An initial layer of a resin and metal filler mix are applied to the surface of the mould then the mould can be back filled with non metal filled resin. Once cured the cast piece is carefully polished with fine wire wool to bring out the finish of the metal. The higher the ratio of metal filler to resin used the higher the quality of the finish. As an approximate guide the minimum ratio would be a 1:1 mix for the metal powders, for every 100g of metal powder to every 100g of resin, depending on casting requirements this could be increased up to 4 parts metal powder to 1 part resin by weight. The examples given are to be used only as a guide and user must always perform small tests to ensure a ratio that suits their requirements. The ratio will also be altered depending on the resin being used.
A more efficient method if is to cover the surface of the mould in the powder, turn over and tap. A thin layer will stick to the surface and the excess will fall off which can be collected and used again. Very gently pour in the resin being careful not to disturb the powder. The resin will soak into the powder leaving a very thin dense layer of metal on the surface of the cast that can then be polished.