How Do You Harden Plaster of Paris?

By Michael Ferguson

Plaster of Paris is a popular material that is commonly used for creating sculptures, molds, and other decorative objects. However, it can be prone to breaking or chipping if it is not hardened properly. In this tutorial, we will discuss some methods that you can use to harden plaster of Paris.

Method 1: Using Heat

One way to harden plaster of Paris is by using heat. To do this, preheat your oven to 350 degrees Fahrenheit.

Once the oven has heated up, place your plaster object inside for around 30 minutes. Keep an eye on it during this time to ensure that it doesn’t overheat or crack.

Tips:

  • Make sure that the plaster object is completely dry before placing it in the oven.
  • Avoid using this method for objects that have delicate features or details that could be damaged by the heat.

Method 2: Using Glue

Another method for hardening plaster of Paris is by using glue. Simply mix a small amount of white glue with water and apply it to the surface of your plaster object with a paintbrush. Allow the glue to dry completely before handling your object.

  • Use a high-quality white glue, such as Elmer’s Glue-All or Aleene’s Tacky Glue.
  • Avoid applying too much glue at once as this could cause cracking or warping.

Method 3: Using Salt

You can also harden plaster of Paris by adding salt to your mixture before pouring it into your mold. Simply mix a tablespoon of salt per cup of plaster into your mixture and stir well. The salt will help to harden the plaster and make it less prone to breaking.

  • Avoid using too much salt as this could cause your mixture to set too quickly.
  • Be sure to mix the salt thoroughly into your plaster mixture to ensure even hardening.

Method 4: Using Acrylic Sealer

Finally, you can use an acrylic sealer to harden your plaster of Paris object. Apply a thin layer of sealer to the surface of your object with a paintbrush and allow it to dry completely. Repeat this process several times until you have achieved the desired level of hardness.

  • Choose a high-quality acrylic sealer that is designed for use on porous surfaces like plaster.
  • Be sure to apply thin, even layers of sealer to avoid cracking or warping.

In conclusion, there are several methods that you can use to harden plaster of Paris. Whether you choose heat, glue, salt, or acrylic sealer, be sure to follow the instructions carefully and take your time to ensure that your object is hardened properly. With these tips and tricks, you’ll be able to create beautiful and durable plaster objects that will last for years to come.