Plaster is a pasty composition (in the form of lime or gypsum, water, sand, etc.) that hardens when used for drying and coating walls, ceilings, and partitions.
To protect the entry of rainwater and other environmental agencies, plastering is the process of placing a thin covering of cement mortar on the exposed surface.
It improves the appearance of the structure and gives a decorative effect to the interiors.
In walls plaster, it is necessary that there must be a proper bond with the masonry surface to plaster.
Types of plaster:
It is a mixture of sand, portland cement, and water; sometimes applied to masonry interiors and exteriors to acquire a smooth surface.
Interior surfaces are occasionally provided with a final layer of gypsum plasters.
Walls constructed with stock bricks are usually plastered, while brick walls are not encountered.
The surface should be prepared in the same manner as for lime plasters or cement plasters.
Usually, clay plasters are applied in two coats, the primary coat is 18 mm thick whereas the thickness of the second coat is 6 mm.
Gypsum plaster is widely used plasters material that can be mined naturally or produced as a by-product.
It is employed as an undercoat, finish coat, and lime and cement have been largely replaced.
Alum and cleaning soap react chemically and seal the holes within the plasters.
It is prepared by mixing equal quantities of lime and sand.
The boiled solution of vine fruit (in 3 litres of 100 litres of water and a ratio of 1.5 kg vine fruit), sometimes with a jug and roped hemp at the rate of 1 to 2 kg per cubic meter of mortar, is added.
Plaster of Paris:
Plaster of Paris is obtained from gypsum, a naturally occurring material.
When the gypsum is heated to a certain temperature, the crystallization water supersedes a very fine powder of the Plaster of Paris.
When water is added to this powder, it sets immediately, therefore, it is used for plastering, the setting time being extended by adding some salts, some burnt ash and fine sand.
A dry mixture of plaster of Paris and sand is prepared on a platform, this mixture is taken in a small amount in a lee pan and an appropriate amount of water is added. This plaster is applied in addition to water within 5 minutes.
This kind of plasters produces a very nice smooth finish with sharp edges and corners, it is not used for exterior surfaces.
This Plaster is an excellent decorative plaster, which is used on both interior and exterior walls.
The first coat, known as a rough coat, acts as a wall-clad and provides the desired strength.
The second coat, known as the finer coat, gives the surface the desired shape and the third coat, called the final coat, gives the required texture, smoothness and decorative appearance.
Heat resistant plaster:
It is a building material used for coating walls and chimney breast, its function is to replace the conventional gypsum plasters.
It is used in places where the temperature is too high or higher than 50 ° C to remain on the gypsum plasters wall.
It is required to protect the masonry wall from damp moisture and thereby destroy or reduce wall moisture.
The plasters consist of a mixture of cement and sand 1: 2, pulsed alum is added at a rate of 12 kg per cubic meter of sand. Soft sap is added to the water for mixing at a rate of 75 grams per litre.
Composite plaster is prepared by mixing cement, lime, pozzolana and sand in various proportions.
The plasters are applied on the exterior or internal surfaces in numerous thicknesses in a single or two coats as required.
Special mix plasters are required to provide decorative features to the surface of the walls and for particular functions such as water-proofing, restricted drainage, and so forth.
Plaster is provided as a decorative function where required; it is manufactured from three coats with a thickness of 25 mm.
The first coat, 10 mm thick, is called a scratch coat, the second coat, which is also 10 mm thick, is known as the brown coat.
The finishing coat or final coat is 4- 6 mm thick and is known as a white coat.
The mixture used in the first and second coats is about 10 per cent weight hydrated lime with 1: 3 cement and sand.
The finishing coat is a mixture of 1: 2 cement sand mortar. Generally, white or coloured cement is used to acquire a decorative characteristic.
Uses of Plaster:
Architecture: Plasters can also be used to create intricate detailing for use in room interiors.
In modern days these materials can also be used for false ceilings.
Art: Many great murals in Europe, such as Michelangelo’s Sistine Chapel ceiling, are painted on a thin layer of wet plasters.
Fire protection: As fireproofing products, ointments have been used in passive fire protection.
The finished plasters releases the water vapour when exposed to flames.
Advantages of Plaster:
- Easy to implement.
- No operation is required.
- Plasters are the most common form of interior wall finishing.
- If properly mixed and applied, a plasters coating makes a stronger and more durable.
Disadvantages of Plaster:
- When the plasters bursts, it is difficult to repair.
- It is very expensive to repair.
- Despite the extra labour of hanging and finishing the drywall, it is less expensive than plastering.
Frequently Asked Questions:
What do you mean by plaster?
Plaster is a smooth paste made of sand, lime, and water that hardens upon drying.
What is the use of plaster?
Plaster is a construction material used for coating, protecting and decorating interior walls and ceilings.
What is plaster made up of?
The most common types of plaster are mainly gypsum, lime or cement, etc.
How expensive is plaster?
The new plaster costs about $ 800 for a 100-square-foot surface, while a re-surface of the same size will cost $ 1,200 or more.
Plaster is a very efficient holding technique, though it is an easy concept, like any other technique it requires practice and attention.