Erupting jack-o-lanterns

Halloween is a time of slime, with (mildly) gory costumes and pumpkin guts. My boys and I were able to extend the gross fun a little bit more with two versions of erupting jack-o-lanterns that my first-grader liked so much he did a demonstration of one for his 4-H group this month.

His goal: to get as much bubbly goop to burst forth from the pumpkin’s whole face as possible. To try to maximize the amount of substance erupting from the jack-o-lantern’s face, Hunter selected a small pumpkin from our local pumpkin patch, Harvest Specialties.

*Note: Make sure to place your pumpkin in a place in which the foam and liquid will be cleaned up easily. We have used the sink, bathtub and a clear Rubbermaid box. Also be careful not to get the substances in your mouth or eyes.*

His first method of eruption, baking soda and vinegar, we have used before for science experiments, so he was familiar with the method and the outcome, and we used larger amounts of the ingredients to try to make a dramatic eruption. He measured and poured 1/4 c. baking soda, added 10 drops of food coloring, and then poured vinegar into the pumpkin freely to try to get the best result. The foam did not erupt from the whole face as my first-grader had wanted, but there was a great gush out of the mouth. The foam liquefies as it sits.


For his other method of eruption, my first-grader agreed to try Elephant’s Toothpaste, after seeing an example of it on Science Bob’s website. He first mixed 1/2 cup hydrogen peroxide (Science Bob calls for 6% peroxide, available at beauty supply stores), 1 Tbsp. liquid dish soap, and 10 drops of food color in a cup. Then in a second cup, he combined 3 Tbsp. warm water with one packet of dry yeast, mixing for 30 seconds. He poured the peroxide/soap mixture into the jack-o-lantern, then the yeast mixture and watched the magic happen. The foam stays quite foamy after it erupts. At, you can find more details, as well as ways to make it a science experiment, instead of just a fun demonstration.


And now, we get to enjoy the jack-o-lantern as a science experiment.



One thought on “Erupting jack-o-lanterns

  1. Pingback: Halloween Festivities Part 1 | Caution: Boys at Play

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