Is Plaster of Paris Fireproof?

In this article, we will discuss if plaster of Paris is fireproof. Plaster of Paris or also referred to as POP, is a material that is commonly used for building, crafting, molding, and many more. It is easy to use and you can purchase it at your local hardware store. There are many benefits that you can get from using this material. However, is it fireproof? We will find out the answer below.

Is plaster of Paris fireproof? Plaster of Paris is fireproof and is also a material that is ideal for heat insulation. The good thing about this material is that it does not shrink while it sets. Hence, it does not develop cracks as it heats and sets. Its main component is gypsum.

What happens when the plaster of Paris is heated? Is plaster of Paris flammable? What are the different types of Plaster of Paris? Is plaster of Paris dangerous? These are some of the questions that we will discuss. You can check out the rest of the article below.

Is plaster of Paris fireproof
Photo by Ksenia Chernaya from Pexels

Is Plaster of Paris Flammable?

Plaster of Paris is non-flammable. It is also non-combustible. Plaster of Paris has a low chemical reactivity and under extreme conditions, it also acts as an oxidizing agent. At high temperatures, the plaster of Paris decomposes to generate toxic oxides of sulfur.

What Happens when Plaster of Paris is Heated?

When plaster of Paris is exposed to heat that is beyond 120°C, it starts to lose water, and sulphate is formed. This is also referred to as dead burnt plaster.

Can Plaster of Paris Go in Oven?

Plaster of Paris can go in an oven. This material is often used in casts that dry when exposed to air at room temperature. Aside from that, they can also dry in a warm oven at about 150 degrees Fahrenheit. On the other hand, avoid placing it in an oven with very high temperatures. Otherwise, it can crack and result in spalling.

Is Plaster of Paris Used as a Fireproof Material?

Plaster of Paris is a fireproof material because of its low thermal conductivity. Aside from that, it is also a very good heat-insulating material.

Why Does Plaster of Paris Get Hot?

When plaster of Paris gets hot, it undergoes a reaction. To create plaster of Paris, gypsum is heated to 150 degrees centigrade. When exposed to this temperature, the mineral dehydrates partially and 75% of the water content escapes and becomes water vapor. Re-adding water to plaster of Paris resets it into a gypsum crystal lattice and goes through an exothermic reaction and creates heat.

Is Plaster of Paris and Gypsum Plaster the Same?

There are differences between plaster of Paris and gypsum. The main difference is in the chemical formula as well as the composition of the Plaster of Paris and gypsum. For instance, gypsum is made of calcium sulphate dihydrate. On the other hand, plaster of Paris contains calcium sulfate hemihydrate. You can also check out this article that discusses what happens if plaster of Paris gets wet. We have shared useful tips and ideas that you can refer to when working with plaster of Paris.

Benefits of Using Plaster of Paris

There are many benefits that you can get from using plaster of Paris. It is used in crafting, sculpting, molding, and building. Plaster of Paris has gypsum as its main component. It is a building material that is mainly used for coating walls and ceilings and creating architectural designs. Moreover, plaster of Paris is a dry powder that is mixed with water and forms a paste or slurry when used. Below are some of the benefits of plaster of Paris.

  • Lightweight, durable, and has low thermal conductivity.
  • Has good adhesion on fibrous materials and provides a firm surface for colors to easily settle.
  • Fire-resistant and is a good material for heat insulation.
  • Easily mixes with water, is easy to spread, and level.
  • Do not shrink or develop cracks while heating or setting.
  • Forms a thick surface after drying.

✅ Video – How to Mix Plaster of Paris

Satyen Sharma shared the video below on YouTube. It shows how to mix plaster of Paris. In the video below, the perfect ratio that is required to mix plaster of Paris is discussed. Check out the video for more information.

What are the Different Types of Plaster of Paris?

Lime plaster, gypsum plaster, and cement plaster are the three different types of plaster of Paris. Let us learn more about these different types below.

Gypsum Plaster

This type of plaster is made by heating gypsum at 300 degrees Fahrenheit. It can turn into anhydrite when heated above 392 degrees Fahrenheit. Mixing water with gypsum plaster powder turns it into gypsum.

