Take a holiday from “serious” science and have fun with these slime recipes. Plus see the amazing properties of Thinking Putty in our Thinking Putty video.

Making slime has long been a favorite chemistry activity. Who doesn’t like to play with something gooey and squishy and, well, slimy, every once in awhile? This issue will show you how to make slime with household ingredients, or how to step it up a notch with a liquid polymer called polyvinyl alcohol.

Homemade Slime

Oozing slimeThis is a fun and easy slime to make. Make it with white glue for opaque slime, or glue gel for translucent slime.

What You Need:

  • Elmer’s white glue or Elmer’s school glue gel
  • Borax (find in the laundry detergent aisle of the store)
  • Water
  • Two bowls
  • Food coloring (optional)

What You Do:

  1. In one bowl mix 1/2 cup (4 oz) glue and 1/2 cup water. Add food coloring if you want colored slime.
  2. In the other bowl, mix 1 teaspoon borax with 1 cup water until the borax is dissolved.
  3. Add the glue mixture to the borax solution, stirring slowly.
  4. The slime will begin to form immediately; stir as much as you can, then dig in and knead it with your hands until it gets less sticky. (No one makes slime without getting a little messy!) Don’t worry about any leftover water in the bowl; just pour it out.

What Happened:

The glue has an ingredient called polyvinyl acetate, which is a liquid polymer. The borax links the polyvinyl acetate molecules to each other, creating one large, flexible polymer. This kind of slime will get stiffer and more like putty the more you play with it.

Store it in a plastic bag in the fridge, to keep it from growing mold.

Super Slime

This slime is similar to the one above, but creates a less rubbery and more transparent slime. This is the real gooey deal! (This slime is non-toxic, but still keep these chemicals away from unsupervised children and wash your hands after playing with the slime.)

What You Need:

What You Do:

  1. Make a 4% solution of polyvinyl alcohol: Stir 1.5 teaspoons (approx. 4g) of PVA into 1/2 cup (approx 100 ml) of water in a large microwave-safe bowl. Cover the bowl and microwave for 1 minute, then stir. Microwave another 30 seconds and stir. Continue until all the PVA is dissolved. A slight film may have formed on top; you can remove that with a spoon. You can add food coloring if you want colored slime. Allow the solution to cool.
  2. Make a 4% borax solution by stirring a little less than 2 teaspoons (approx. 4g) of Borax into 1/2 cup of water.
  3. Pour the cooled PVA solution into a ziplock bag and add 2 teaspoons (10ml) of the borax solution.
  4. Zip the bag and knead it until the chemicals are mixed into slime. Then scoop it out and play with it.

What Happened:

While water is a liquid made up of individual H2O molecules, polyvinyl alcohol is formed of long chains of connected molecules, making it a liquid polymer. (The term polymer comes from the words for “many parts.”) The borax acts as a “cross-linker,” linking the individual PVA chains to each other so they connect to form a blob of slime. It does this linking job when the borax molecules form hydrogen bonds with molecules present in the PVA chains. (The partial positive charge of hydrogen atoms attracts the partial negative charge of oxygen atoms.) Since hydrogen bonds are weak, they can break and reform as you play with the slime or let it ooze on a flat surface.

Your slime will last for a while if you seal it in a plastic bag and keep it in the fridge.

Other fun home recipes:

Fun with Thinking Putty

Everyone loves playing with a little silly putty, but Thinking Putty is even better! It’s the ultimate putty that can stretch, squish, tear, smash, bounce, make noise, and change color.

Thinking Putty videoEven if you don’t have some, you can see it in action with our Thinking Putty video.

Putty is a Non-Newtonian substance, which means that it doesn’t follow the theory of viscosity that Newton observed. Viscosity is the “thickness” of a liquid, or its resistance to flow. (Honey, for example, has a much higher viscosity than water.) Thinking Putty, while sometimes having properties of a high-viscosity liquid, also has certain properties of a solid. Like a liquid, it won’t hold its shape, although because of its high viscosity, it moves very slowly. Unlike most liquids, however, Thinking Putty changes its behavior based on the amount of force applied. If you pull it gently, it will stretch; if you pull it forcefully, it will tear. If you push your finger in gently it will sink deep into the putty, but if you jab it hard your finger will bounce right off. When you apply the ultimate force—hitting it with a hammer—it acts exactly like a solid and shatters as though it were ceramic. (But then you can pick up the pieces and stretch and smash them like putty again!)

Stretching, Tearing, and Popping:

One of the most fun things to do with putty is just to stretch, twist, squish, and mold it into shapes. While you’re at it, you can make a little noise.

  1. Stretch your putty out into a thin sheet. Fold it over once, then again  the opposite way. Keep folding until you can’t fold any more. When its all folded up, squeeze it to hear it pop!  When you stretched and folded, you trapped air bubbles in the putty. Experiment with ways to get even bigger air bubbles trapped to make more noise.
  2. You’ve seen how putty stretches out when you pull it gently. This makes it hard to break off a piece; it just keeps stretching out. Because it’s a Non-Newtonian substance, though, Thinking Putty will act like a solid if you apply enough force. Pinch the putty at an edge and then quickly tear it across, just like you would tear a piece of paper. If you use enough force, it will tear into two pieces cleanly, instead of stretching.

Changing Color:

Some Thinking Putty is thermo-chromatic, meaning that it changes color with changes in temperature! Just playing with the putty in your hands will warm it up enough to change colors, but you can also use a hairdryer to change its color in quick, dramatic fashion. Then use something cold, like ice or compressed air, to “draw” on your warm putty. If you just stick a piece of ice onto the putty, you’ll see the cold color “glow” through the ice cube.

Bouncing & Smashing:

  1. Roll your putty into a ball and drop it on the counter or floor—it will bounce like a rubber ball!
  2. It bounces, but it also shatters! You may want to do this part outside so you don’t make a mess. Your putty will get a little dirty, so just use a small part of it. Put a ball of putty on a concrete or cement surface, hit it forcefully with a hammer, and watch it shatter. Wear safety glasses to protect your eyes from flying pieces of putty.

These are just a few activities with Thinking Putty – experiment to find more fun things to do with it! You can also get magnetic or glow-in-the-dark varieties.