Generally metal powders are added at user discretion, every project is different and can be added to each specific application to give the desired metal effect. 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.
We would always advise were possible to dust the mould with metal powder first before backing with a resin-powder mix to give a deep metallic finish. Different powders can be mixed together but make sure the powders are premixed before adding to the resin.