Plaster of Paris Freeform Sculpture

Load Plaster of Paris mixture into a balloon and mold it with your hands as it hardens into an abstract or freeform sculpture.

Safety Tips

  • Plaster of Paris powder should be used under adult supervision. The powder is extremely fine and easily dispersed through air. Using a dust mask is highly recommended.
  • As a precaution, wear a pair of protective goggles.
  • Never mix Plaster of Paris with your bare hands.
  • Watch out for this sign Ask for an adult's help. It means adult help is needed for the particular step.
Plaster of Paris Freeform Sculpture craft

Materials

  • Oval balloon (medium or large)
  • Squeeze bottle (e.g. empty shampoo bottle)
  • Plaster of Paris powder
  • Water
  • Mixing container (Paper bowl or cardboard
    milk carton)
  • Spoon
  • Funnel
  • Medium grit sandpaper
  • Scissors
  • Paint brush (optional)
  • Acrylic paint or poster paint (optional)
  • Clear acrylic sealer (optional)

Steps

Step 1 Plaster of Paris Freeform Sculpture 1. One of the most important things in making this project is to find high-quality medium-sized or large balloons. The balloon should be sturdy enough to hold the Plaster of Paris mixture and to withstand stretching and pulling as you mold it into a freeform sculpture. Inflate the balloon in order to stretch out its walls, then deflate it.
Step 2 Plaster of Paris Freeform Sculpture 2. The other critical material that you need is a squeeze bottle. You can use empty shampoo bottles or purchase a cheap plastic squeeze bottle. The more squeezable it is, the better. You also have to check if the balloon's opening could fit on the bottle's mouth.
Step 3 Plaster of Paris Freeform Sculpture Ask for an adult's help3. Before mixing the Plaster of Paris, make sure you cover your work area with newspapers or with a large mat. This project can get very messy! Typically the ratio of the mixture is 2 parts Plaster of Paris powder to 1 part water. For this particular project we will need around 2 cups Plaster of Paris powder and 1 cup water. Mix according to package instructions or follow this basic mixing procedure.
Step 4 Plaster of Paris Freeform Sculpture 4. Use a funnel to transfer the mixture into your squeeze bottle. If you used a paper bowl or an empty cardboard milk carton as a mixing container, you won't need a funnel. Slightly pinch the paper bowl or milk carton on one side to create a lip and pour the contents directly into the squeeze bottle.
Step 5 Plaster of Paris Freeform Sculpture 5. Fit the deflated balloon's opening around the bottle's mouth. Try to ease the balloon down as close to the bottle's neck as it can go.
Step 6 Plaster of Paris Freeform Sculpture Ask for an adult's help6. Invert the bottle and give it one big squeeze to fill the mixture into the balloon. Push the mixture down the bottom of the balloon. Here are some helpful tips:
  • Squeezing repeatedly will just result in the mixture going back and forth between the bottle and the balloon. The best shot is to give it one giant squeeze.
  • A squeeze bottle full of Plaster mixture is easier to fill than a half-filled one because it contains less air.
  • A very squeezable bottle is a big plus!
  • A thinner mixture flows better and can be easily filled into the balloon. However, thinning down your mixture means that it will set slower and the resulting sculpture may not be as sturdy.
Step 7 Plaster of Paris Freeform Sculpture 7. Once you have filled as much of the mixture as you can into the balloon, carefully remove the balloon from the squeeze bottle. Release any trapped air by slightly loosening your grip on the balloon's opening. Allow the air to escape until some of the Plaster of Paris mixture is pushed out. This usually is an indication that you have removed all the air inside the balloon.
Step 8 Plaster of Paris Freeform Sculpture 8. Knot the balloon to seal it permanently. In case you have a lot of leftover mixture inside your squeeze bottle, you can still fill it into another balloon.

*Fill your squeeze bottle with water if you want to use it again, otherwise the bottle cannot be reused once any leftover Plaster hardens inside it.
Step 9a Plaster of Paris Freeform Sculpture 9. Observe the changes of the Plaster of Paris mixture inside the balloon. As a science activity, you can record any weight, consistency and temperature changes.

As an art activity, wait for the moment when the mixture starts to change in consistency inside the balloon. When it starts to take on an almost gummy feel, you can start shaping it with your hands.
Step 9b Plaster of Paris Freeform Sculpture Enjoy the tactile experience of shaping, stretching, twisting, and creating a unique freeform shape. It is pretty obvious in this photo why a sturdy balloon is a must! Bursting a balloon in the middle of shaping your sculpture can be very messy and frustrating.
Step 9c Plaster of Paris Freeform Sculpture You will notice that the mixture releases heat as it solidifies and the phase change occurs in a matter of minutes. Keep in mind that once your sculpture starts to give off heat, it is a signal that you should be wrapping up your sculpture's final shape.
Step 9d Plaster of Paris Freeform Sculpture   Here's another idea - mold a second sculpture around your first one to make interlocking pieces.

Allow your sculptures to set for at least 4 hours.
Step 10 Plaster of Paris Freeform Sculpture 10. After your sculpture has set completely, carefully cut the balloon to reveal your sculpture.
Step 11 Plaster of Paris Freeform Sculpture 11. Sand off the area where the balloon was tied. Do not blow off the dust because you might inhale them.
Step 12 Plaster of Paris Freeform Sculpture Ask for an adult's help12. That's it! You have just finished a freeform sculpture out of Plaster of Paris. To waterproof your work, spray on a coat of clear acrylic sealer on the entire sculpture.
Step 13a Plaster of Paris Freeform Sculpture 13. If you want a colored sculpture, you can paint it with acrylic paint or poster paint. Do not add water to paint as this may soften the Plaster of Paris. Solid colors are pretty easy to do and they can give your sculpture a very modern look.

Your sculpture can be a great gift for your dad on Father's Day. He can use it as a very stylish paper weight or display it on his desk as a work of art.
Step 13b Plaster of Paris Freeform Sculpture You can also think of your sculpture as a blank canvas - you can paint on anything you like!

Waterproof your work with clear acrylic sealer after the paint has completely dried.

Earth Friendly Tips

  • Do not throw Plaster of Paris into the drain, it will clog the pipes. If you have any leftover mixture, let it harden, then throw it into a garbage can.
  • If you want to save spoons or containers used for mixing Plaster of Paris, scrape off the hardened plaster and wipe the utensils with a damp cloth.

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