In this Article we will discuss about plastering definition, purpose, requirement of good plaster and technical terms related to plastering
Definition of Plastering :
plastering is a layer provide over masonry or concrete surface for the purpose of protect wall and other concrete element against the atmospheric effect, and also provide finishing surface.
Technical Terms :
- Finishing Coat
The exiting surface on which the plastering layer is applied is known as background.
i.e. Masonry wall.
The plaster surface swell on some places, this defects is known as blistering of plaster.
Due to movement of wall the cracks is developed on the surface of plaster that is is known as cracking.
The groups of crack develop on plaster surface is known as crazing.
The Dado is define as the lower portion of plaster wall which consist 1 to 1.5 m height.
6. Finishing Coat
The topmost surface of plaster is known as finishing coat. generally plaster is done in two to three-layer.
When Plaster surface is separate to existing masonry surface due to low bonding of plaster surface and masonry surface. this defects is known as flaking.
when the mortar joints are clearly visible over the plaster wall, this defect is known as Grinning.
For the purpose of proper bond between plaster layer and masonry wall, making the masonry wall uneven, is known as hacking.
Purpose of Plastering
- making smooth surface of masonry
- Increase durability of masonry
- Provide plain surface for painting work
- Provide protection against atmospherics attack
- protect against moisture
- Provide better aesthetic view
Requirement of Good Plaster
- The surface of plaster should be smooth
- The surface of plaster should be non-absorbent
- The plaster surface should not wash by water
- Plaster should not shrink when it dries or freezes
- The shrinkage cracks is not developed in plaster
- The plaster should be firmly attached to the masonry surface
- The fire resistance of plaster should be good
- The plaster should be sound insulated
- The surface of the plaster should be paintable
Tools used for plaster
- Floating rule
- Plumb bob
- miscellaneous tool
A float is used to spread mortar or coal on the masonry surface. A wooden float is called a skimming float. It’s size around 30cm*10cm and thickness is 10mm.
2. Floating rule
Floating rule is used to check the surface level of plaster.
3. Plumb bob
A plumb bob is a pointed weight attached to the end of the string, which is used to locate a vertical reference line called plumb.
- Spirit level
- set square
- straight edges
Spirit level is an instrument designed to check whether a surface is vertical or horizontal, this instrument is also know as bubble level or simply level.
Same as Set Square is used to check wall is perpendicular or not.
How to apply plaster on wall
- Before applying plaster on the wall you need to clean the existing wall by use a brush, remove all dust, salts, and other rubbish materials.
- Check the crack is not develop in the masonry wall. If crack is developed then first fill the crack by using repair materials.
- Check the verticality of masonry wall by using tool which is discussed above.
- Apply water on the rough surface of masonry for the purpose of cleaning make sure the masonry wall properly soaked water. otherwise masonry will extract water from the plaster surface, due to that cracks may be developed in plaster.