Plastering provides thin layer of mortar on the surface of brick walls, concrete surfaces and composite metal surfaces. It protects the surface from water penetration and other atmospheric influences. Provides durable, uniform and finished surface for the application of paint.
Plaster is a blend of sand and cement with adequate amount of water. The layer of plastering is in two coats . First layer of rough coat is followed by a finish coat. It covers up the undulation and pores in wall surface and makes it aesthetically beautiful, in addition by Plastering we can do decorative works also.
The required quality and strength of plaster is obtained by doing the following steps.
1. Clean the surface
- Do Surface preparation for rendering the required durability of plaster. Thus it creates a satisfactory bond between the plaster and the surface. The surface should be clean and free from loose particles. Dust removed by water or by scrapping tool or by using wire brush.
2. Roughness
- Raking on the brick wall gives roughness to the surface for adhesion. To have good bonding , the surface should be rough. Sprinkling water or plain grout on the surface helps bonding. Hack smooth concrete surface to have good adhesion.
3. Surface unevenness
- To minimize the plaster thickness the surface of plaster have to be free of undulations. Otherwise depending on the surface unevenness, the thickness of plaster will vary.
4. Discontinuity of surfaces
- Discontinuity in plastered surface forms cracks. For instance, change from concrete to brick surface, clay brick to cement blocks . Provide a layer of plastering mesh at junction of discontinuity before plastering which prevents formation of cracks.
5. Curing
- To develop maximum strength and density of the plaster proper curing is necessary. Similarly, Curing shall be done as soon as the plaster has hardened and are not susceptible to damage. The plastered surface however are kept damp for a period of 7 days. Cured by Water sprayed on the plastered surface or by the use of wet gunny bags hanged to the surface.
6. Specification and standards
- Sieve the sand as per specification and grade . The proportion of cement mortar should be as per standards. Above all, the mix of mortar shall be 1:4 for ceiling and 1:6 for walls. Water used in plastering should be of quality suitable for drinking and must be free from chlorides and organic impurities.
7. Check Levels and Undulations
- The minimum thickness of mortar maintained by fixing button marks on plastering surface . In addition, the distance of button marks should be within an aluminium straight edge. All marks on wall are to be in level from ceiling .
- Check for smooth finish using spirit levels for undulations. Cracks and straightness in vertical and horizontal directions after plastering.
- Yellow halogen lights used to check the undulation on surface. Throw light from one side and undulations in the plaster is visible. For instance, it can be rectified immediately while the mortar is still fresh.
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