How to make slime
Quick answer
Mix ½ cup (120 ml) of PVA school glue with ½ tablespoon of baking soda, add food coloring if you like, then stir in 1 tablespoon of contact lens solution that contains boric acid. Knead until it stops sticking, adding a few more drops of solution if needed.
Step by step
- Pour the glueAdd ½ cup (120 ml) of white or clear PVA school glue to a bowl.
- Add baking sodaStir in ½ tablespoon of baking soda until it dissolves. Add a few drops of food coloring or some glitter now if you want.
- Add the activatorPour in 1 tablespoon of contact lens solution and stir. The mixture will start pulling away from the sides of the bowl.
- Knead itOnce it forms a blob, pick it up and knead it with your hands for a minute or two. It gets less sticky as you work it.
- AdjustStill sticky? Add a few more drops of contact solution and knead again. Go slowly, because too much makes it stiff and rubbery.
Slime is a little bit of chemistry you can hold. The glue contains long, stringy molecules called PVA (polyvinyl acetate). The borate in the contact solution links those strings together into a stretchy net, turning a liquid into something that oozes and snaps.
Check your contact lens solution
This recipe only works if the solution lists boric acid and sodium borate in its ingredients. Many popular brands do, but saline-only solutions won’t activate the glue at all.
How to fix slime that isn’t right
| Problem | Fix |
|---|---|
| Too sticky | Add a few more drops of contact solution and knead |
| Too stiff or rubbery | Knead in a little warm water or hand lotion |
| Won’t come together | The solution probably has no boric acid; try another brand |
| Dried out after a few days | Knead in a few drops of warm water |
Safety tips
- Adults should supervise younger children, and slime isn’t suitable for kids who still put things in their mouths.
- Don’t eat it, and wash hands before and after playing.
- Stop if hands get red or itchy, as borates can irritate sensitive skin.
- Keep slime off carpets, clothes and furniture; white vinegar helps loosen it if it sticks.
Not sure about the amounts? Half a US cup is 4 fluid ounces; here’s how many ounces are in a cup for other conversions.
Store slime in an airtight container or zip bag. It usually stays fresh for about a week before it starts to dry out.
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