Catalyst - In fiber reinforce plastics the catalyst is the substance added to the gel coat or resin to initiate the curing process. The catalyst usually oxidizes an accelerator creating free radicals which cause the resin or gel coat to polymerize or cross-link.

Closed-Molding - A molding process using two matched molds. This method of molding reinforced plastic provides a good inside and outside surface. This type of mold tooling is much more expensive than open mold tooling.

Curing - A polymerization process transforming the liquid resin to a solid creating the maximum physical properties attainable from the materials.

Gel Coat - A colored resin used as a surface coat for molded fiberglass products. It provides a cosmetic enhancement and environmental protection for the fiberglass laminate.

Hand Lay-up - Placing reinforcement materials and resin onto a mold by hand. The resin application is frequently accomplished with a spray gun.

Open Molding - An open mold provides a finished and dimensional accurate surface upon which the lay-up can be placed. Gel coat is usually sprayed first on the prepared surface of the mold. The reinforcement materials are applied on top of the gel coat. This form of molding provides on finished side.

Resin - A class of organic products either natural or synthetic in origin, generally having high molecular weight. Most uncured resins used in open molding are liquids. Generally resins are used to surround and hold fibers. When catalyzed, the resin cures going through a polymerization process transforming the liquied resin into a solid. The cured resin and reinforcement creates a composite material with mechanical properties that exceed those of the individual components.

Styrene - An unsaturated hydrocarbon used in plastics. In polyester resin it serves as a solvent and as a co-reactant in the polymerization process that occurs during curing.

Wet-Out - Saturating reinforcing material (glass fiber) with resin. The rate or speed of saturation is a key factor in effective and profitable molding.