Beadmaker. Paris, France.
Courtesy the Rakow Research Library, Corning
Museum of Glass
Glass made from silica (70-80%) and boric
oxide (7-13%) with trace amounts of the alkalis (sodium and
potassium oxides) and aluminum oxide. This type of glass is
resistant to thermal shock (it doesn’t break when changing
temperature quickly) and has a low expansion rate. It has been used
for technical glass such as lighting, laboratory apparatus,
cookware (Pyrex) as well as for artistic applications.
-- adapted from the
British Glass Manufacturers' Confederation; "About Glass"
Lampwork (a.k.a. Flamework,
“The technique of forming objects from rods
and tubes of glass that, when heated in a flame, become soft and can
be manipulated into the desired shape. Formerly, the source of the
flame was an oil or paraffin lamp used in conjunction with
foot-powered bellows; today, gas-fueled torches are used.”
The Corning Museum of
Glass online "Glass Glossary"
Annealing (of glass)
Gradually cooling a finished piece of glass at
a controlled rate, in an annealing oven or lehr, to reduce internal
strain. Without annealing, as a piece of glass cools to room
temperature, it contracts and, due to low thermal conductivity, does
not cool uniformly. The surfaces cool more rapidly and shrink more
than the center, producing excessive strain in the glass, and
increasing the risk of breakage.
For more information, see: