Engraving glass with a small grinding wheel produces a matt surface, as does etching it with hydrofluoric acid, and sand-blasting. If a shiny surface is desired, the glass can be either polished by hand when cold, or returned to the kiln to melt away surface marks. The texture of ice glass is made by plunging the glass bubble attached to the blowpipe into cold water, then reheating and blowing it. Accidently achieved frosted texturing is caused by crizzling, a glass sickness in which the structure of glass is gradually destroyed by moisture in the atmosphere. An imbalance of ingredients in the batch, particularly an excess of alkali or a deficiency of stabiliser, makes glass prone to crizzling.
Opalescent glass is translucent and white with a greyish or bluish tint.
It is made cloudy and semi-opaque by adding materials such as bone ash to the batch. Mirrors are made by adding a backing of tin, mercury or an amalgam of metals on to the glass.