Types of Plaster Finishes for Interior and Exterior Walls

What is Plaster Finishes?

Having your walls up is not the end of the building construction process. If you want to decorate your walls or cover their uneven surfaces, your contractors can finish your building with plaster.

Plastering is the process wherein the coarse surfaces of your walls or ceilings are covered to achieve a smooth and aesthetic finish.

There are several types of plaster finishes, and in this article, we will tell you how to achieve five different styles. Every finish gives your wall a different appearance, and it’s up to you to choose which one to use in your project.

What Is Plastering?

Plastering is the process of applying plaster to internal walls. Plaster is a construction material that coats and protects the inside walls and ceilings.

It is also used to decorate the walls as it can be formed into crown cornices, ceiling roses, corbels and other architectural mouldings. Plaster comes in a powdered form. You must add water to it before application.

Plaster can be of various types. Typically, you need multiple coatings of plaster to ensure maximum strength and durability to your walls.

Types of Plaster Finishes

After the application of plaster, finishing applied on the final coat of plaster following are some of the finishes.

1. Smooth Coat Finish.
2. Sand Face Finish.
3. Rough Cast Finish or Spatter Dash Finish.
4. Peddle Dash or Day Dash Finish.
5. Depeter Finish.
6. Scrapped Finish.
7. Textured Finish.
8. Special Material Used in Plastering for Finishing Coat.
   1. Acoustic Plaster.
   2. Asbestos marble Plaster.
   3. Barium Plaster.
   4. Granite Silicone Plaster.
   5. Plaster of Paris of Gypsum Plaster.
   6. Keene’s Cement Plaster.

1. Smooth Coat Finish

In this type of finish, the finishing coat is a smooth and levelled surface. The mortar used is made of cement and fine sand 1:3. Mortar is applied with the help of wooden float.

2. Sand Faced Finish

Sand faced finish is applied in two coats. The first coat is applied in 1:4 cement sand mortar of 12 mm thickness.

It is provided wish zig-zing lines. After curing it for seven days, the second coat is applied in the thickness of 8 mm.

The mortar for a second coat is prepared from the cement sand mix ratio 1:1. The sand of uniform size is used. A sponge is used in a second coat when it is wet.

The surface of the final coat is finished by rubbing clean and washed sand of uniform size by means of wooden float. This results in the surface having sand grains of equal and uniform density.

3. Rough Cast Finish or Spatter Dash Finish

1:1:3 = Cement: Sand: Aggregate are used to prepare mortar for this type of finish. The coarse aggregate may vary from 3 mm to 12 mm in size.

The mortar is thrown on the prepared plaster surface then by means of a large trowel. The surface is then roughly finished using a wooden float.

This finish is water-proof, durable, and resistant to cracking and crazing. It is used for external rendering.

4. Peddle Dash or Day Dash Finish

In this finish, clean pebbles of size from 10 to 20 mm size are dashed against the final coat of plaster.

The pebbles may be lightly pressed into the mortar with the help of wooden float. The final coat of plaster is having Cement: sand mix proportion of 1:3 and thickens 12 mm.

5. Depeter Finish

In this type of final finish coat of plaster is applied to have thickness 12 mm, and when it is a wet condition, the pieces of gravel flint are pressed with hand on the surface. Flints of different colours may be used to obtain beautiful patterns.

6. Scrapped Finish

The final coat of plaster of 6 to 12 mm applied. Then it is allowed to be stiffened for a few hours. The surface is scrapped in a pattern for a depth 3 mm.

Steel straight edge old saw blades or such other tools may be used for scrap. Such a scrapped surface is less liable to cracks.

7. Textured Finish

This is used with sketch plastering ornamental patterns or textured surface are made on the final coat of stucco plastering by working with suitable tools.

8. Special Material Used in Plastering for Finishing Coat

To meet with some specific requirements of finished surfaces such as durability better appearance, fireproofing, heat insulation, etc. special materials are added in mortar.

The following are the special materials to be used.

1. Acoustic Plaster.
2. Asbestos marble Plaster.
3. Barium Plaster.
4. Granite Silicone Plaster.
5. Plaster of Paris of Gypsum Plaster.
6. Keene’s Cement Plaster.

8.1. Acoustic Plaster

The materials like gypsum mixtures are added in mortar for finishing coat such a coat undergoes a chemical reaction and produces gas bubbles and due to the bubbles tiny openings are formed in the coat and it appears like a honeycomb.

These honeycomb minute openings absorb sound. Such plaster is useful in interior walls of halls auditorium etc.

8.2. Asbestos Marble Plaster

For a better appearance of finishing coat, mortar is made of cement asbestos and finely crushed marble and applied as finishing coat.

