What Is a Homemade Recipe for Plaster of Paris?

Plaster of Paris is made with the combination of warm water and calcium sulphate hemihydrate. The main ingredient in homemade plaster of Paris is still water, but substitute in flour instead of calcium sulphate hemihydrate.

• Warm 2 cups of water and slowly stir in 3 cups of white all-purpose flour. Continue stirring to remove any lumps, until the mixture has a smooth pudding texture.
• Quickly pour the plaster into the mold, and tap the bottom of the mold against a flat surface to encourage any air bubbles to rise.
• Smooth the surface with a wooden spoon or Popsicle stick. The mixture will begin to harden immediately, so it is important to rinse any tools and wash hands before it becomes difficult to remove.
• Allow the mold to sit in a warm area to dry overnight.

This same recipe can be used to make sidewalk chalk, except the mixture should be poured into smaller molds, with a few drops of food coloring stirred in to each container. Once the plaster is dry, the chalk is ready for use.