How do hand warmers work?

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How do hand warmers work?

Far from being a mystical item, hand warmers use some basic chemistry to keep your digits warm. Sit back as we break down the science for ya!

Brian Connelly
Brian Connelly
Last Updated: February 4, 2020

Want to Know How Hand Warmers Work?


    • How disposable Hand Warmers Work
    • How Reusable Chemical Warmers Work
    • Which Outdoors Situations Are They Useful In

Helping keep your hands warm in the coldest conditions, hand warmers have been able to keep people warm for many years. However, there are a lot of unknowns to go over about how hand warmers work and when they should be used.

We’ll take a look at some of the things that make hand warmers work, some of the best times to use them, and answer some of the most frequently asked questions about hand warmers.

How Hand or Toe Warmers Work

Hand warmers may seem like a mysterious tool unless you have a degree in chemistry. Like most chemical reactions, a mixture of products combines to create a reaction and produce heat.

Air-Activated hand Warmers

These are the most common types of hand warmers and are probably the variants you have used in the past. As the name suggests, air-activated hand warmers work when the hand warmer is removed from its package and exposed to air.

The air-activated hand warmer generally contains iron powder, water, salt, carbon, and cellulose, which all act together with the air to create a chemical reaction. The air and the iron powder combine to form iron oxide, with salt being used as a catalyst to speed up and intensify the reaction.

This rather intense chemical process produces lots of heat when oxygen from the air is introduced into the mix. The finished supersaturated solution is a one and done event and lasts up to around 10 hours before the contents no longer react, and no further heat is given off.

Chemical solution Reusable Hand Warmer

Similar to the air-activated hand warmer, these variants rely on the combination of certain compounds to generate heat via an exothermic reaction.

In most chemical solution hand warmers, a metal strip is inside of a package and must be bent to start the process. When the metal strip is bent inside of the packaging, it allows for the metal to mix with the sodium acetate solution that surrounds the metal.

The bent metal allows for a reaction to occur where crystals of sodium acetate form on the surface area of the metal and generate heat. This process only lasts for up to 2 hours, but the process can be reversed by boiling the hand warmer in a water reservoir to melt the formed crystals and bring the mixture back to its original state.

Keeping Your Hands Warm When in the Outdoors

In colder weather, your body is only focused on keeping your core warm and removes the blood from your hands and feet to do this. When the blood leaves your hands, they lose most of their internal warmth and are no longer able to function as they would be able to in normal conditions.

Hiking & Backpacking

Hiking can connect you with the outdoors and bring you as close to nature as you can get. Exploring the wilderness and camping in complete silence is an experience that everyone should try at least once. The conditions that you hike in can change in an instant, so you need to be ready for anything.

If you enjoy backpacking, then you are undoubtedly aware of the importance of your hands. From setting up your tent to making a fire, the feeling of numb hands that are sensitive to every movement can make even easy tasks an absolute nightmare.

Keeping your hands warm with your hiking gloves can only do so much as you are still relying on only your body heat for warmth. Taking disposable hand warmers with you will help remove the chill from your cold hands and let you do the task at hand.

In fact, I sometimes slip a hand warmer inside my glove on particularly frosty mornings – it helps me brush off the chill of the morning.


Bowhunting is essentially the connection between man and tool to accomplish a task. However, in cold weather, using a bow becomes increasingly difficult for even the most skilled hunter. Drawing a bow and releasing the strings to shoot the arrow is hard in normal weather and feels like torture when your hands are freezing.

In a situation where you would need your hands, and it is colder than usual, hand warmers can save your trip. For example, if you are hunting elk with your compound bow on a winter’s morning, you will need every ounce of strength and control from your hands when you take your shot.

Similarly, if you hunt with a crossbow, being able to pull the trigger is the difference between a trophy kill and a sad drive home. Handwarmers can keep your hands warm when you need them most and helps keep you ready for any action at a moment’s notice.

Recommended Reading: If you are new to bowhunting, we recommend you check out this post at Arrows2Bows about bowhunting for beginners.

Sporting events

Hand warmers are great for some of the most stimulating experiences one can take part in, but they are also useful when merely enjoying life on the sidelines. From football to ice hockey, watching sports is always a great event and makes you feel like you are right there, playing alongside your favorite team.

One thing that ruins the fun for any sports fan is having to sit through a long game and losing feeling in your hands. Keeping a pair in your favorite sports team hoody will keep your hands warm and your spirits high for the whole game.

Frequently Asked Questions

Are hand toe warmers dangerous?

Hand warmers rely on a powerful chemical reaction to work but are not designed to be dangerous. Unless you open up the chemical packet and expose it to your skin, it will not present any serious dangers to your body if you use it as designed.

Does shaking hand warmers make them warmer?

It may seem silly to see people shaking hand warmers in an attempt to make them warmer. It may seem strange, but shaking the hand warmers does speed up the reaction and generates more heat.

By shaking the packet, you are increasing the speed of the reaction that takes place, making the disposable hand warmers heat up faster.

Further Reading: For more ideas on how to keep your digits toasty, check out our ten tips on how to keep your hands warm in cold weather.

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