Quick-set formulation sets in 30 to 40 minutes. Mixes smoothly and easily with lime to produce smooth-trowel and sand-float finishes for normal interior walls and ceilings. Produces hard, crack, and abrasion-resistant surfaces. Unaggregated for use over sanded basecoats. A smooth trowel finish should not be used over lightweight aggregate gypsum basecoat applied over metal lath (a sand float finish is recommended for this application). Where the gypsum basecoat is Structo-Lite brand basecoat or contains lightweight aggregate (perlite or vermiculite) over any plaster base except metal lath, and when a smooth trowel finish is used, the finish coat should be Red Top gauging plaster and lime with the addition of 1/2 cu. ft. of perlite, or 50 lb. of No. 1 white silica sand per 100 lb. of gauging plaster or quality (mill-aggregated) gauging plaster. Gypsum-based finishes should not be used directly over a Portland cement basecoat or over concrete block, or other masonry surfaces. Complies with ASTM C28. Color: Gray to white, depending on gypsum rock source. 50 lb. bag.