The defects in the plasterwork can be caused due to several reasons. The bricks, mortar and concrete have some amounts of voids themselves. Moisture movement that is causing by drying process of moisture inside the bricks, mortar and concrete during the initial setting out or due to absorption of moisture from environment and expand is main reason for the crack development. Quality of bricks used, workmanship of brickwork or plastering work, quality of mortar mix used, water containing salt used for mortar mixture and dry condition of the plaster surface are some other reasons for the defects in the plastering.
Proper proportioning and mixing of contents and good workmanship (avoid excess troweling) is important to prevent the surface from cracking.
Crazing and Map cracking, De bonding, Lack of hardness, Grinning, Expansion, Popping and Blistering are the possible defects in the plaster surface.
Crazing is caused because of over troweling the mortar with high cement content. This can be covered easily with the reasonable quality paint with appropriate filler.
De bonding is due to different shrinkage rate through the plaster thickness and can be noticed if a hollow sound is heard when tapping the surface. The main reason for this type defect is the excessive thick plaster layers. Cleaning the surface well to remove dusts and oil, damp the wall properly and applying the cement slurry coat on the surface before plastering can be minimized the de bonding.
Lack of hardness can be observed only by scratching the surface and this is causing due to insufficient cement content, using the sand with excess dust and adding some more water after first mixing (re tempering).
Grinning is due to excess troweling.