Oobleck is one of the coolest science-meets-sensory activities for kids. It feels solid when you squeeze it and turns liquid when you let it go. But what if you’re out of cornstarch?
Good news: you can still make a similar non-Newtonian, squishy mixture using common pantry substitutes.
This video shows two ways to make Oobleck without cornstarch:
Let’s walk through how to make oobleck without cornstarch — step by step.
What Is Oobleck?
Oobleck is a non-Newtonian fluid. That means it doesn’t behave like a normal liquid.
- Apply pressure → it feels solid.
- Release pressure → it flows like a liquid.
Traditional oobleck uses cornstarch and water. When replacing cornstarch, we use other fine powders that react similarly with water to create that same “solid-when-squeezed” effect.
Is It Safe for Kids?
Yes, the alternatives below are non-toxic when made with food-based ingredients.
Safety tips:
- Supervise young children.
- Do not allow eating large amounts.
- Avoid getting mixture in eyes.
- Wash hands after play.
- Use a tray or plastic mat to control mess.
Now let’s make it.
Best Cornstarch Substitutes for Oobleck
You can use:
- All-purpose flour
- Baking soda
- Arrowroot powder
- Potato starch
Arrowroot and potato starch behave most like cornstarch. Flour works too, but the texture is softer and less dramatic.
Below are the best recipes.
Option 1: How to Make Oobleck Without Cornstarch Using Flour
Ingredients
- 1 cup all-purpose flour
- ½ cup water (adjust slowly)
- Food coloring (optional)
Step-by-Step Instructions
Step 1: Add Flour to a Bowl
Pour 1 cup of flour into a mixing bowl.
Step 2: Add Water Slowly
Add water a little at a time while stirring.
Do not dump it all in at once.
Step 3: Mix and Adjust
Stir until thick. You want it to feel:
- Firm when squeezed
- Loose when released
If too runny → add more flour.
If too thick → add a teaspoon of water.
Step 4: Test the Texture
Punch it quickly. It should resist your hand.
Then slowly lift your fingers — it should drip down.
Note: Flour oobleck is softer than cornstarch oobleck but still fun for sensory play.
Option 2: How to Make Oobleck Without Cornstarch Using Baking Soda
Ingredients
- 1 cup baking soda
- ¼–½ cup water
- Food coloring (optional)
Step-by-Step Instructions
Step 1: Add Baking Soda
Place baking soda in a bowl.
Step 2: Slowly Add Water
Add small amounts while stirring.
Step 3: Adjust Texture
You want a thick, heavy mixture that stiffens when pressed.
Baking soda version is thicker and more moldable.
Option 3: Best Substitute – Arrowroot or Potato Starch
If you have arrowroot or potato starch, this works closest to traditional oobleck.
Ingredients
- 1 cup arrowroot or potato starch
- ½ cup water
Steps
Follow the same process as flour, adding water gradually.
This version gives the most dramatic “solid-liquid” reaction.
How to Make It More Fun
Once you’ve nailed the texture, try:
- Adding food coloring
- Using glitter
- Hiding small toys inside
- Dropping small balls to watch them bounce
- Pressing cookie cutters into it
- Pouring it between containers
For extra science fun, try tapping it quickly versus pressing slowly and observe the difference.
Why Does Oobleck Act This Way?
Oobleck is made of tiny solid particles suspended in water.
When you apply pressure:
- The particles jam together
- The mixture becomes temporarily solid
When you relax pressure:
- The particles slide past each other
- It flows like liquid
This makes it a perfect STEM activity.
How to Store Oobleck
Oobleck doesn’t store well long-term.
Best practice:
- Keep in airtight container
- Stir before reuse
- Add small amounts of water if it dries
If it smells odd or changes texture significantly, discard and make a fresh batch.
Quick Fixes for Common Problems
| Problem | Quick Solution | Pro Tip |
|---|---|---|
| Too watery | Add more flour, baking soda, or starch gradually | Mix slowly to avoid lumps |
| Too stiff | Add water one teaspoon at a time | Small adjustments make big differences |
| Not acting solid | Increase powder ratio slightly | Arrowroot gives strongest reaction |
| Lumpy texture | Stir thoroughly or knead with hands | Add water slowly next time |
| Dries out quickly | Store airtight and add small water before play | Oobleck is best fresh |
Common Mistakes to Avoid
- Adding all the water at once
- Expecting flour version to act exactly like cornstarch
- Using warm water (room temperature works best)
- Leaving it uncovered
Start small. Adjust gradually.
Frequently Asked Questions
Can I use baby powder instead of cornstarch?
No. Baby powder often contains talc and is not safe for this activity.
Is flour oobleck safe to taste?
It’s technically edible, but raw flour shouldn’t be eaten. Supervision is important.
Can I make colored oobleck?
Yes. Add food coloring to the water before mixing.
Why isn’t it as firm as cornstarch oobleck?
Cornstarch creates the strongest non-Newtonian reaction. Arrowroot or potato starch are closer substitutes than flour.
How long does it last?
Best used the same day. It may separate over time but can be remixed briefly.
Final Thoughts
Making oobleck without cornstarch is completely possible using flour, baking soda, arrowroot, or potato starch.
While the reaction may vary slightly, the sensory fun and science experiment excitement remain the same.
Mix slowly. Adjust gradually. Experiment freely.
Then squeeze it, punch it, and watch it flow through your fingers — that’s when the magic happens.
