Structo-lite Basecoat Plaster Mill-mixed perlite-aggregate gypsum plaster provides a plastic working material that will conform to various designs and help achieve durability in walls and ceilings. Can be applied by hand or machine methods, on gypsum or metal lath, clay tile, concreteor cinder blocks and other approved bases. Mixes with water at the jobsite. Meets ASTM C28. Approximate coverage depends on what plaster is applied over base: Gypsum Lath 140 sq. ft., Metal Lath 89 sq. ft. and Unit Masonry 109 sq. ft.