Bouncy, Bouncy, Bouncy Balls

As a child, I always loved playing with Bouncy Balls. However, I always wondered “what makes them so bouncy”? Well my lab partner and I were determined to find that out. We knew that a good Bouncy Ball  can’t be to big, has to be able to hold it’s shape, and must be very bouncy of course. To begin our experiment we gathered our ingredients: Elmer’s Glue, and Sodium Borate mixed with distilled water.  We knew that the proportions of each ingredient were going to be very important in making our Ball. If we put too much glue the ball might not hold it’s shape. The first time we tried the experiment we added 100 milliliters of water to 10 grams of Sodium Borate and mixed it until the Sodium Borate was dissolved. We then mixed this with 20 grams of Elmer’s glue. I then rolled this mixture around in my hands until it formed into a ball. This took 5-10 minutes. Unfortunately, this ball did not bounce very high, and it wouldn’t hold its shape. We thought less glue might work better. For our next ball we mixed 10 grams of Borax solution with only 15 grams of glue. This ball was able to bounce much higher, 40 cm off the ground, and it held its shape. Knowing this was the type of ball we wanted we made two more with the same proportions of ingredients. The only change was we added two drops of yellow food coloring to the Elmer’s glue before mixing in order to give the ball some color. My partner and I figured out the best proportions of ingredients by trial and error and logical thinking. We had to try different proportions of glue, each time evaluating whether the Ball would benefit from more or less. This method matters because it was effective in creating a good Bouncy Ball.  Even after all these years, Bouncy Balls still manage to make me smile.