It is a type of treatment made when the glass is cold using the fluorhydric acid which is the only able to natch the glass. It has a decorative effect similar to sandblasting but thinner and intangible.

Satin or acid etching of glass is a permanent chemical process that gives the glass a velvety and soft feel, eliminating transparency, but not light transmission.
Maurice Marinot was one of the most virtuous artists and he used acid to obtain effects that had never been obtained before.

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Glossary