Steve Spangler Science

Using a Purchase Order?  •  Back to School  •  Spangler Science Club

Questions? Give us a Call: 1-800-223-9080

Oozing Pumpkins - Sick Science!

A new experiment to add a fun twist to your jack-o-lantern

Rating: 43211

Submit A Review

It's an awesome new Halloween twist on our Kid-Friendly Elephant's Toothpaste experiment! With this demonstration, you'll have an awesome foaming ooze seeping from the face of your jack-o-lantern and squeals of excitement coming from the face of your audience.

  • Hydrogen peroxide - 12% (You can find this in the hair care section.)
  • Liquid dish soap
  • Food coloring
  • Package of dry yeast
  • Small cup (make sure it's small enough to fit all the way in your pumpkin)
  • Don't forget... a small carved pumpkin
Print Experiment


  1. Fill a small cup with 30 mL of hydrogen peroxide (12%).
  2. Add a squirt of dish soap to your hydrogen peroxide.
  3. Mix in some some food coloring to give your reaction a bit of effect.
  4. Open up the top of your jack-o-lantern and carefully lower the cup of mixture into the jack-o-lantern. Don't tip it over or you'll have to start over from the beginning.
  5. Now you're going to need to create your Elephant's Toothpaste catalyst. Mix an entire package of dry yeast with 4 tablespoons of very warm water in a small plastic cup. If the mixture is too thick, like a paste, add a little more warm water to thin it out.
  6. Pour the yeast solution into the cup and quickly replace the top of your jack-o-lantern. It may take a few seconds, but once the reaction starts the result is well worth the wait.

How Does It Work?

In this reaction, you've got a catalyst in the form of your yeast solution. This catalysts works to release the oxygen molecules that are contained in the hydrogen peroxide. Those molecules are being released as the hydrogen peroxide breaks down into two components, water (H2O) and oxygen (O2), from the addition of the yeast catalyst. The foam is the molecules of oxygen being made into tiny bubbles as they pass through the soap that your added.  In addition, as the bonds break between the H2O and O2, they release energy in the form of heat. Try performing the experiment without the pumpkin and feel the sides of the cup. They're warm!

Customer Reviews

Wear Gloves! Review by Linda Brzezinski

In the other elephant toothpaste experiment, you said 20 volume was 6%. So doesn't that mean 12% is 40 volume? You can get that at Sally's Beauty Supply, but USE GLOVES and don't let kids touch it! I've also found lots of variation with the yeast. Active dry works better than rapid rise, and foil packet must be freshly opened. Test it ahead if you don't want a disappointment.

(Posted on November 25, 2011)

Great use for leftover pumpkins! Review by Diana

Did this today with my 4th and 5th graders in science club. One pumpkin worked well, the other didn't have enough "ooze". The only thing I had trouble with was finding the peroxide!! Could not find 12% at all. A parent found a solution from a hair place that worked well, but it was hard to find! Any ideas where you can find the 12% peroxide more easily?

(Posted on November 2, 2011)

The peroxide Review by Lynette

40V Developer at a beauty supply store is 12%. Brands might be Clairoxide or Ms Kay, but make sure you get clear and not creme.

(Posted on October 27, 2012)

Write Your Own Review

You're reviewing: Oozing Pumpkins - Sick Science!

How do you rate this experiment? *
1 star 2 stars 3 stars 4 stars 5 stars