Talc Filler is ideal as a general purpose lightweight filler for resin. It is a very fine and pure white in colour. Also commonly known as 'french chalk'.
It may be added to polyester and epoxy resin to rapidly thicken it, by adding even a small amount there is significant increase in the resin viscosity. This means you can thicken resin to assist application to vertical surfaces and when laminating undercuts.
Talc (french chalk) is also an excellent dry lubricant for use on plastics and rubbers. It can also be used to dust moulds when casting pewter or white metals.