How to Make Ice Cream Quicker using Heat Transfer!

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Our family recently bought an ice cream maker. While enjoying our first batch of ice cream, we talked about what flavor we wanted to make next. My middle son said, very excitedly, “I want to make rainbow ice cream!” I started to think about ways to meet his request, and my thought was to make 6 batches of vanilla ice cream of all the colors of the rainbow. But our new ice cream maker would make huge batches. Then I remembered a simple way how to make ice cream at home. Unfortunately, it took a long time. Remembering something from my heat transfer class in college, I thought if we changed the amount of one ingredient, we could speed up the process. I gathered all the boys together, and we learned how to make ice cream quicker together!

A fun science ice cream experiment to do with all your kids! Find the fastest way to make ice cream at home.

How to Make Ice Cream as Quickly as Possible!

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We live in Texas, its summer, and right now its HOT! Add that to the lack of patience of my three boys, and finding a way to make ice cream quickly would be nice. More than nice. A dream for this stressed out mom!

My son’s request for rainbow ice cream gave me an idea for an experiment. When my oldest was in kindergarten, he had made ice cream in a bag. But I remembered it took awhile. Of course, we could jump in the car, and drive to buy some ice cream, but if you have 3 young boys, you know this is NOT an option. So I thought of an experiment to figure out how to speed up making ice cream in a bag.

Following the instructions from this recipe, we set off to make 6 batches of ice cream!

Step 1: First I poured the cream, sugar, and vanilla from the recipe into a small ziplock bag. Then I added a few drops of red food coloring into the bag.

Step 2: I repeated step 1 with two more small ziplock bags. I added green food coloring to one, and blue food coloring to the other. I labeled each bag with the first letter of each of my sons’ names, so they wouldn’t fight over who got to make which ice cream. Mommy win!

A fun science ice cream experiment to do with all your kids! Find the fastest way to make ice cream at home.

Step 3: Next I gave each one of my sons a large ziplock bag, and had each of them pour 8 cups of ice into their bag.

Step 4: The post with the recipe had a great explanation of the science behind making ice cream. But I was curious if we could make our ice cream faster if we added more salt to the ice bag. To test this theory, my youngest son put 3/4 cup of rock salt in his bag of ice, my middle son added 1/2 cup salt in his bag, and my oldest added just 1/4 cup of salt.

A fun science ice cream experiment to do with all your kids! Find the fastest way to make ice cream at home.

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Step 5: We placed the red bag in my youngest son’s bag of ice, green in my middle son’s bag, and blue in my oldest son’s bag of ice.

A fun science ice cream experiment to do with all your kids! Find the fastest way to make ice cream at home.

Step 6: Then they rolled their bags of ice around, while I kept track of time to see how long it took each bag of cream and sugar to become ice cream.

A fun science ice cream experiment to do with all your kids! Find the fastest way to make ice cream at home.

Notice we put some socks on my 2 year old’s hands. The bags get really cold!

Step 7: We repeated steps 1 through 6 for the colors orange, yellow, and purple.

When running an experiment, always make sure that your results are repeatable. Repeatable means when you run your experiment more than once, and you get the same results both times.


Both times we ran our experiment, the milk in the bag of ice with 3/4 cup of salt was the first to turn into ice cream. The bag that took the longest to turn into ice cream was the bag with only 1/4 cup of salt.

So, the more salt you have in the ice bag, the quicker your milk will become ice cream!

The Science Behind our Experiment

Adding salt to the ice lowers the melting temperature of the ice. While the ice is melting, it is undergoing  a endothermic reaction. An endothermic reaction means that the ice is taking energy, in the form of heat, from its surrounding area. So while the ice is melting, heat energy is transferring from the small bag to the large bag. The less energy in a substance, the less their molecules move. Eventually, enough energy transfers from the milk/sugar mixture that the molecules essentially stop moving, resulting in a solid. In this case our solid is ice cream!

Adding more salt to the ice speeds up melting, thus increasing the endothermic reactions. Which is why the cream in the ice bag with the most rock salt became ice cream the fastest!

Rainbow Ice Cream

From the experiment, we had all the colors of the rainbow. Now it was now time to make the rainbow ice cream my son wanted!

Step 1: I found a mason jar big enough for all the ice cream.

Step 2: Next I slowly poured the red ice cream into the mason jar.

A fun science ice cream experiment to do with all your kids! Find the fastest way to make ice cream at home.

Step 3: Then I put the jar into the freezer, along with the remaining 5 colors.

Step 4: I repeated steps 2 and 3 for each color. After pouring the purple ice cream into the jar, I returned the now full mason jar to the freezer one last time.

**Tip: Remove the ice cream still in the bag from the freezer to defrost a little before adding it to the mason jar. Defrosting the ice cream will make it easier to pour and level inside the jar. Also make sure the ice cream in the mason jar is completely frozen before adding another color on top.**

Step 5: Once the purple ice cream was completely solid, I removed the mason jar from the freezer, and voila! Rainbow ice cream!

My little boy was so excited to eat his rainbow ice cream!

I loved I could involve all 3 of my boys in learning how to make ice cream fast. I really want to find more experiments that involve all three of them. Do you have any ideas for experiments you can do with multiple kids? I’d love to hear your ideas!

Did you enjoy our summer time experiment? Then you’ll love my other science experiments!

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