#102 — Elephant Toothpaste

Hydrogen peroxide meets a catalyst and erupts into a 10-foot tower of steaming foam.

Ratings

🧪 What Is It?

Hydrogen peroxide naturally decomposes into water and oxygen gas, but it does it slowly — a bottle of the stuff lasts months in your medicine cabinet. Add potassium iodide as a catalyst and dish soap as a foaming agent, and the decomposition happens all at once. The oxygen gas inflates the soap into a massive column of warm foam that erupts out of whatever container you use. With 12% salon-grade peroxide in a narrow-necked bottle, you can get eruptions over 10 feet tall. It's exothermic (the foam is warm to the touch), completely non-toxic, and the single most reliable crowd-pleaser in all of kitchen chemistry.

🔨 Build Steps

1. Set up the mess zone. Lay a tarp on the ground outdoors or in a garage. The foam expands rapidly and goes everywhere. This is not an indoor-on-the-kitchen-counter experiment. Place your bottle in the center of the tarp.
2. Prepare the bottle. Pour 1 cup (240 mL) of 12% hydrogen peroxide into the bottle. Add a generous squirt of dish soap — about 2 tablespoons. Add food coloring if desired. For a striped effect, drizzle different colors down the inside walls of the bottle before adding peroxide.
3. Mix the catalyst. In a separate small cup, dissolve 1 tablespoon of potassium iodide in 3 tablespoons of warm water. Stir until dissolved. This is your trigger solution.
4. Clear the blast zone. Make sure nobody is standing directly over the bottle. The eruption is fast and tall. Goggles on. Gloves on.
5. Pour the catalyst in one motion. Dump the entire potassium iodide solution into the bottle quickly and step back. The reaction starts within 1-2 seconds.
6. Watch the eruption. Foam rockets out of the bottle and keeps going. A narrow-necked bottle focuses the stream upward. A wide container creates a spreading blob. The foam is warm (exothermic reaction) and safe to touch.
7. Scale it up. For truly massive eruptions, use a 5-gallon bucket, a full liter of 30% peroxide (industrial grade), and proportionally more catalyst. This is how the viral YouTube videos get 30+ foot columns.
8. Clean up. The foam is just soapy water with dissolved iodide. Hose it off the tarp. It's safe for grass and drains.

⚠️ Safety Notes

• Hydrogen peroxide above 12% can cause chemical burns on skin and will bleach clothing on contact. Wear gloves and goggles. If it contacts skin, flush immediately with water.
• The reaction is exothermic — the foam comes out warm, around 100-130°F. Not dangerous but surprising if you stick your hand in the column mid-eruption.
• Never seal hydrogen peroxide in a closed container. Decomposition produces oxygen gas, and a sealed container becomes a pressure bomb.

🔗 See Also

• Dry Ice Bubble Cauldron
• Chemiluminescent Fountain