Pore-O-Pac Natural Grain Filler, Quart - Solvent Base - New Formula. Compatable With Almost All Sealers & Topcoats. Our Natural Grain Filler is used for filling open grained woods. A fine blended mixture of silica, pigments, and a suitable vehicle, it provides a smooth, glass-like surface for subsequent finishing coats. Pore-O-Pac should be used over a wash coat of sealer. A 24-hour dry time is necessary before topcoating. A ratio of 4 parts filler to 1 part of reducer is recommended. The filler uses silica, pigments and a suitable vehicle to provide a smooth, glass-like surface for following finishing coats. Reduced VOCs allow it to pass current requirements in all 50 states.