Science Projects > Chemistry Projects > How To Make DIY Hand Warmers 

How To Make DIY Hand Warmers

Perhaps you’ve toted a pack of commercial hand warmers along to a football game or crammed them into the toe of your ski boots.

But did you ever think about how to make DIY hand warmers?

While there are various types of commercial hand warmers, this version uses rusty iron filings. With salt, iron, and water, you can create a instant pocket-portable heat source!

These homemade instant hand warmers don’t need a microwave or sewing machine.

Instead, you’ll learn how to make DIY hand warmers the easy way—with science.

What You Need:

What You Do:

how to make DIY hand warmers - mix chemicals

1. Put 30 grams (approximately 1 1/2 tablespoons) iron filings in 3×5 zip-top bag.

2. Add 1 1/2 tablespoons salt.

3. Add 1 1/2 tablespoons sodium polyacrylate.

4. Finish with 1 1/2 tablespoons of warm – NOT hot – water.

5. Carefully remove air and zip bag closed.

6. Place 3×5 bag inside 4×6 bag. Carefully remove air and zip bag closed.

7. Shake, squeeze, and knead the mixture for 30 seconds or so until a slush forms inside the smaller bag and the water is completely mixed in. Be cautious to set the bag down if it gets too hot.

What Happened:

To truly understand how to make DIY hand warmers, you need a basic grasp on chemical reactions first. So what is a chemical reaction? It’s when a substance (like iron or salt) is altered in some way, also know as a chemical change.

how to make DIY hand warmers

This occurs in various ways: Two or more chemicals can combine into one, two chemical compounds turn into two different chemical compounds, or one chemical compound separates into two or more chemicals.

For your homemade hand warmers, you combine the iron filings with salt, air, and water, which released iron oxide, or rust.

This chemical is considered an exothermic reaction. Exo means out and thermal means heat, so an exothermic reaction is literally one in which heat (or light) is released.

In this case, while the oxidation is occurring, heat is released. The sodium polyacrylate, or water gel powder, helps lock in moisture so the chemical reaction can take place. But once the air-activated process is complete, no more heat will be emitted—this can take from one to several hours!

Safety note: To avoid tetanus exposure, throw away hand warmers when you’re finished experimenting.

Further exploration:

How does the reaction change if you add more iron filings? How does it change if you add less?

What about the other ingredients? How does adjusting the ratio of salt or water gel powder affect the reaction? Repeat the experiment using varying amounts of materials and record your results.

Use a lab thermometer to record the temperature of each experiment.

Use a stopwatch to time how long the bag stays heated.

To Learn more about natural nuclear and human-made nuclear reactors by making hand warmers, model nuclear energy release and radioactive decay and half-lives with this symbol experiment, and analyze the pros and cons of nuclear power, check out our Science Unlocked kit Naturally Nuclear.

Chemistry

Welcome! Read other Chemistry articles or explore the rest of the Resource Center, which consists of hundreds of free science articles!

Shop for Chemistry Supplies!

Home Science tools offers a wide variety of Chemistry products and kits. Find affordable beakers, test tubes, chemicals, kits, and everything else you need for lab experiments.

Related Articles

Weekly Lesson Plan Sheet for Homeschool Science

Weekly Lesson Plan Sheet for Homeschool Science

Want to make planning your children’s homeschool science school calendar simple? Who doesn’t?
We created this handy planning worksheet you can use for any student, K-12 to make lesson planning easier and faster.

K-12 Science Curriculum Guide

K-12 Science Curriculum Guide

Selecting a science curriculum that’s a good fit for you and your students is the first step toward a great science learning experience. Because every teacher-student situation is different, there is no one science curriculum that is best for every homeschool family....

10 Science Experiments You Want To Do This Year

10 Science Experiments You Want To Do This Year

Science experiments are one of the most fun things you will get to do in your homeschool or classroom! You’re not only learning and applying knowledge — you’re also having fun! I've put together some really fun and easy science experiments for you and your family to...

should I learn computer coding