Etching refers to the technique of creating art on the surface of
glass by applying acidic, caustic, or
frosted glass.
abrasive substances.
Traditionally this is done after the glass is blown or cast, although
mold-etching has replaced some forms of surface etching. The removal of
minute amounts of glass causes the characteristic rough surface and
translucent quality of
Techniques
Various techniques are used to achieve an etched surface in glass,
whether for artistic effect, or simply to create a translucent surface.
Acid etching is done using
hexafluorosilicic acid (H
2SiF
6) which, when
anhydrous,
is colourless. The acid is prepared by dissolving silica in a mixture
of hydrofluoric acid, quartz powder, calcium fluoride, and concentrated
sulfuric acid derived after heating.
Glass etching cream is used by hobbyists as it is generally easier to use than acid. Available from art supply stores, it consists of
fluoride compounds, such as
hydrogen fluoride and
sodium fluoride
(which are still very dangerous). As the types of acids used in this
process are extremely hazardous, abrasive methods have gained
popularity.
Abrasive blasting
("sandblasting") is another common technique for creating patterns in
glassware, creating a "frosted" look to the glass. It is often used
commercially. High pressure air mixed with an abrasive material cuts
away at the glass surface to create the desired effect. The longer the
stream of air and abrasive material are focused in one spot, the deeper
the cut.
Leptat glass is glass that has been etched using a patented
acid process. Leptat takes its name from the Czech word meaning "to
etch", because the technique was inspired by a Czechoslovakian glass
exhibit viewed at a past World’s Fair in Osaka, Japan, and patented in
the United States by Bernard E. Gruenke, Jr.
[1] of the
Conrad Schmitt Studios.
Abstract, figural, contemporary, and traditional designs have been
executed in Leptat glass. A secondary design or pattern is sometimes
etched more lightly into the negative areas, for further interest. Gold
leaf or colored enamels also can be inlaid to highlight the designs. The
Leptat technique allows the glass to reflect light from many surfaces,
like a jewel-cut gem.
Mold etching In the 1920s a mold-etch process was invented, in which art was etched directly into the
mold,
so that each cast piece emerged from the mold with the texture already
on the surface of the glass. This reduced manufacturing costs and,
combined with a wider use of colored glass, led to cheap glassware in
the 1930s, which later became known as
Depression glass.
Frost Etching is the process in which vinyl window material is
cut to produce a pattern and then applied to a window to give a frosted
patterned effect.
From
https://en.wikipedia.org/wiki/Glass_etching
