Concrete plaster wall repair crack#

There are 4 possible types of plaster lath: wood, wire mesh, gypsum board, and masonry like brick or concrete. Instead materials like setting-type joint compound are now used for repairing plaster white coat.

Concrete plaster wall repair crack#

Because plaster of Paris is hard to work with and tends to crack easily, it isn't used much any more. The white coat consists of plaster of Paris and lime mixed together to create a hard, smooth finish when it sets. The brown coat is made up of the same basic ingredients as the scratch coat and it's applied in the same manner but the surface is left smooth to help make the next coat -the white coat- easier to smooth and level. This makes the next coat -the brown coat- adhere better and creates a strong bond between the two.

While the scratch coat is still wet, it's roughed up with a stiff brush to leave scratches in the surface. This mixture is applied over the lath and pushed into the gaps between the wood strips to form a key that locks the two together. The first wet coat -the scratch coat- is a mixture of sand, Portland cement, and some filler material such as horsehair. The wet plaster is made up of three separate components: the scratch coat the brown coat and the putty coat, also called the white coat. With wood-lath plaster there are two basic components: the wood strips that make up the lath and the wet mixtures of plaster that create the hard, smooth wall surface. With this type of plaster, three different types of mud are applied over a lathing material to build up a smooth wall or ceiling finish. This page contains instructions for repairing and restoring old, damaged three-coat plaster.