Lime Plaster

This is another type of plaster of Paris that you can use. Lime Plaster is the mixture of calcium hydroxide, sand, and other inert fillers. This is also called wet putty or white powder. To make quick lime, limestone is heated. Then, adding water into the quick lime creates slaked lime.

Cement Plaster

When suitable plaster, sand, Portland cement, and water is mixed, it is called cement plaster. Cement plaster is commonly used in exteriors and interiors to have a smooth surface. Most of the time, a final layer of gypsum plaster is added over the cement plaster. You can also check out this article titled, can I mix white cement and plaster of Paris? We have shared an in-depth discussion about the topic.

What are the Uses of Plaster of Paris?

Plaster of Paris is used in many applications like building materials, molding and casting, arts and crafts, and fireproofing. Let us learn more about these applications below.

Building Material

Plaster of Paris is commonly used as a building material. It is used as a protective coating on the ceilings and walls and is done before painting. Moreover, it provides a smooth surface and also helps in fireproofing.

Molding and Casting

Plaster of Paris makes an excellent molding and casting material. You can use it to make statues, showpieces, and other decorative items. You can also check out this article that discusses if cement is stronger than plaster of Paris. We have shared an in-depth discussion about the topic.

Art and Crafts

You can also use plaster of Paris for arts and crafts. It is used by both children and adults for doing art and craft projects. Aside from that, it is used by artists to make stunning art designs and patterns.


Another use of Plaster of Paris is in fireproofing. It is fire-resistant and is commonly used in buildings, fireproofing products, as well as fire protection systems. Furthermore, Plaster of Paris stops the spread of fire because the plaster coating discharges water vapor. It also offers protection by slowing down the heat transfer which prevents material breakdown.

Is Plaster of Paris Dangerous?

Plaster of Paris can be dangerous and harmful when it is not properly handled. This is because it is composed of calcium sulfate hemihydrates with asbestos, silica, and other impurities. When you accidentally inhale plaster of Paris, it can result in permanent lung damage and other health issues. Furthermore, mixing plaster of Paris and water can be harmful when not properly done.

On the other hand, it is commonly used by kids for crafting and arts. You need to follow safety precautions when handling plaster of Paris. Prevent inhaling the powder by wearing a face mask. You also need to wear gloves to avoid skin contact hat can cause skin allergies. Avoid washing plaster of Paris down the drain because it can clog the pipes when it dry.

Is Lath and Plaster Fire Resistant?

Lath and plaster are fire resistant and are usually used in ceilings to prevent fire spread. In the case of fire, the longer the plastered ceiling remains in place, the greater the fire will be prevented to spread between floor levels. On the other hand, there is limited data published regarding the fire resistance of lath and plaster ceilings. You can also check out this article titled, how to make plaster of Paris stronger? We have shared tips and ideas on how you can create a durable and strong plaster of Paris for your building and casting needs.

Do I Need Fireproof Plasterboard?

Whether you need fireproof plasterboard or not will depend on your needs and preferences. Usually, you need two layers of plasterboard with a skim according to the required fire resistance. Take note that having any kind of plasterboard is better than having no plasterboard at all.

Does Plaster of Paris Easily Break?

Plaster of Paris does not easily break. It is made from finely ground gypsum and is heated to 160 degrees. The plaster of Paris can be easily manipulated in many ways when it is mixed with water. You can use it to create sculptures, casts, and molds. When you heat the plaster of Paris in an oven, make sure that you use the recommended heat to prevent damaging the plaster. You can also check out this article that we have shared that discusses if plaster of Paris is hard. We have shared an in-depth discussion about the topic.


In this article, we have discussed if plaster of Paris is fireproof. We have found out that the plaster of Paris is fireproof and is used for making fireproofing products. If plaster of Paris is exposed to flame, it releases water vapor that slows the spread of the fire depending on its thickness. We hope that this article has helped you learn more about the plaster of Paris and its fireproof characteristics. Thank you for reading!

Recent Posts