Carnegie Mellon University


This experiment (and the resulting toy) is another example of the important properties one can obtain when a network polymer absorbs water. PowerBalls™ are made by the Curiosity Kits Company. The exact polymer used is proprietary and therefore this information is not available. PowerBalls™ are available in toy stores and the internet.

Supplies needed:

  • Two-piece mold
  • Colored polymer crystals
  • Cup
  • Water
  • Waxed paper
  • Timer

Procedure (reference: Curiosity Kits)

1. Cover your work surface with waxed paper.

2. Snap the two parts of the mold together.


3. Choose the colors of polymer crystals you want to use. You can use more than one color to make a striped or swirled ball.

4. Carefully pour the crystals into the mold a little at a time, shaking the mold gently to help the crystals settle. Continue filling until the crystals reach the beginning of the spout.


5. Submerge the filled mold in a cup of water, up to the spout, for 1 minute. Do not completely submerge!


6. Remove the mold from the water and set on the waxed paper. DO NOT OPEN IT! Keep it closed for 3 more minutes.

7. Carefully pop open the mold and remove the ball. The ball will be sticky, so let it sit on the waxed paper for one minute to dry the surface.


The polymer crystals absorb water through the small holes in the mold. When the water is absorbed, the polymer becomes sticky and the crystals adhere to one another, taking on the shape of the mold. The resulting ball can bounce 10-15 feet high.

The PowerBall™ will dry out and harden (it loses water) if it is left in the air. To extend its lifetime, it must be stored in a sealed plastic bag when not in use.