There are lots of recipes for slime. Which one you choose depends on the ingredients you have and the type of slime you want. This is a simple, reliable recipe that produces classic slime.
Store your slime in a zip-lock bag in the fridge to prevent it from developing mold!
What You Need to Make Slime
- Borax powder
- 4 ounce (120 ml) glue (e.g., Elmer's white glue)
- Jar or measuring cup
- Food coloring (optional)
- Measuring cup
How to Make Slime
- Pour the glue into the jar. If you have a big bottle of glue, you want 4 oz or 1/2 cup of glue.
- Fill the empty glue bottle with water and stir it into the glue (or add 1/2 cup of water).
- If desired, add food coloring. Otherwise, the slime will be an opaque white.
- In a separate, mix one cup (240 ml) of water into the bowl and add 1 teaspoon (5 ml) of borax powder.
- Slowly stir the glue mixture into the bowl of borax solution.
- Place the slime that forms into your hands and knead until it feels dry. Don't worry about the excess water remaining in the bowl.
- The more the slime is played with, the firmer and less sticky it will become.
- Have fun!
How Slime Works
Slime is a type of non-Newtonian fluid. In a Newtonian fluid, viscosity (ability to flow) is only affected by temperature. Typically, if you cool a fluid down, it flows more slowly. In a non-Newtonian fluid, other factors besides temperature affect viscosity. Slime viscosity changes according to pressure and shear stress. So, if you squeeze or stir slime, it will flow differently than if you let it slide through your fingers.
Slime is an example of a polymer. The white glue used in the classic slime recipe is also a polymer. The long polyvinyl acetate molecules in glue allow it to flow from the bottle. When polyvinyl acetate reacts with the sodium tetraborate decahydrate in borax, protein molecules in the glue and borate ions form cross-links. The polyvinyl acetate molecules can't slip past each other so readily, forming the goo we know as slime.
Tips for Slime Success
- Use white glue, such as Elmer's brand. You may also make slime using the clear or translucent school glue. If you use white glue, you get opaque slime. If you use a translucent glue, you get translucent slime.
- If you can't find borax, you can substitute contact lens solution for the borax and water solution. Contact lens solution is buffered with sodium borate, so it's basically a pre-made mixture of the key slime ingredients. Don't believe internet tales that "contact solution slime" is borax-free slime! It's not. If borax is a problem, consider making slime using a truly borax-free recipe.
- Don't eat the slime. Although it isn't especially toxic, it is not good for you either! Similarly, don't let your pets eat the slime. While boron in borax isn't considered an essential nutrient for humans, it actually is an important element for plants. Don't feel bad if a bit of slime falls into the garden.
- Slime cleans up easily. Remove dried slime after soaking with water. If you used food coloring, you may need bleach to remove the color.
- Feel free to jazz up the basic slime recipe. The cross-linking that holds the polymer together also helps slime hold mix-ins. Add tiny polystyrene beads to make the slime more like floam. Add pigment powder to add color or to make the slime glow under black light or in the dark. Stir in a bit of glitter. Mix in a few drops of fragrance oil to make the slime smell good. You can add a bit of color theory by dividing the slime into two or more chunks, coloring them differently, and watching how they mix. You can even make magnetic slime by adding some iron oxide powder as an ingredient. (Avoid magnetic slime for very young children, because it contains iron and there's a risk they might eat it.)
- I've got a YouTube video of the slime showing what you will get if you use glue gel rather than white glue. Either type of glue works well.