5 important of Gypsum Plaster (Plaster of Paris)


Gypsum plaster is a versatile building material that has been used for thousands of years in construction projects around the world. It is a mixture of gypsum, water, and various additives that can be applied to walls and ceilings to create a smooth, durable surface. In this article, we will explore the history, composition, application, advantages, and disadvantages of gypsum plaster.

Gypsum Plaster (Plaster of Paris)

History of Gypsum Plaster

Gypsum plaster has been used since ancient times, with evidence of its use in ancient Egypt, Greece, and Rome. In fact, the word “plaster” comes from the Greek word “emplastos,” which means “to daub on.” The ancient Egyptians used gypsum to cover their mud-brick walls, while the Greeks and Romans used it to create intricate decorative elements in their buildings.

During the Middle Ages, it was widely used in Europe to create decorative plasterwork and to cover the walls and ceilings of castles and churches. In the 18th and 19th centuries, advances in manufacturing technology led to the production of high-quality plaster that was used in the construction of homes and public buildings.

Composition of Gypsum Plaster

it is made from gypsum, a naturally occurring mineral that is found in sedimentary rock formations around the world. Gypsum is composed of calcium sulfate dihydrate, which means it contains two molecules of water for every molecule of calcium sulfate.

To make gypsum plaster, the gypsum is first mined and then crushed into a fine powder. This powder is then mixed with water and various additives, such as lime, sand, and fibers, to create a smooth and workable paste. The paste is then applied to walls and ceilings using a trowel or a spray gun, and allowed to dry.

Application of Gypsum Plaster

Gypsum plaster can be applied to a wide range of surfaces, including concrete, brick, and drywall. It is often used as a finishing material for walls and ceilings because it creates a smooth and level surface that is easy to paint or wallpaper.

The application of gypsum plaster typically involves several steps. First, the surface to be plastered is cleaned and prepared by removing any loose or flaking material. Next, a primer is applied to the surface to help the plaster adhere. The plaster is then applied in several coats, with each coat allowed to dry before the next one is applied. Finally, the surface is sanded and smoothed to create a smooth and level finish.

Advantages of Gypsum Plaster

Gypsum plaster offers several advantages over other types of plaster and wall-covering materials. Some of the main advantages of gypsum plaster include:

1. Durability:

Gypsum plaster is a durable material that is resistant to cracking, shrinking, and warping.

it can withstand high levels of humidity and temperature changes, making it a good choice for use in bathrooms, kitchens, and other areas that are prone to moisture.

2. Fire resistance:

Gypsum plaster is highly fire-resistant, making it an ideal choice for use in buildings where fire safety is a concern. It can help to slow down the spread of fire and reduce the risk of structural damage.

3. Sound insulation:

Gypsum plaster has excellent sound-insulating properties, helping to reduce noise levels in homes and buildings. This makes it a good choice for use in bedrooms, music rooms, and other areas where noise reduction is important.

4. Aesthetics:

Gypsum plaster can be applied in a variety of textures and finishes, making it a versatile material that can be used to create a wide range of decorative effects.

5. Sustainability :

Gypsum plaster is an environmentally friendly material that is made from natural and recyclable materials. It is also energy-efficient, as it helps to insulate buildings and reduce heating and cooling costs.

Precautions of Gypsum Plaster

While gypsum plaster offers many advantages, there are also some Precautions to consider. Some of the main Precautions of gypsum plaster include:

1. Cost:

Gypsum plaster can be more expensive than other types of plaster and wall-covering materials, such as drywall or paint.

2. Installation time:

The installation of gypsum plaster can be time-consuming and labor-intensive, as it requires several coats and drying times.

3. Vulnerability to moisture:

While gypsum plaster is resistant to moisture, it can still be vulnerable to water damage if it is not properly installed or maintained. This can lead to mold and mildew growth, as well as structural damage.

4. Unsuitability for high-traffic areas:

Gypsum plaster may not be the best choice for high-traffic areas, such as hallways or stairwells, as it can be prone to dents and scratches.

What happens when gypsum is heated?

When gypsum is heated, it undergoes a chemical reaction known as “calcination,” which involves the removal of water molecules from the gypsum. The process of calcination converts the hydrated calcium sulfate (gypsum) into anhydrous calcium sulfate, which is a dry powder known as “plaster of Paris.”

During calcination, the gypsum is heated to a temperature of around 150-190°C (302-374°F) in a special kiln. As the temperature rises, the water molecules in the gypsum are driven off, leaving behind the anhydrous calcium sulfate powder.

The chemical equation for the calcination of gypsum can be written as:

CaSO4 · 2H2O → CaSO4 + 2H2O

Gypsum Plaster Plaster of Paris POP

In this equation, CaSO4 · 2H2O represents hydrated calcium sulfate (gypsum), which is heated to produce CaSO4 (anhydrous calcium sulfate) and 2H2O (water vapor).

Plaster of Paris, which is the product of calcination, is widely used in construction, art, and medicine. It can be mixed with water to form a paste that can be applied to walls and ceilings to create a smooth surface for painting or wallpapering. It is also used to make molds and casts in art and sculpture, as well as in the manufacture of orthopedic casts and bandages in medicine.

In summary, when gypsum is heated, it undergoes a chemical reaction called calcination, which removes water molecules and converts the hydrated calcium sulfate into anhydrous calcium sulfate (plaster of Paris).


Gypsum plaster is a versatile and durable building material that has been used for thousands of years in construction projects around the world.

It offers many advantages, including fire resistance, sound insulation, and aesthetic versatility. However, it also has some disadvantages, such as installation time and vulnerability to moisture.

When considering using gypsum plaster in a construction project, it is important to weigh the pros and cons carefully, and to ensure that it is installed properly by a qualified professional.

With proper installation and maintenance, gypsum plaster can provide a beautiful and long-lasting finish to walls and ceilings, and contribute to the overall comfort and safety of a building.

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