Acid etching of glass
Acid etching of glass is a chemical decoration process. The surface is covered with an acid resistant material, often wax, and the design is scratched through this resist. Hydrofluoric acid attacks the exposed glass.
Features
The process can produce matte decoration, lettering or patterns with soft transitions. Acid fumes may also frost a larger surface. Commercial acid etching developed in England during the nineteenth century, but the technique alone does not securely date an object.
Confusions
Acid etching should be distinguished from sandblasting, grinding and natural weathering. Look for even chemical frosting, boundaries formed by the resist and agreement with the rest of the decoration. Hydrofluoric acid is extremely dangerous and the process requires professional safety training.