8.3. Barium Plaster

To protect persons working in X-ray rooms from radioactivity, finishing coat is applied with mortar made of cement, sand, and barium soleplate.

8.4. Granite Silicon Plaster

Granite and silicon are mixed with mortar.  This finish is used for a superior type of construction. It is a quick setting and elastic in nature. This eliminates cracks.

8.5. Plaster of Paris of Gypsum Plaster

Ground gypsum is heated at 160^o to 170^o C to obtain plaster of parish. Plaster of Paris hardens with 3 to 4 minutes of adding water.

Suitable retarders are added to increase setting time. Plater of a parish is generally used in combination with lime for ornamental work and reporting carks.

Gypsum plaster has fire resistance, light weight. It does not shrink while setting. It has a sound-insulating properly. It is very useful for ornamental work. However, gypsum plaster is soluble in water.

8.6. Keene’s Cement Plaster

Kenees’s cement is obtained by calcination of plaster of Paris with alum. This is very hard and sets in a few days taking a white glass-like polish. It is useful for decorative work.

Frequently Asked Questions (FAQ)

What is plastering?

Plastering is the process of applying plaster to internal walls and ceilings to create a smooth, protective, and decorative surface.

Why is plaster used in construction?

Plaster is used to cover coarse surfaces, protect walls, and add aesthetic value. It can also be formed into architectural mouldings like crown cornices, ceiling roses, and corbels.

What materials are used in plastering?

Plaster typically comes in powdered form and is mixed with water before application. Various types of plaster can be used, including cement, sand, gypsum, and special materials like acoustic plaster and granite silicone plaster.

How many coatings of plaster are usually needed?

Multiple coatings of plaster are generally needed to ensure maximum strength and durability for the walls.

What are the different types of plaster finishes?

The different types of plaster finishes include:

1. Smooth Coat Finish
2. Sand Faced Finish
3. Rough Cast Finish or Spatter Dash Finish
4. Peddle Dash or Day Dash Finish
5. Depeter Finish
6. Scrapped Finish
7. Textured Finish

What is a Smooth Coat Finish?

A Smooth Coat Finish involves applying a mortar made of cement and fine sand (1:3 ratio) with a wooden float to achieve a smooth and levelled surface.

What is a Sand Faced Finish?

A Sand Faced Finish is applied in two coats using cement sand mortar. The surface is finished with clean and washed sand to create a uniform, grainy texture.

What is a Rough Cast Finish or Spatter Dash Finish?

This finish uses a mortar mix of cement, sand, and aggregate (1:1:3). The mortar is thrown onto the surface and roughly finished with a wooden float. It is durable, waterproof, and resistant to cracking.

What is a Peddle Dash or Day Dash Finish?

In this finish, clean pebbles are pressed into the final coat of plaster. The plaster has a cement-sand mix proportion of 1:3 and is 12 mm thick.

What is a Depeter Finish?

A Depeter Finish involves pressing pieces of gravel flint into a wet plaster surface. Flints of different colors can create beautiful patterns.

What is a Scrapped Finish?

A Scrapped Finish involves scraping the final coat of plaster (6 to 12 mm thick) with tools like steel straight edges or saw blades to create a patterned surface.

What is a Textured Finish?

A Textured Finish involves creating ornamental patterns or textured surfaces on the final coat of stucco plaster using suitable tools.

What special materials can be used in plastering for the finishing coat?

Special materials include:

1. Acoustic Plaster
2. Asbestos Marble Plaster
3. Barium Plaster
4. Granite Silicone Plaster
5. Plaster of Paris (Gypsum Plaster)
6. Keene’s Cement Plaster

What is Acoustic Plaster?

Acoustic Plaster contains gypsum mixtures that create tiny openings in the coat, absorbing sound. It is useful for interior walls of halls and auditoriums.

What is Asbestos Marble Plaster?

Asbestos Marble Plaster uses a mix of cement, asbestos, and finely crushed marble for a better appearance in the finishing coat.

What is Barium Plaster?

Barium Plaster is used in X-ray rooms to protect against radioactivity. The mortar is made of cement, sand, and barium soleplate.

What is Granite Silicone Plaster?

Granite and silicon are mixed into the mortar for a quick-setting, elastic finish that eliminates cracks. It is used for superior types of construction.

What is Plaster of Paris (Gypsum Plaster)?

Plaster of Paris is made from ground gypsum heated to 160-170°C. It hardens quickly, has fire resistance, and is used for ornamental work. However, it is soluble in water.

What is Keene’s Cement Plaster?

Keene’s Cement is made by calcining plaster of Paris with alum. It sets into a hard, white, glass-like polish in a few days and is useful for decorative work.