How To Make Casting Plaster

Casting plaster is a method of making molds and casts. It’s fun and quite messy, but thoroughly enjoyable nonetheless.

You can make casting plaster in two ways:
Casting plaster using alginate. This is a seaweed extract that is used to make molds and castings.

  1. Rub the model’s arm liberally with petroleum jelly beginning from the elbow down to the hand.
  2. Using a whisk and a bowl, mix alginate and water together until it reaches a thick but semi-fluid consistency. When you’re done, take a handful of the purple mixture and spread it over the whole hand. Make several layers then stabilize it by using bandage all over the model's hand.
  3. Then, make a small opening by the side of the hand and let it set.
  4. Once it has hardened, start opening the cast by making very careful slits along the side where the opening was first made. Take your time in pulling off the mold until it’s totally pulled out of the model’s hand. You can also tell the model to wiggle his hand slowly.
  5. Now comes the crucial part when the mold is off the model’s hand because alginate shrinks and deforms very easily. Cover the mold with three layers of plaster to support the freshly removed mold. Let it harden for one day before removing the bandage and the alginate.
  6. Now you have a perfect plaster cast of a human hand.

Casting plaster using Plaster of Paris. This is the safest way of making memories. For example, while charting the growing years of your children, you can make plaster casts of their hands and feet as they grow in time.

  1. Begin by spreading old newspaper on your working area.
  2. Then combine plastic of Paris powder and water in equal 50/50 parts.
  3. Now take an aluminum pan – the kind that is used for baking cookies- and cover the surface with wax paper. Take your model’s hand and coat it thickly with petroleum jelly. Now place the hand flat on top of the wax paper and make your first coating by covering it with plaster of Paris.
  4. Let it dry for a moment while telling your model to stay very still.
  5. After that, proceed with your second layer and cover the same part with the remaining plaster of Paris.
  6. Allow it to dry and set your timer for 10 minutes. After the allotted time has passed, you can slowly remove the mold from your model’s hand. Make sure glue is within easy reach just in case some parts of the mold fall off while the plaster is being removed.
  7. Once it’s removed, place the cast palm up in a baking pan of filled with water all the while making sure that the water does not seep into inside of the plaster.
  8. Now in a separate bowl, mix water and dishwashing liquid. Dip a paintbrush into the soapy foam and proceed to coat the internal portion of the mold while it’s resting in water.
  9. After 5 minutes, remove the mold from the water.
  10. Now take another batch of the plaster of Paris powder and water and mix this together. When you’re done, pour this inside the mold then leave it as is for an hour.
  11. Once it has hardened, you can start slowly and carefully chipping away at the mold using a chisel to reveal a perfectly cast hand.
  12. To make it look super cute, embellish the hand with glitter or colored crystal gems.     

Now that’s the power of imagination!


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