Interlux Interstain Wood Filler Stain Interlux Interstain fills the grain of the wood so that the number of coats of varnish can be reduced and it stains the wood to enhance its natural beauty. Fills wood grain Stains the wood to enhance its beauty A great base for Interlux varnishes Sold in pints Specifications Finish Matte Number of Coats As required Application Method Brush Interlux Brush Thinner Thinner. Interlux Interstain is a thick paste before using. It must be mixed with thinner to the