How is hydrofluoric acid used to etch and frost glass?

Hydrofluoric acid is an aqueous solution of hydrogen fluoride that is highly effective at etching and frosting glass because it chemically attacks silica and silicates, which are primary components of most glass.12

The process of etched glass involves using the acid's corrosive properties to cut designs into the surface. A common method involves coating the glass with a protective layer, such as beeswax or paraffin, and tracing a pattern through the wax with a needle. When the glass is dipped into the acid, it etches only the exposed areas.3

The final texture of the glass—whether it appears frosted and rough or satiny and smooth—depends on the specific composition of the glass and the duration of its exposure to the acid. Industrially, etching is often performed using a solution of 6–30 percent hydrofluoric acid combined with a small amount of sulfuric acid, though this practice is generally discouraged due to significant safety risks.34