Plaster of Paris mould-making

Updated April 17, 2017

Creating plaster of Paris can be very fun and rewarding. Follow these simple steps to create a mould from plaster of Paris.

Ingredients you'll need

Gather your materials. You'll need plaster powder, water, a bowl and spoon, plastic moulds and a craft or small knife.

How to make plaster

Place the plaster powder into a bowl or container. Follow the directions on the powder's box to determine how much water should be added, but as a rule, for every 256 g (2 cups) of plaster, add 237 ml (1 cup) of water. Once the water is added, slowly and thoroughly stir until it is well mixed. The more water, the longer it will take for the plaster to dry, but it will also be less heavy than plaster that is made with a thicker consistency.

Using plastic moulds

Spread a barrier on the mould so the plaster of Paris doesn''t stick to it after you pour it in. Petroleum jelly is a suitable option for a barrier. Spoon the plaster into the moulds that you would like to make. You can get plastic moulds of animals, plants or almost anything you desire at an arts-and-crafts shop. Plaster can take from 20 minutes to hours to dry, depending on the size of the mould, but you can touch the back of the plaster to see if it's hard or not.

Let it dry

Take the plaster out of the moulds carefully so that they are not damaged. If you notice any inconsistencies or imperfections you can use a small craft knife to slowly scrape off any plaster. After you are satisfied you can lay them out on a plate or rack overnight to harden.

Creating plaster moulds

If you can't find any moulds that you like, you can also make some out of plaster of Paris. All you have to do is mix the plaster as described in step 2 and pour it into a plastic bowl. Once you've decided on an object whose shape you like, you can carefully put it into the plaster mix. Make sure to cover all the object's sides with the plaster mix.

Using plaster moulds

Once the mould is completely dry, you are now ready to use it.

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