Flubber By Marilyn Duerst Introduction: Here is a simple recipe to make your own Flubber. The creation does not have a personality of course, but you can have fun while learning about different properties of solids and liquids! Materials: tsp guar gum powder 80 mL distilled water (about 1/3 cup) 1 tsp saturated borax solution 1–2 drops food coloring Craft stick Plastic cup Zipper storage bag 1/ 4 *Get guar gum from a natural foods store or order from Flinn Scientific or other supply place. 3. Add about 1 teaspoonful of your borax solution to the water/guar gum mixture and stir FAST with the stick for about 30 seconds. The mixture should change into a jiggly gel. If it is just right, you can pour it from hand to hand without leaving much water in your hands. If it is not stiff enough, let it sit for a few minutes. The flubber can be kept for a few weeks if refrigerated in a zipper storage bag. What did you observe? The Flubber has some properties of a solid and some properties of a liquid. What properties did you observe in the Flubber? How far can you stretch the Flubber before it breaks? Solid Liquid Where’s the chemistry? Guar gum is made from guar beans grown in India and Pakistan. It is a complex carbohydrate made of long, wiggly strings of simple sugars (galactose and mannose). When borax is added to a mixture of water and guar gum, the borax grabs onto different parts of the long strings, making a gel-like blob that traps water molecules in the network. SAFETY! Procedures: Borax is mildly irritating. Eye protection is necessary. Use of rubber gloves is suggested. 1. M ake some saturated borax solution by stirring powdered borax into a few teaspoons of water until no more dissolves, and let any extra solid settle to the bottom of the container. 2. In a separate cup, mix the water and guar gum with a craft stick for about a minute. Add a drop or two of food coloring and stir. Stir until the mixture is smooth and without lumps. Try this.... Make the glue-based version of Flubber. The recipe is found on page 6 of the NCW 2008 Edition of Celebrating Chemistry, http://issuu.com/kate1dc/docs/ncw_2008_celebrating_ chemistry?viewMode=magazine&mode=embed. Make both and compare the properties! This activity was adapted from WonderScience, American Chemical Society, 2001. Marilyn Duerst is on the Chemistry Faculty of the University of Wisconsin–River Falls and has been active in outreach for more than three decades.