Kids, did you ever spill something on your furniture or carpet and be surprised when it was easy to clean up without leaving a stain? Some fabrics are treated with a very thin coating that repels liquids somewhat. In this experiment you will test such a coating by studying the absorbency of tissues both with and without a water repellent substance.

You will need a can of Scotchguard® spray, facial tissue, 2 clear plastic cups, 2 rubber bands, and water. You will also need proper ventilation because of the Scotchguard® spray fumes.

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

Open one tissue and drape over one of the cups. Push the center of the tissue slightly into the cup, forming a pocket. Secure it to the cup with a rubber band. Slowly pour some water into this pocket and observe what happens. Now spray a new tissue with Scotchguard®, let it dry, and repeat the experiment. What happens? Does this tissue cause different behavior?

Why does this happen? The spray forms a coating over the surface of the tissue. The coating is so smooth that any holes present are smaller even than tiny water molecules. Therefore water is not allowed to penetrate through the tissue. You can try this same test on different materials, such as pieces of scrap fabric.

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Kathleen Carrado Gregar, PhD, Argonne National Labs 
[email protected]
May 1995

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Reference: Phil Parratore inWacky Science: A Cookbook for Elementary Teachers, Kendall/Hunt Publishing Co. (Dubuque, Iowa), 1994, page 112.