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The following defects may arise in plaster work
Blistering of plastered surface: This is the formation to small patches of plaster swelling out beyond the plastered surface, arising out of late slaking of lime particles in the plastic.
Cracking: cracking consists of cracks or fissures in the plaster work resulting from the following reasons:
- Imperfect preparation of background.
- Structural defects in building
- Discontinuity of surface.
- Movements in the background due to its thermal expansion or rapid drying.
- Movements in the plaster surface itself, either due to expansion (in case of gypsum plaster) or shrinkage (in case of lime – sand plaster).
- Excessive shrinkage due to application of thick coat.
- Faulty workmanship.
Crazing: It consists of formation of a series of hair cracks on plastered surface, due to dame reasons which cause cracking.
Efflorescence: It is the whitish crystalline substance which appears on the surface due to presence of salts in plaster – making materials as well as building materials like bricks, sand, cement etc. and even water. This gives a very bad appearance. It affects the adhesion of paint with wall surface. Efflorescence can be removed to some extent by dry brushing and washing the surface repeatedly.
Flaking: It is the formation of very loose mass of plastered surface, due to poor bond between successive coats.
Peeling: It is the complete dislocation of some portion of plastered surface, resulting in the formation of a patch. This also results from imperfect bond.
Popping: it is the formations of conical hole in the plastered surface due to presence of some particles which expand on setting.
Rust stains: These are sometimes formed when plaster is applied on metal laths.
Uneven surface: This is obtained purely due to poor workmanship.
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