Lath and Plaster
The lath and plaster process consists of tacking thin strips of wood lath over the entire wall or ceiling framing members with approximately 3/8 inch gaps between the strips. Lime or gypsum based putty is then applied in three coats. The first, called the scratch coat is applied about 3/8 inch thick and is also forced between the gaps in the laths forming “keys” that lock into the gaps and ensure a solid bond. The “brown coat comes next. It is also approximately 3/8 inch thick and is troweled into a semi-smooth uniform surface. A final 1/8 inch thick “white coat” is applied which completes the process leaving a uniform, smooth textured surface that is ready to paint.