Friday, January 8, 2010
Etching refers to the technique of creating art on the surface of glass by applying acidic, caustic, or abrasive substances. Traditionally this was done after the glass was blown or cast.
In the 1920s a new mould-etch process was invented, in which art was etched directly into the mould, so that each cast piece emerged from the mould with the image already on the surface of the glass. This reduced manufacturing costs and, combined with a wider use of colored glass, led to cheap glassware in the 1930s, which later became known as Depression glass. As the types of acids used in this process are extremely hazardous, abrasive methods have gained popularity.
Typically, "glass etching cream" available from art supply stores consists of fluoride compounds, such as sodium fluoride and hydrogen fluoride. The fluoridation of the glass (which is a network covalent solid of silicon dioxide molecules) causes the characteristic rough, opaque qualities of frosted glass.