How Do Chemical Hand Warmers Work?

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Whether you are camping, hiking, skiing or snowmobiling, there is one piece of equipment that should always be carried with you. That equipment is the chemical hand warmer. Not only is it a great thing to have to keep your hands warm when out for recreational activities, it can also be a lifesaver to keep your hands or feet warm during and emergency where you may be stuck in the cold for an extended period of time.


Chemical warmers are made up of a combination of iron, activated carbon, cellulose, vermiculite, water and salt. These ingredients are wrapped in a container that keeps out any oxygen from interacting with the ingredients inside the warmer.

The Reaction

Chemical warmers work by a chemical reaction. When the warmer is unwrapped, oxygen is allowed to mingle with the ingredients inside the warmer. When the oxygen hits the iron in the warmer, it causes the iron to oxidize. The chemical reaction releases energy in the form of heat.

Salt and Polypropylene

The salt in the chemical warmer is an important ingredient because it works as a catalyst. A catalyst is a substance that speeds up a chemical reaction, or in this case the reaction between the oxygen and the iron. The polypropylene works by allowing the oxygen to circulate without evaporating all of the water.

Carbon and Vermiculite

The carbon acts as a dispersant agent. This allows the heat to spread throughout the chemical hand warmer equally. The vermiculite works by insulating the hand warmer. This keeps the heat from escaping too quickly and allows the chemical warmer to remain warm longer.

About the Author

Chris Sherwood is a professional journalist who after years in the health administration field and writing health and wellness articles turned towards organic sustainable gardening and food education. He now owns and operates an organic-method small farm focusing his research and writing on both organic gardening methods and hydroponics.

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