Plaster Coats Application

First coat (or rough course of plaster or rendering coat): It is usual for the average thickness of the first coat of plaster to be 12 mm on brick or ashlar masonry and 20 mm on rubble masonry, with a higher thickness on rubble masonry. due to the roughness of its surface and the need to provide a mortar cover of at least 6 mm to the rubble. The first coat of plaster (rendering coat) is usually applied between the screeds described above, striking the wall surface. It is then repeatedly sprinkled with plenty of water and thoroughly rubbed with floats.
If a second coat, called a floating coat, is to be applied, the surface of the first coat is left exposed to air for 2 days to set but dry. After this period, the surface of the first coat is cleaned of any dust or loose particles, sprinkled with water and thoroughly beaten with thin strips of bamboo or cane. The surface of the first coat is kept wet until the second coat is applied.

Second coat or floating coat: After preparing the surface of the first coat as mentioned above, the second coat is applied. The second coat is spread evenly along the trowels. It is pressed and rubbed with a straight edge of wood to achieve the desired surface. Finally the plastered surface is finished by sprinkling some water and rubbing it with floats. The thickness of the second coat is usually between 6 and 9 mm.
Third coat or last coat or finishing coat: This coat is applied after 5 days of second coat. This coat consists of white or greasy lime cream (called nero or plaster putty) and fine white sand in the ratio of 1:2 placed in a straight plane to a thickness of 3 mm and A straight edge is rubbed. The surface is thoroughly rubbed with a wooden float and then finally finished with a trowel to achieve the desired level. A polishing stone is used to achieve a finely polished surface.