resembles cracked ice. There are two ways to achieve this effect. The first method calls for a parison of hot glass to be plunged into cold water and withdrawn quickly. The thermal shock creates fissures in the surface, and these impart a frosted appearance after the parison has been reheated to allow the forming process to continue. In the second method, chips of colorless glass, picked up on a gather (a gob of molten glass) as it is rolled across a flat surface, fuse to the bubble as it is reheated. Ice glass was first made in 16th-century Venice, where it was often blown into a mold and decorated with colored trails.