Plastering Techniques: Applies coats of plaster to interior walls, ceilings, and partitions of buildings, to produce finished surface, according to blueprints, architect's drawings, or oral instructions, using hand tools and portable power tools. Workers mix plaster to desired consistency. Spreads plaster over lath or masonry base, using trowel, and smooths plaster to attain uniform thickness. Applies scratch, brown, or finish coats of plaster to wood, metal, or board lath successively. Roughens undercoat with scratcher (wire or metal scraper) to provide bond for succeeding coats of plastering. Drywall/ Plastering finishes.