How’s that for an oxymoron?
The same coating of iron oxide that destroys your car when the weather turns cold can also be used to heat your hands while you drive. Iron is the main ingredient that puts the ‘warm’ in warmer. Tiny pieces of iron , among other ingredients are dispersed in the heat pack in the initial process of mixing. The primary sealing used is a permeable membrane that allows for oxygen (air) to enter and make it “oxidize” the iron. However, a secondary sealing is used to prevent that process until the warmer is ready for use.
Oxidation is what causes most of our heat on Earth. For example, when a tree burns down, the tree’s carbon is oxidizing. Carbon can give off heat when oxidized as well. So why isn’t all of the iron around us constantly heating up since it is exposed to air on a regular basis? This is where other ingredients come into play. The iron in the heat packs is surrounded by salt which is what allows the “oxidation process” to go much faster. We use salt in warmers for the same reason we use salt on streets to “de-ice” them. The salt eats iron. Finally, charcoal is used as a carbon to spread the heat around and vermiculite keeps the heat from escaping too fast. The warmer runs out of heat when all of the iron has oxidized and then heat has dissipated.
The best part of the whole process?
The ingredients of a Heat Factory Hand Warmer are biodegradable.