Articles

    The Incrediblob

    Kids, now it's time to use chemistry to make your own plastic ball. Cover a work surface with two layers of paper towels. Into a small plastic cup put one tablespoon of white liquid glue (like Elmer's®). Into another small cup put 1/2 teaspoon each of Epsom salts and water. Swirl the cup until no more Epsom salts will dissolve (if any is left undissolved at the bottom of the cup that's okay). Pour all the contents from the Epsom salts cup into the glue cup and stir it up with a plastic spoon. What happens to the mixture?

    Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.

    Scoop the mixture out onto the double thickness of paper towels, fold the towels over it and press down to absorb the extra water. Pick up your newly formed plastic and form it into a long roll. See how long you can make the roll without it breaking, and measure it's length. Form the plastic into a ball and flatten it down onto a piece of wax paper like a pancake. See how large a pancake shape you can make that can be lifted off the wax paper in one piece, and measure it's diameter.

    Form the plastic back into a ball and try bouncing it off a hard clean surface. Congratulations on making an incredible, incrediblob incrediball!

    Chemistry notes: Note how many different plastics you used to help make one of your own (the cups, the spoon). On the day you do this experiment, try to make a list of all the plastics you see that day and you'll be amazed at how long the list can be. Epsom salts are a chemical product called magnesium sulfate (MgSO4). You should have some left over from making the Epsom salt towers described in the last column. Try to work quickly in this experiment because your plastic material will dry out as you use it.

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    Kathleen Carrado Gregar, PhD, Argonne National Labs 
    [email protected]
    September 1999

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    Reference: "WonderScience" from the American Chemical Society, 1991, vol. 5(8), issue on plastics (ACS, 1155 Sixteenth St., N.W., Washington, DC 20036).