GEL
A semisolid system consisting of a network of solid aggregates in which liquid is held; the initial jell-like solid phase that develops during the formation of a resin from a liquid.

GEL COAT
A resin applied to the surface of a mold and gelled prior to lay-up. (The gel coat becomes an integral part of the finished laminate, and is usually used to improve surface appearance and protect the laminate from the environment.

GEL POINT
The stage at which a liquid begins to exhibit pseudoelastic properties. (This stage may be conveniently observed from the inflection point on a viscosity-time plot). Also, 'gel time.'

GELATION
The formation of a gel.

GFRP
Glass fiber-reinforced plastic, polymer or polyester.

GELATION TIME
That interval of time, in connection with the use of synthetic thermosetting resins, extending from the introduction of a catalyst into a liquid adhesive system until the interval of gel formation

GLASS
An inorganic product of fusion which has cooled to a rigid condition without crystallizing.

GLASS CLOTH
Conventionally-woven glass fiber material (see Scrim).

GLASS FIBERS
A fiber spun from an inorganic product of fusion which has cooled to a rigid condition without crystallizing.

GLASS/RESIN RATIO
The amount of glass by weight compared to the amount of resin by weight in a finished laminate or molding.

GLASS RICH
An area of molded part that has an overabundance of glass reinforcement. The reinforcement may appear dry and unwet with the resin.

GLASS TRANSITION
The reversible change in an amorphous polymer between a viscous or rubbery condition and a hard, relatively brittle one.

GLASS-TRANSITION TEMPERATURE (Tg)
The approximate temperature at which increased molecular mobility results in significant changes in properties of a cured resin. The measured value of Tg can vary, depending on the test method.

GLINT
A visual defect in a fiberglass reinforced cured organic (usually corrosion resistant resin) panel. The defect appears as many small visible unwet or foreign substances - a salt and pepper effect. The defect is not visible before cure but appears at exotherm of the panel.

GRAPHITE FIBERS
See Carbon Fiber.

GRAPHITIZATION
The process of pyrolization at very high temperatures (as high as 5400(F) that converts carbon to its crystalline allotropic form.

GRP
Glass-reinforced plastic, polymer, polyester. this derivation is commonly used in Europe.

GUIDE PIN
A pin, which guides mold halves into alignment on closing.

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Glossary Section (G) Last Updated: 4/27/99 10:18 AM

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