How-To: Make Soap Foam

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By Gareth Branwyn
Posted 2012/12/22 @ 10:30 am
Category Science, Kids & Family

By way of the World’s Coolest Things’ Facebook page comes this “I HAVE to try this” microwave trick. Apparently, this is what happens when you microwave a bar of Ivory soap. It expands in a foam up to six times its original size. Not sure why it has to be Ivory.

Ivory Soap Trick

BY Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of a dozen books on technology, DIY, and geek culture, including the first book about the web (Mosaic Quick Tour) and the Absolute Beginner's Guide to Building Robots. He is currently working on a best-of collection of his writing, called Borg Like Me.

In the Maker Shed

12 Responses to How-To: Make Soap Foam

Blaise Pascal on December 22nd, 2012 at 10:43 am said:

Dove has 1/4 cleansing cream, not Ivory.

Ivory soap has two claims to fame: it was tested and found to be 99.44% pure soap; and it floats rather than sinks in water. It was originally made accidentally when someone left a soap mixing machine run overnight. The resulting batch was pure white in color and floated because of all the entrained air.

That’s why it foams: the soap heats and softens, and the air bubbles heat and expand, when it cools, the soap hardens again and the air bubbles don’t collapse.

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- Gareth Branwyn on December 22nd, 2012 at 1:11 pm said:
  
  Oops. You’re right. That’s Dove. And just what IS “cleansing cream?”
  
  (I removed that reference.)
  
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trkemp on December 22nd, 2012 at 11:10 am said:

My son tried this with Irish Spring. The stench made us leave the house for several hours and we had to get a new microwave because the smell never left it. In addition it hardly foamed up at all.

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- jstults on December 23rd, 2012 at 5:46 am said:
  
  Ha! We tried Irish Spring too; it was terrible!
  
  To get rid of the smell, and make the microwave suitable for food again we did several cycles of “steam cleaning”: nuke a cup of water for several minutes. The steam and water that gets splashed all over when it boils does a good job of loosening up any bits of soap that got thrown about.
  
  We also tried the Ivory: much better, just grows, doesn’t explode, and doesn’t smell awful.
  
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Raven on December 22nd, 2012 at 2:08 pm said:

Awesome! I just did this with my kids. It smelled some, but hopefully it goes away…

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- Gareth Branwyn on December 22nd, 2012 at 4:34 pm said:
  
  How much volume did you get? I’m anxious to try this myself. Have to go get some Ivory soap.
  
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- Gareth Branwyn on December 22nd, 2012 at 4:37 pm said:
  
  Whoa. I just watched your video, Raven. That is SO cool. Definitely want to try this.
  
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  Raven on December 22nd, 2012 at 6:15 pm said:
  
  It was sooo cool. I didn’t leave it in the recommended length of time (90 – 120 secs), so there is some bar left in the middle. And the smell is gone now, I can imagine how much Irish spring would reek. I can’t stand the smell of it. ~~~
  
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Pingback: Microwaving Ivory Soap « Raven Lunatick
yahoo on December 22nd, 2012 at 4:45 pm said:

yup works on tesco value soap too. worked that out trying to melt and pour. oh and don’t leave it in too long or it starts burning an that really doesn’t smell good

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t-bird on December 22nd, 2012 at 11:05 pm said:

I wonder if you can expand it into molds, like a giant rubber ducky or something

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Stevan Farkas on December 25th, 2012 at 2:56 pm said:

from the source article; Cut or break off a piece of Ivory™ and examine it. Do you see pockets of air? The air that causes Ivory™ to be less dense than water has been whipped into the soap, so you won’t see bubbles or pockets of air. This is important, because it’s the reason why the soap trick works.

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