Recipe · No glue
No-glue slime: cornstarch oobleck (2 ingredients)
A slime with no glue and no activator, made with cornstarch and water: hard when you tap it, runny when you stroke it. Ratios, steps, and the science behind it.
- DifficultyVery easy
- Time5 minutes
- Makes1 bowl
- Recommended ageAges 3+, with an adult
This is the simplest and most surprising slime of all: just cornstarch and water. No glue, no contact lens solution, so no boron at all. Most people know it as “oobleck.”
It isn’t a slime that stretches: it’s a mixture that turns hard like a solid when you tap or squeeze it, then runs through your fingers as soon as you let go. Kids love it, and it’s a real science experiment.
Ingredients
- 2 parts cornstarch (for example, ¾ cup plus 1 tbsp: about 200 ml, or 130 g)
- 1 part water (about 7 tbsp, or 100 ml)
- A few drops of food coloring (optional)
Supplies: a fairly wide mixing bowl, a spoon, a tray or a wipeable tablecloth.
Steps
- Pour the cornstarch into the bowl.
- Add the food coloring to the water, then pour the water in a little at a time, mixing with your fingers.
- Stop adding water when the mixture flows slowly but turns hard if you tap it with the spoon.
- Play: squeeze it into a ball, then open your hand and watch it melt.
How do you know it worked?
The test: tap the surface quickly with your finger, and it should push back like a solid; press your finger in slowly, and it should sink in like a liquid. Too runny? Add a spoonful of cornstarch. Too dry and crumbly? A spoonful of water.
The most common slime fails
- It’s completely runny
- Too much water: add cornstarch a spoonful at a time.
- It crumbles
- Not enough water: add 1 tbsp at a time.
- It dried out in the bowl
- That’s normal: the water evaporates. Add a little water and stir, and it comes right back.
Why does it work?
Cornstarch doesn’t dissolve in water: it’s made of tiny grains floating in it. If you push gently, the water lets them slide past each other. If you hit it, the grains jam together and the mixture acts like a solid. This is what’s called a non-Newtonian fluid.
Variations and ideas
- For a slime that really stretches, you need a binder: try the edible marshmallow slime, which is also glue-free.
- Everything about borax-free and boron-free recipes: the borax-free slime guide.
How to store it
This slime doesn’t keep: it dries out or gets moldy within a day or two. Make it right when you want to play, then throw it in the trash afterward.
✅ I made it! Add it to my logbook
Try these too
All recipesIngredients explainedBorax-Free Slime: The Truth About Contact SolutionSlime Birthday Party: The Game Plan for 8 Kids