Making the mould
The GRP or glass fibre mould process begins with an object known as the pattern or plug.
This is an exact representation of the object to be made. The pattern can be made from a variety of different materials.
After the pattern has been formed, it is sprayed with a mould release agent. The release agent will allow the mould to be separated from the pattern once it is finished. The mould release agent is a special wax.
Once the pattern has its release agent applied, gel coat is applied with a roller, brush or specially-designed spray gun. The gel coat is pigmented resin, and gives the mould surface a harder, more durable finish.
Once the release agent and gel coat are applied, layers of glass fibre and resin are laid-up onto the surface. The glass fibre used will typically be identical to that which will be used in the final product.
In the laying-up process, a layer of fiberglass mat is applied, and resin is applied over it. A special roller is then used to remove air bubbles. Air bubbles, if left in the curing resin, would significantly reduce the strength of the finished mould. The glass fibre lay-up process is also used to produce moulds.
Once the final layers of fiberglass are applied to the mould, the resin is allowed to set up and cure. Wedges are then driven between the pattern and the mould in order to separate the two.
Making the product
The component-making process involves building up a component on the glass fibre mould. The mould is a negative image of the component to be made, so the glass fibre will be applied inside the mould, rather than around it.
As in the mould-making process, release agent is first applied to the mould. A coloured gel coat is then applied. Layers of glass fibre are then applied, using the same procedure as before. Once completed and cured, the component is separated from the mould using wedges, compressed air or both.