This process for the decoration of glass involves the application of hydrofluoric acid to the glass surface. Hydrofluoric acid vapours or baths of hydrofluoric acid salts may be used to give glass a matt, frosted appearance (similar to that obtained by surface sandblasting), as found in lighting glass.
Acid etching is a common method of decorating glass and it is similar to sandblasting when it comes to function, but acid-etched glass has more distinctive, uniformly smooth and satin-like appearance.
Glass designs can be produced by coating the glass with wax and then inscribing the desired pattern through the wax layer or by coating the glass with adhesive vinyl stencil with the design cut. When applied, the acid will corrode the glass but not attack the wax or vinyl-covered areas.
Double etching is a decorative technique by which a part of design is etched on glass (e.g. the background) and then an added design is produced by a second dipping in acid while the parts of first design are covered, creating two depths of etching.