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How to Dissolve Plaster

Plaster needs to be totally saturated in water for a chemical action to begin that allows the mixture to harden as it dries. It needs to be evenly dissolved without any air incorporation. The ratio for most plaster mixes is two parts plaster to one part water. Plaster mixes get warm and expand as they set. The air temperature and humidity affect this process.

Things You'll Need

Newspaper
Plaster of Paris powder
Water
Large plastic mixing bowl
Measuring cup
Wooden spoon

Instructions

- 1
  Cover your work area with newspaper to protect it from possible plaster spills.
- 2
  Measure water into a plastic mixing bowl. The ratio of plaster to water is 2 parts plaster to 1 part water. Be certain your bowl will hold three times the planned volume of plaster to facilitate proper mixing.
- 3
  Break up plaster clumps with a wooden spoon before adding it to the water. Some plaster powder will be free of these lumps, it depends on the storage conditions.
- 4
  Sprinkle plastic powder slowly into the water and notice how it sinks. Distribute it across the entire surface of the water as you gently add all the plaster.
- 5
  Soak the plaster for one minute by allowing it to sit undisturbed. This allows the plaster to become evenly saturated with water.
- 6
  Mix the plaster into the water slowly. Stir gently while mixing to limit air entering the mixture. Beating actions will cause air to get trapped in the plaster.
- 7
  Check any corners of your mixing container to be certain that all the plaster powder gets incorporated into the mixture.
- 8
  Tap the sides of the plastic mixing bowl gently with a wooden spoon to release any trapped air bubbles.

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