Anneal: To prevent or remove
objectionable stresses in glassware by
Binder (Fibrous Glass): Substances
employed to bond or hold the fibers
Blister: An imperfection a relatively
large bubble or gaseous inclusion.
Check: an imperfection; a surface crack
in a glass article.
Chill Mark: A wrinkled surface condition
on glassware, resulting from uneven
contact in the mold prior to forming.
Chip: An imperfection due to breakage of
a small fragment from an otherwise
Cord: An unattenuated glassy inclusion,
possessing optical and other properties
differing from those of the surrounding
Cullet: waste or broken glass, usually
suitable as an addition to raw batch.
Devitrification: Crystallization in
Dice: The more or less cubical fracture
of tempered glass.
Fiber: An individual filament made by
attenuating molten glass. A continuous
filament is a glass fiber of great or
indefinite length. A staple fiber is a
glass fiber or relatively short length
(generally less than 44cm).
Fusion: Joining by heating.
Glass Ceramic: A material melted and
formed as a glass, then converted
largely to a crystalline form by
processes of controlled devitrification.
I.D.: Inside diameter.
Lampworking: Forming glass articles from
tubing and rod by heating in a glass
Lap: (1) An imperfection; a fold in the
surface of a glass article caused by
incorrect flow during forming. (2) A
process used for mating ground surfaces.
Liquidus Temperature: The maximum
temperature at which equilibrium exists
between molten glass and its primary
Mat (Fibrous Glass): A layer of
intertwined fibers bonded with some
resinous material or other adhesive.
O.D.: Outside diameter.
Out-of-Round: Asymmetry in round glass
Sealing: Joining by heating.
Seed: An extremely small gaseous
inclusion in glass.
Softening Point: the temperature at
which a uniform fiber, 0.5 to 1.0mm in
diameter and 22.9 cm in length,
elongates under its own weight at a rate
of 1 mm per minute when the upper 10cm
of its length is heated in a prescribed
furnace at the rate of approximately 5ēC
per minutes. For a glass of density near
2.5, this temperature corresponds to
viscosity of 10 7.6 poises.
Standard Taper: A two part number,
24/40, with 24 being the approximate
diameter in millimeters at the large end
of the taper and 40 the axial length of
taper, also in millimeters.
Stone: An imperfection; crystalline
contamination in glass.
Stria: A cord of low intensity generally
of interest only in optical glass.
Tempered Glass: Glass that has been
rapidly cooled under rigorous control
from near its softening point to
increase its mechanical and stermal
Thermal Endurance: The relative ability
of glassware to withstand thermal shock.
Weathering: Attack of a glass surface by
Working Range: The range of surface
temperature in which glass is formed
into ware in a specific process. The
"upper end: refers to the temperature at
which the glass is ready for working
(generally corresponding to a viscosity
of 10 3 to 10 4 poises), while the
"lower end" refers to the temperature at
which it is sufficiently viscous to hold
its formed shape (generally
corresponding to a viscosity greater
than 10 6 poises). For comparative
purposes, when no specific process is
considered, the working range of glass
is assumed to correspond to a viscosity
range from 10 4 to 10 7.6 poises.
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