Guar gum is a powder derived from a bean found mostly in India. It is an excellent thickener, eight times better than corn starch and is found in many products from ketchup to ice cream. It is also used as anemulsifier, meaning it keeps oil particles from separating out of water-based solutions, and as a stabilizer, meaning that it keeps solid particles from settling out. These properties derive from the fact that the molecules that make up guar gum are extremely long, so they easily intertwine around themselves to increase the viscosity, or “thickness,” of liquids. We talked about that WAY back in “A Slime By Any Other Name.”
But, here’s the cool thing: when a binding agent, like borax, is added to guar gum in solution, it will bind to itself, trapping liquids between the long molecules. This is called cross-linking and is the key to making great, gelatinous slime!
What You Need:
Guar gum powder (you can purchase this online through many educational science products companies like Flinn, Science Kit, Ward’s, and Carolina Biological or in some health food stores)
Borax (sold as 20 Mule Team on the laundry aisle at your local grocery store)
Food scale/balance (in grams)
Food coloring or any water-based coloring (green is my favorite, but any color will work)
What To Do:
Measure 1 gram of borax
Add the borax to 5 teaspoons of hot water. Stir thoroughly.
Measure 2.5 grams of guar gum
Pour 2 cups + 2 tablespoons of hot water (distilled is best) into a bowl
SLOWLY add in the powered guar gum over about 5 minutes while stirring constantly. CAUTION – If you dump all of it in, it will clump together and you won’t get your slime!
Add in your coloring
Dump in the borax while stirring constantly
Congratulations! You made a colloid! A colloid is when one substance is distributed evenly throughout another substance, but they aren’t dissolved or chemically combined. In this case, the borax reacts with the guar gum to create a mesh of molecules that trap the water and coloring throughout it, creating a gel! A gel is one type of colloid. Other examples include alloys (like stainless steel), aerosols, and foams.