Engraving is a process of decorating cold glass by removing material.there are several modes of engraving: direct engraving, the wheel and the tip or indirect, acid and sandblasting. Acid etching consists of immersing the glass in a bath of hydrofluoric acid. The decoration is created by the bite of the acid while the parts known as "in reserve", previously coated with a protective bitumen varnish, escape corrosion and remain transparent.
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