Plaster is a thin layer of mortar applied over the masonry surface and it acts as a damp-proof coat over the brick masonry work. Plastering also provides a finished surface over the masonry that is firm and smooth hence it enhances the appearance of the building. The primary objectives of plastering are to protect the surface from atmospheric influences, to cover the defective workmanship in masonry, to conceal porous materials, and to provide a suitable surface for painting.
Plastering work

Standard Specifications used for the Plastering Work
1. American Standards

ASTM C926 Standard Specification for Application of Portland Cement-Based Plaster

2. New Zealand Standards

NZS 4251-1 (2007): Solid plastering – Cement plasters for walls, ceilings and soffits

3. European Standards

BS EN 998-1 Specification for mortar for masonry – Part 1: Rendering and plastering mortar.

4. Indian Standard (BIS codes)

IS 383 Specification for coarse and fine aggregates for natural sources for concrete.
IS 1542 Specifications for sand for plaster
IS 2645 Specifications for integral cement waterproofing compound
IS 8112 Specification for 43 grade OPC
IS 269 Specification for 33 grade OPC
IS 1489 Specification for Portland Pozzolana Cement

Procedure of Plastering Work
1. Preparation of Surface for Plastering

Keep all the mortar joints of wall rough, so as to give a good bonding to hold plaster.
Roughen the entire wall to be plastered.
Clean all the joints and surfaces of the wall with a wire brush, there should be no oil or grease etc. left on wall surface.
If there exist any cavities or holes on the surface, then fill it in advance with appropriate material.
If the surface is smooth or the wall to be plastered is old one, then rake out the mortar joint to a depth of at least 12 mm to give a better bonding to the plaster.
Wash the mortar joints and entire wall to be plastered, and keep it wet for at least 6 hours before applying cement plaster.
If the projection on the wall surface is more than 12 mm, then knock it off, so as to obtain a uniform surface of wall. This will reduce the consumption of plaster.

2. Groundwork for Plaster

In order to get uniform thickness of plastering throughout the wall surface, first fix dots on the wall. A dot means patch of plaster of size 15 mm * 15 mm and having thickness of about 10 mm.
Dots are fixed on the wall first horizontally and then vertically at a distance of about 2 meters covering the entire wall surface.
Check the verticality of dots, one over the other, by means of plumb-bob.
After fixing dots, the vertical strips of plaster, known as screeds, are formed in between the dots. These screeds serve as the gauges for maintaining even thickness of plastering being applied.