Glass etching, or “French embossing,” is a popular technique developed during the mid-1800s that is still widely used in both residential and commercial spaces today. Glass etching comprises the techniques of creating art on the surface of glass by applying acidic, caustic, or abrasive substances. Traditionally this is done after the glass is blown or cast, although mold-etching has replaced some forms of surface etching. The removal of minute amounts of glass causes the characteristic rough surface and translucent quality of frosted glass.
Acid etching is done using hexafluorosilicic acid (H2SiF6) which, when anhydrous, is colourless. The acid is prepared by dissolving silica in a mixture of hydroelectric acid (hydrochloric acid), quartz powder, calcium fluoride, and concentrated sulfuric acid derived after heating.
Glass etching cream is used by hobbyists as it is generally easier to use than acid. Available from art supply stores, it consists of fluoride compounds, such as hydrogen fluoride and sodium fluoride (which are still very dangerous). As the types of acids used in this process are extremely hazardous (see hydrofluoric acid for safety), abrasive methods have gained popularity.
Abrasive blasting (“sandblasting”) is another common technique for creating patterns in glassware, creating a “frosted” look to the glass. It is often used commercially. High-pressure air mixed with an abrasive material cuts away at the glass surface to create the desired effect. The longer the stream of air and abrasive material are focused in one spot, the deeper the cut.