GRP stands for Glassfibre Reinforced Plastic - plastic resin (usually polyester) reinforced with glassfibre mat or fabric. Polyester resin is a treacly liquid which, when activated by a suitable catalyst (hardener), sets to a hard, rigid plastic. As a liquid, it naturally adopts the shape of its container- hence it can be painted into a mould, and, once cured, will reproduce the shape of the mould. The hardened plastic is fairly brittle so glassfibre materials are added to give considerably increased strength (just as steel rods are used in reinforced concrete). The plastic cures at room temperature (unlike polythenes, polypropylenes and other materials which need heat and pressure) and it can be easily used in a small workshop (and. for some projects, even in the home), without any need for specialised equipment.
What is GRP?
GRP, the combination of polyester resin and glassfibre, is a remarkably versatile material - strong, durable, weatherproof, waterproof, non-rusting, easily moulded to virtually any shape, highly adhesive to a wide range of materials, and capable of making structures of almost any size.