How to Prepare Dental Plaster of Paris

Plaster of Paris not only can make impressions of fossils, but dentists use it for creating casts, models and other laboratory applications where strength does not matter. Careful preparation of dental plaster of Paris ensures that the final product sets and performs as expected. When properly cured, dental plaster of Paris' strength rates at 2,600 pounds per square inch.

Things You'll Need

• Dental plaster of Paris
• Water
• Scale
• Rubber spatula
• Bowl with rounded bottom
• Mold

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Instructions

• 1

  Shake the container of plaster of Paris to redistribute the contents and ensure proper mixing. Refer to the manufacturer's instructions for mixing the plaster of Paris. Adhere to these guidelines as they vary by the maker, and the desired strength of the finished product depends on the amount of water used. Use too much water and the hardened plaster is weak.

• 2

  Measure out the required water and pour it first into the bowl. Pour out only the amount of water immediately needed into the bowl, as plaster of Paris hardens after mixing.

• 3

  Use a scale to carefully weigh the proper ratio of plaster of Paris powder, and sift or pour into the water slowly while stirring the water with the spatula. Continue to slowly stir the mixture without pulling the spatula out of the mixture until all of the plaster of Paris combines with the water. Avoid producing air bubbles, which cause weakness in the finished product.

• 4

  Pour the dental plaster of Paris into the mold and allow to sit for five to 10 minutes to harden enough for carving, if desired. Let the plaster harden up to one hour for the greatest strength.