Hand warmer

Matoba received a patent for applying the principle of an oxidation reaction that produces heat by means of platinum catalysis.

[4] Air-activated hand warmers contain cellulose, iron powder, activated carbon, vermiculite (which holds water) and salt.

The reaction begins as soon as the package is removed from the pouch, thereby exposed to the air, typically in a glove or pocket of a jacket.

[8] This type of hand warmer can be recharged by immersing the hand-warmer in very hot water until the contents are uniform and then allowing it to cool.

The release of heat is triggered by flexing a small metal disk in the hand warmer, which generates nucleation centers that initiate crystallisation.

These hand warmers are for people who work or pursue leisure activities outdoors in very low temperatures, especially those that require manual dexterity that is not possible while wearing thick gloves or mittens.

[12] John W. Smith, President of Aladdin Laboratories, Inc. of Minneapolis was awarded a US patent for a product called the Jon-e (pronounced “Johnny”) catalytic hand warmer on December 25, 1951.

Typically made of metal to act as an even heat spreader, these cases often have comfortable felt on the outside and sometimes a fire-proof insulative lining on the inside.