Volatile organic compoundVOC

A reactive monomer that acts as both diluent and crosslinking agent in unsaturated polyester and vinyl ester resins, copolymerising into the cured network rather than evaporating like a true solvent. Styrene content influences viscosity and shrinkage, and workplace exposure to styrene vapour is subject to occupational limits.

The regulatory framework for the Registration, Evaluation, Authorisation and Restriction of Chemicals, operating as EU REACH and, since Brexit, a parallel UK REACH regime. It governs which substances may be used in products such as resins, hardeners and coatings, and requires suppliers to communicate the presence of substances of very high concern through the supply chain.

A pigmented, resin-rich surface coat applied to the mould face before laminating, which cures to form the smooth, weather-resistant outer surface of a GRP moulding. It protects the underlying laminate from moisture and UV exposure and provides the colour and gloss of the finished part.

A thermosetting resin dissolved in a reactive monomer, usually styrene, that cures by free-radical polymerisation when initiated with an organic peroxide such as MEKP. It is the workhorse matrix for glass-reinforced plastic in boat building, GRP roofing, tanks and vehicle panels, offering low cost and straightforward processing.