How-To: Make Soap Foam

How-To: Make Soap Foam


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

24 thoughts on “How-To: Make Soap Foam

  1. Blaise Pascal says:

    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 It was originally made accidentally when someone left a soap mixing machine run overnight.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.

    1. Gareth Branwyn says:

      Oops. You’re right. That’s Dove. And just what IS “cleansing cream?”

      (I removed that reference.)

  2. trkemp says:

    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.

    1. jstults says:

      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.

  3. Raven says:

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

    1. Gareth Branwyn says:

      How much volume did you get? I’m anxious to try this myself. Have to go get some Ivory soap.

    2. Gareth Branwyn says:

      Whoa. I just watched your video, Raven. That is SO cool. Definitely want to try this.

      1. Raven says:

        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. :P~~~

  4. Microwaving Ivory Soap « Raven Lunatick says:

    […] From via Make comes the knowledge that you can microwave Ivory soap, and it will blow up into a huge foamy mass […]

  5. yahoo says:

    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

  6. t-bird says:

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

  7. Stevan Farkas says:

    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.

Comments are closed.

Discuss this article with the rest of the community on our Discord server!

Gareth Branwyn is a freelance writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor to Boing Boing, Wink Books, and Wink Fun. His free weekly-ish maker tips newsletter can be found at

View more articles by Gareth Branwyn


Maker Faire Bay Area 2023 - Mare Island, CA

Escape to an island of imagination + innovation as Maker Faire Bay Area returns for its 15th iteration!

Buy Tickets today! SAVE 15% and lock-in your preferred date(s).