How to Make Oobleck
Mix cornstarch and water to create oobleck, a fascinating non-Newtonian fluid that acts as a solid when squeezed and melts like liquid when released.
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🧰 Required Tools & Equipment
- ✓ Large mixing bowl
- ✓ 1-cup dry measuring cup
- ✓ Liquid measuring cup
- ✓ Sturdy mixing spoon or spatula
- ✓ Rimmed plastic tray or baking sheet
📦 Materials & Supplies
- ✓ 2 cups cornstarch
- ✓ 1 cup lukewarm water
- ✓ Liquid food coloring (optional, 3-5 drops)
⚠️ Safety Checkpoints & Warnings
- • Never pour oobleck down the sink drain, as the settled starch quickly hardens and causes severe plumbing clogs.
- • Measure cornstarch slowly and close to the bowl to prevent kicking up airborne dust that can irritate airways.
- • Food coloring can stain porous surfaces, clothing, and skin; cover your workspace with a wipeable mat or newspaper.
📋 Step-by-Step Guide (6 Steps)
Prepare the Work Area and Measure Cornstarch
Wipe down a flat surface and lay out a rimmed tray or protective plastic tablecloth. Measure exactly 2 cups of dry cornstarch using a dry measuring cup, leveling the top gently. Slowly pour the cornstarch into your large mixing bowl without shaking the cup vigorously to minimize dust.
- • Two level cups of cornstarch rest smoothly at the bottom of the bowl
- • Minimal airborne white dust around the workstation
- • Dumping the cornstarch quickly, which creates an irritating cloud of fine powder
Measure and Color the Water
Fill a liquid measuring cup with 1 cup of lukewarm water. Add 3 to 5 drops of your chosen food coloring directly into the water and stir thoroughly with a spoon. Pre-coloring the water ensures the tint disperses evenly through the cornstarch without streaking.
- • Water is uniformly tinted with vibrant color with no concentrated dye beads
- • Adding food coloring directly to dry cornstarch, which creates concentrated splotches that are difficult to blend
Gradually Pour Water into the Cornstarch
Pour roughly half of the colored water (about 1/2 cup) into the center of the cornstarch bowl. Use a sturdy spoon to stir in slow, circular motions, pulling dry starch from the edges into the liquid center. The mixture will begin to feel stiff and resistant almost immediately.
- • A thick, chalky paste forms in the center while loose powder remains on the sides
- • Pouring all the water in at once, which makes it easy to overshoot the ideal consistency
Incorporate Remaining Water and Knead by Hand
Add the remaining water 1 to 2 tablespoons at a time, setting the spoon aside and using your bare hands to blend. Squeeze the clumps between your fingers and scrape the bottom of the bowl until all dry powder is fully hydrated. The mixture should feel solid when squeezed firmly, but liquefy the moment you open your palm.
- • No dry, powdery patches remain anywhere in the bowl
- • Mixture behaves as a firm mass when squeezed but flows smoothly through fingers when released
- • Adding extra water too quickly when the mixture feels tough, resulting in a runny liquid instead of oobleck
Transfer and Test Fluid Properties
Pour the finished oobleck onto a flat, rimmed tray or baking sheet for open play and testing. Tap the surface rapidly with an open palm or knuckle to observe it act like a firm solid, then gently sink your fingers slowly into the pool to feel it behave like liquid. Roll a handful rapidly into a solid ball, then stop moving your hands to watch it melt back into a puddle.
- • Surface resists rapid slapping without splashing
- • Oobleck melts entirely into a flat puddle within seconds of stopping movement
- • Assuming the recipe failed because it feels hard during fast movements; high shear resistance is the correct behavior
Clean Up and Dispose of Oobleck
Scrape excess oobleck from the tray and hands directly into a plastic trash bag or compost bin using a spatula. For any residue left on hands or bowls, wipe thoroughly with dry paper towels first before rinsing with warm, running water. Allow any small remaining film in the bowl to dissolve under heavy running hot water.
- • All bulk oobleck is secured inside the trash receptacle
- • Surfaces and tools are wiped clean without thick starch deposits entering the sink drain
- • Washing large quantities of oobleck down the drain, which settles into a hard plug in the plumbing trap
Credit: inspired by an original tutorial by Ryan's World — watch the original on YouTube.
Don’t have everything?
- No Cornstarch? Arrowroot starch, tapioca starch, or potato starch
- No Food coloring? A few drops of washable tempera paint or turmeric powder for yellow tint