Expanding foam- Fast extending foam

Make fast coloured expanding foam

Make fast expanding foam coloured with different colours you want! Some people called it also elephant toothpaste because it looks like the toothpaste an elephant might use.

Here’s how to set up this demonstration and a look at the reaction behind it.

Expanding foam materials

  • 50-100 ml of 30% hydrogen peroxide (H2O2) solution
  • saturated potassium iodide (KI) solution
  • liquid dishwashing detergent
  • food coloring
  • 500 mL graduated cylinder
  • splint (optional)


Wear disposable gloves and safety glasses. Oxygen is evolved in this reaction, so do not perform this demonstration near an open flame. Also, the reaction is exothermic, producing a fair amount of heat, so do not lean over the graduated cylinder when the solutions are mixed. Leave your gloves on following the demonstration to aid with clean-up. The solution and foam may be rinsed down the drain with water.

Procedure of makeing Expanding Foam

  1. Put on gloves and safety glasses. The iodine from the reaction may stain surfaces so you might want to cover your workspace with an open garbage bag or a layer of paper towels.
  2. Pour ~50 mL of 30% hydrogen peroxide solution into the graduated cylinder.
  3. Squirt in a little dishwashing detergent and swirl it around.
  4. You can place 5-10 drops of food colouring along the wall of the cylinder to make the expanding foam resemble striped.
  5. Add ~10 mL of potassium iodide solution.
  6. You may touch a glowing splint to the foam to relight it, indicating the presence of oxygen.

What is going on in expanding foam?

The dishwashing detergent captures the oxygen as bubbles. Food colouring can colour the foam. The heat from this exothermic reaction is such that the foam may steam. If the demonstration is performed using a plastic bottle, you can expect slight distortion of the bottle from the heat.



Expanding foam- Fast extending foam on 2015-07-15 rated 4.9 of 5

One Response

  1. CoolExperiments 3 years ago

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