You may remember one of my Be Still photos that I snapped while teaching my college chemistry lab:

In this particular chemistry lab, my students were making slime or “gak.”  My own little students at home have fun making this creation as well, so I thought I would post the procedure for all of you to try at home!

Gak (this creation can go from slimy to bouncy-ball consistency depending on the ratio of ingredients used)

materials needed

• 8 oz. bottle of Elmer’s Glue
• 1 teaspoon of Borax (found in your grocer’s laundry aisle)
• warm water
• plastic cups or mixing bowls and plastic spoons for mixing
• food coloring

Procedure

Pour the entire bottle of glue into a mixing bowl.  Then fill up that empty bottle of glue with some warm water, swish it around, and dump that water into the mixing bowl with your glue.  Now add a couple drops of food coloring if you would like! Stir it well to mix.

In another mixing bowl (or plastic cup) place 1/2 cup of warm water plus 1 teaspoon of Borax. Stir well.

Slowly add the Borax solution to your glue.  Keep on stirring and keep on adding a little bit of the Borax solution.  Now get your hands dirty and knead the slime while still adding the Borax.  You will see that after several minutes of kneading, your slime will begin to take on a silly putty-like state.  Add the Borax solution to your liking–you can add all of it or just some of it!  Play around with different batches.  You can go from a really slimy consistency to a bouncy ball like state depending on how much Borax you add!

How it works

In this experiment, you are making polymers (long strands of molecules linked together like beads in a necklace.)  The Borax is a “linking agent” that links together the molecules found in the glue.  Once these glue molecules are linked together into long strands, you have formed polymers! These polymers are what give rise to the slimy, silly putty like texture of your gak.  As you keep cross-linking the molecules–by adding more Borax–you will get a less slimy and a bit denser gak.

Polymers play a very important role in our everyday lives.  Plastics are synthetic polymers that we use repeatedly throughout our everyday lives.  The DNA in our cells is a biological polymer that makes human life possible!  So have fun being a polymer chemist for the day.  Let me know how this experiment works for you, too.

[Please also use common sense and think about safety...no glue or borax in the eyes or mouth, and wash up when done! Be sure to read any and all warning labels on the glue and Borax containers. I don't let my kids handle the borax or borax-containing products for extended periods of time.]