Ivory Soap Blowup Science Activity & Soap Shapes DIY

Originally I had a different activity planned but it failed miserably. So instead we have finally done the Ivory Soap microwave blowup science experiment to…

Originally I had a different activity planned but it failed miserably. So instead we have finally done the Ivory Soap microwave blowup science experiment to add to this week’s science reactions. Now that it is over I am thinking, why didn’t we do this earlier because that was awesome! I do have a couple words of caution as well as directions on how to make fun soap shapes after the soap has been blown up.

Ivory Soap Blow Up: Make a bar of soap turn into a magical pile of white fluff for a fun science activity with kids.

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I was on the fence about letting Mr. Tickles (age 1.5) do this activity with us because it looked so fun I didn’t want him to be left out, but soap isn’t edible and I didn’t want to break my own rule. We did this activity while he was napping and I was feeling guilty. The guilt went away as I realized this wasn’t a good early toddler activity at all (to see our Toddler Approved Activities click here) because once the soap had been heated in the microwave it was really fluffy and caused a lot of soap dust in the air. If Mr. Tickles would have thrown it (which I can guarantee would have happened), it would not have felt good in his eyes, nose, or mouth.

Doing the activity with just my little preschooler let us add a scientific approach to our soap experiment and allowed her to free play, ask questions, and learn. I was so impressed with the great questions she was coming up with. One of her questions led us to making soap shapes.

Steve Spangler Science provides a great explanation about the science behind the soap phenomenon and is where I found the directions. Basically, the soap expands for the same reason popcorn kernels pop. Ivory soap is whipped so it is full of tiny air pockets that expand when heated up. I planned on making popcorn to go along with this activity, but we had so much playing with the soap we ran out of time.

Ivory bar soap
Paper plate
Cookie cutters (optional)

1.  To add some science to the activity, do the following:

  • Fill a bowl with water and ask your kiddo if they think the soap will sink to the bottom or float on the top. Ms. Tiger (age 3.5) guessed it was going to sink to the bottom. When I dropped the soap into the water and it floated to the top she was amazed and immediately opened another bar of soap and dropped it in the water.
  • Let child push soap down to the bottom of the bowl and watch it float to the top. Talk about what would make the soap float-weight and air
  • Ask kiddo what they think will happen when the soap is heated in the microwave. Ms. Tiger thought it was going to melt. I was seriously impressed with her guess.

2.  Now To The Activity: Put the soap on a paper plate in the center of the microwave and turn it on for two minutes. Our microwave is above the stove so I let her stand on a stool so she could watch the action. The both of us watched in amazement as the soap just kept growing and consumed the inside of our microwave. After one minute I pulled half of it out and placed a large portion of the soap that had moved from the center of the microwave back in place and continued microwaving for the remaining minute.

We pulled the soap out and put it in a bowl to play with. It was so fluffy that the first thing we did was crush it in our hands. It is amazingly light and airy.

This is one happy little girl

We added glitter to it and continued to sift it through our fingers. It kept Ms. Tiger quietly entertained through all of Mr. Tickle’s nap time.

So pretty, it reminded us of Frozen

3. Make Soap Shapes: Add water to the soap flakes until the soap flakes are moist throughout. I let Ms. Tiger use a water bottle to squirt water into the flakes and stir. She loved it! It reminded me of thick, lumpy, pancake batter. Pour the soap mixture inside a cookie cutter and let set.

I was surprised at how fast it set up. I removed the cookie cutter and set it outside for further drying (in hindsight I should have left it inside). I would like to say that we loved using our homemade soap shapes but our dog ate it as well as another project we had in process…at least the other project was meant to be edible. I am happy to report that he is still okay despite eating soap.

Now don’t delay and go blowup your own soap. You are seriously missing out if you haven’t done this yet! 

(Update) Here is another fun science experiment we recently did: 


For more easy science ideas, follow our science board on Pinterest.


Thanks for joining us!
Love, Katie & the Kiddos


  1. This would be so much fun to make with the kids!! I might enjoy it more than they will. 😉

  2. I'm doing this with my kids ASAP .. it looks like so much fun ! I love it !!!! Tnx for the share.. As I said – Amazing blog.. keep up the good work !

    1. Hi Biljana, thanks so much for the nice comments and for visiting!!! Have fun, I am sure you and your kids are going to love this activity!!! 🙂

  3. Wow Katie, this looks sooo fun! I will read through instructions but was wondering if there are ANY Soap Bar alternatives you have tried or is it a IVORY MUST? Thank you for sharing

    1. Hi Jeanine, from what I have read Ivory soap is a must because it is whipped. The air pockets in the soap is what makes it expand. Enjoy! This activity is so fun, my daughter asks to do it again every day,

    1. Hi Jennifer, thanks so much for stopping by and for the wonderful feature! I appreciate it! 🙂

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