Mixing up a batch of plaster of Paris is pretty easy. Once it's poured, it can take 20 to 30 minutes for it to set up and get hard. However, there are times when speeding up the plaster's setting or hardening time is important. For instance, if you work on a forensic team and you have to make plaster castings of footprints or tire treads at a crime scene. Naturalists who collect and study animal tracks by casting them out in the wild, may not have time to wait around for plaster to dry. One of the most crucial times when plaster is needed to set up faster than normal is when doing a life mask. Many people get claustrophobic when their face is encased in plaster. The faster they can get a plaster mold off their face, the happier they are.
Things You'll Need
- Plaster of Paris
- Measuring cup
- Measuring spoons
- Flexible bowl
Measure the plaster and water by volume, two parts plaster to one part water. For instance, measure out 2 cups of water and add 4 cups of plaster of Paris.
Pour the water into a flexible container like a plastic bowl. Put on a dust mask and sift the dry plaster of Paris into the water.
Add a teaspoon of salt to speed up the setting time.
Mix the plaster, salt and water thoroughly with a bare hand. Tap the outside of the container to bring trapped air bubbles to the surface.
Pour the liquid plaster.