In-mould gel-coating of polymer composites: a review

Fibre-reinforced polymer matrix composites find use in most transport applications, chemical plant, renewable energy systems, pipelines and a variety of other industries. These applications often require a surface finish for cosmetic and/or durability reasons. The coating is usually polyester or vinyl-ester gel-coat painted or sprayed onto the mould tool before the structural composite is laminated. Alternatively a (typically polyurea) coating may be sprayed onto the surface of the cured composite part. The process may emit vapours (normally volatile organic compounds, VOC) into the workplace and the environment. This review paper will consider the potential for in-mould gel-coating as a route to improved workplace conditions and reduced environmental impact. It will also address measurement of quality by adhesion, surface characterisation, and long-term durability. Customer satisfaction is the key driver for gel-coated products.