Monday, March 15, 2010

Ivory soap experiment

This was not Ivory didn't float or foam in the microwave

Making bunny soap
This was Kenzie's soap turtle

Kylan just liked creating with it
Ivory soap in the microwave

Yes, it does float!

How long with math cubes

5 orange potatoes has some great science experiments and my kids have loved all of them so far. They loved this one too and she even has a down loadable booklet to use! It's so fun to watch the soap in the microwave as it grows and grows, make sure it place in the exact middle of your plate or it will go over the sides.


1. Place the bar of Ivory soap in the middle of a microwave safe plate. Place the whole thing in the center of the microwave oven.

2. Cook the bar of soap on HIGH for 2 minutes. Don't take your eyes off the bar of soap as it begins to expand and erupt into beautiful puffy clouds.

3. Allow the soap to cool for a minute or so before touching it. Amazing... it's puffy but rigid.

Why this happens

Ivory soap is one of the few brands of bar soap that floats in water. If it floats in water, it must mean that it's less dense than water. When you broke the bar of soap into several pieces, no large pockets of air were discovered. Ivory soap floats because it has air pumped into it during the manufacturing process. The air-filled soap was actually discovered by accident in 1890 by an employee at Proctor and Gamble. While mixing up a batch of soap, the employee forgot to turn off his mixing machine before taking his lunch break. This caused so much air to be whipped into the soap that the bars floated in water. The response by the public was so favorable that Proctor and Gamble continued to whip air into the soap and capitalized on the mistake by marketing their new creation as The Soap that Floats! Why does the soap expand in the microwave? This is actually very similar to what happens when popcorn pops. Here's the secret: All soap contains water, both in the form of water vapor inside trapped air bubbles (particularly important in the case of Ivory) and water that is caught up in the matrix of the soap itself. The expanding effect is caused by the heating of the water that is inside the soap. The water vaporizes, forming bubbles, and the heat also causes trapped air to expand. Likewise, the heat causes the soap itself to soften and become pliable. This effect is actually a demonstration of Charles' Law. When the soap is heated, the molecules of air in the soap move faster causing them to move far away from each other. This causes the soap to puff up and expand to an enormous size. Charles' Law states that as the temperature of a gas increases so does its volume. Other brands of soap without whipped air tend to heat up and melt in the microwave.

When you are finished let the kids play with the puffy soap and create with it. Makenzie made a turtle with hers and Kylan just liked the texture and feel of it. When we were finished we put the soap in pan and added some crushed oatmeal and some crushed lavender to our soap and put 1 tsp of water at a time into the soap mixture until it was the consistency that we wanted then we poured it into a bunny mold for Easter. The kids are so excited to use this soap!

We found many other links on the web for the Ivory soap experiment too and here are a few of them Steve Spangler's Soap Souffle, Wiki- How to Expand Ivory Soap, You Tube demos, Your fun family, and
Let me know if you do this experiment and how it turns out for your family!


LJ said...

OK, you are just too creative! I'll have to let my kiddos do this experiment with the soap.

Jennifer said...

I wish I had a bar of Ivory right now. We will be trying this. Thanks for sharing!

The Flirtation Experiment-book review and giveaway

About the authors:  Lisa Jacobson  is an author, a podcaster, and the founder of, an online community of Christian women aut...