The well-stocked back-to-school section in most stores means one thing to most kids: The Elmer's glue shortage is officially over!
In 2016, school glue became a hot commodity when the "slime" craze hit classrooms across the U.S. With a simple mixture of glue, water, and a few other ingredients, kids can create a textured blob that's fun to knead, stretch, mold, and shape. Adding glitter, dye, and scented oils allows crafters to customize the sensory stuff to their liking, but that's just the beginning: Other additives can make slime magnetic, glow-in-the-dark, heat-responsive, and more.
But there's more to slime than glitter and eye-popping colors; there's a surprising amount of science behind the stuff. For starters, the substance is a non-Newtonian fluid, a liquid that doesn't conform to "normal" models of viscosity, meaning that its viscosity is affected by not temperature but force or stress. Making slime is a fantastic way for kids to experiment with the way non-Newtonian fluids act.
Then there's the science of how the glue reacts with other ingredients. Glue is a type of polymer, made of long chains of polyvinyl acetate molecules, which slide around and allow the glue to be squeezed out of the bottle. Adding Borax—also known as sodium borate or sodium tetraborate—to the mix results in cross-linking between the glue's protein molecules and the borate ions. The reaction links large molecules together, creating even bigger molecules that prevents them from sliding as easily and creates the slime texture. [PDF]
Though most of the original recipes included Borax, which is primarily used as a cleaning agent, reports quickly surfaced of kids suffering from serious chemical burns after submerging their hands in the substance for too long.
To avoid any mishaps, we've rounded up three of the best basic slime recipes that don't require the use of Borax. Grab the Elmer's while it's still on the shelves, and put a couple of these slime recipes to the test.
CONTACT LENS SOLUTION SLIME
After conducting their own tests to determine a safe way to create slime, Elmer's came up with a concoction that uses contact lens solution.
First, mix together 4 ounces of Elmer's white school glue with a 1/2 tablespoon of baking powder and a 1/2 tablespoon of baking soda. Knead the slime until you get your desired viscosity, adding drops of contact lens solution until you're happy with the result. Add dye, glitter, or other additives as desired.
For slime that's less ooey-gooey and more fluffy-puffy, try a combination of a 1/2 cup of shampoo and a 1/4 cup of cornstarch. Add 1 tablespoon of water and stir. Mix in 5 more tablespoons of water, one tablespoon at a time, stirring well after each addition. If your slime is too sticky, knead in more cornstarch until you get it to a dough-like consistency.
SHAVING CREAM SLIME
Using shaving cream will give this version an extra fluffy feel. Mix a tablespoon of baking soda with just enough contact lens solution to cover it. Mix until combined. In a separate bowl, fold together a 1/2 cup of glue with a 1/2 cup of shaving cream. If you want colorful slime, add food coloring before folding. Add the baking soda solution and mix until putty-like. Knead the slime for about three minutes, then place in a sealed container. It should be ready to play with in an hour or two.