Ready Patch Ready Patch For heavy-duty repairs over drywall, plaster, wood, metal and masonry. Sticks to metal. Use to repair dents in metal doors and siding. Dries fast and cures rock hard. Shrink resistant. Can be painted when dry to the touch. Combines the workability of spackl ing paste with the strength of plaster. Covers 13 sq. Ft. Per gallon applied at a thickness of 1/8 inch.