Hand warmers – how do they work?: Science Course with Ryan Morse

Beyond The Forecast

(WFRV) – Normal high temperature to start November is 50 degrees in Green Bay. This means it is just about time for hand warmers to become a hot commodity.

Hand warmers have a variety of uses, from cold weather football games to hunting in the woods.

What makes a hand warmer – warm?

To find out you will need a disposable hand warmer or body warmer (I used HotHands), magnet, paper, sandwich bag, and scissors.

Tightly cover the magnet with the sandwich bag.

Then, cut open the hand warmer and dump it onto the sheet of paper.

Now – you have to act quickly – take the magnet and wave it over the contents on the paper. The plastic does not allow the iron to directly stick to the magnet.

If you don’t act quickly, a reaction will begin and the mixture will start to heat up.

The iron in the mixture, will separate from the other materials onto the magnet.

When you shake the hand warmer to make it warm, this speeds up the reaction of the mixture inside the hand warmer.

Oxygen in the air reacts with the iron in the hand warmer to form iron oxide, or rust, and heat. Shaking the hand warmer speeds up the reaction time by circulating more air in the packet.

This chemical reaction is the main reason hand warmers get warm.

There are other materials in the hand warmer mixture. Charcoal is thermally conducive which means it spreads the heat evenly across the packet. Salt and water in the mixture also acts to enable the reactions between the oxygen and the air.

The length of time a hand warmer will remain warm depends on the amount of iron used in the packet.

When freezing weather strikes, stay with Storm Team 5 on-air, online and on our app:


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