Z Spar S-94 Clear Acrylic Sealer is designed for sealing open grain woods such as mahogany before using filler stains. It is also useful for sealing porous soft woods such as plywood before Z-Spar Undercoat is applied. S-94 seals the grain of the wood to allow light sanding of wood fuzz in a few minutes and promotes uniform penetration of filler stain.