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Gel Coat

See also: Categories: Fiberglass Pools, Terminology


Gel Coat (gelcoat) refers to a material used to provide a high-quality finish on the visible surface of a fiberglass composite pool. When sufficiently cured and removed from the mold, presents the gelcoated surface.


The most common gelcoats are based on epoxy or unsaturated polyester resins. Gelcoats are modified resins which are applied to moulds in the liquid state. They are cured to form crosslinked polymers and are subsequently backed with composite polymer matrices, often mixtures of polyester resin and fiberglass or epoxy resin with glass.

Gelcoat color

Polyester gel coats come in either white or clear form, which is pigmented to a variety of colors. Clear gel coats reproduce colors very accurately, while white gel coats yield pastel colors. Epoxy surface coat is white in color, and can also be pigmented

Typical application

Typical application of the gelcoat is 0.5 mm to 0.8 mm (0.02 in to 0.03 in) thick.

Molds application

Gelcoats are designed to be durable, providing resistance to ultraviolet degradation and hydrolysis.

Specialized gelcoats can be used to manufacture the moulds which in turn are used to manufacture pools. These require very high levels of durability to overcome the mechanical and thermal stresses encountered during the curing and demoulding processes. In addition to any pigment a gelcoat will, if necessary, contain a thixotropic additive to assist its tenacity to vertical portions of the mould whilst it cures.

Most common gelcoats

Most commonly encountered gelcoats are unsaturated polyesters or epoxies.

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