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 withstand stretching and pulling as you mold it into a freeform sculpture.
Inflate the balloon to stretch out its walls, then deflate it.
This project can get quite messy so make sure to cover your work area with a large mat or some newspapers.
Mix 2 cups plaster of paris powder with 1 cup water or follow your brand's package instructions. Check out our Mixing Plaster of Paris page for mixing instructions with photos.
Use a funnel to pour the mixture into the squeeze bottle. If you used a paper bowl or an empty milk carton as a mixing container, you won't need a funnel—just pinch the bowl or carton at the mouth to create a lip, then carefully pour the contents into the squeeze bottle.
Turn the bottle upside-down and give it one big squeeze to fill the mixture into the balloon. Some notes on doing this step:
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.
The mixture will start to change in both consistency and temperature inside the balloon. When it starts to take on an almost gummy feel, you can start shaping it with your hands. As the plaster starts to solidify, you will notice that it also gives off heat. Finalize the shape of your sculpture before the plaster hardens. Hold the position of your hands until the sculpture sets.
This step is optional and you must wear a mask or a bandana to cover your nose and mouth.
Use medium grit sandpaper to smoothen the section where the balloon was tied and any other areas you want to smoothen. Do not blow off the dust to avoid getting them in your eyes and nose.
After Step 12, let your sculpture cure or dry completely for 48 hours. Because plaster of paris is an extremely porous material, it is important to apply a primer before painting. Apply a coat of acrylic gesso or slightly diluted white glue (3 parts glue to 1 part water). Let the primer to dry thoroughly before painting with acrylic paint. After the paint dries, seal with clear acrylic sealer.