A gel coat is the first layer of resin applied to the prepared mould, it forms the finish of one of the surface laminations, providing protection against chemicals, weathering, moisture or any aggression from the environment. Chemically, gels coats are thermosetting resins with pigments and additives in suspension which allow its application to the mould surface, even in vertical walls without sagging. Generally they have greater abrasion resistance and corrosion resistance, as well to the UV radiation and to temperature changes than their base resins.
They shall be applied with a consumption of 600 g/m2 for parts and a maximum of 1 kg/m2 for moulds.
What properties does a gel coat provide to fiberglass plastic reinforcements?
Quality and color stability. Weatherability. Water resistance (no bubbles) Heat resistance. Abrasion resistance. Absence of surface porosity. High brightness, permanent in time. Resistance to chemicals.
Types of polyester gelcoats
Orthophthalic polyester: industrial parts with good mechanical and light stability properties. It is used for general purposes that do not require high especific properties (weatherability, hydrolysis, water, food or chemical resistance).
Isophthalic polyester: better performance in open air, in marine environment, to high temperatures and to solvents. Mainly used for nautical and health applications.