A non-stick coating applied to the inside of a mould so that the gel coat of a moulding (for example, a hull) will not stick to it. An owner is not normally concerned, but carelessness in preparing the mould may result in a need for force to extract the moulding, with the loss of some areas of gel coat. These scars must then be patched in, and if detectable may be an indication of the working standards of the builder.