• HotSnapZ reusable hand warmers and heating pads contain water, a small metal disc and sodium acetate, a safe food grade salt ingredient.

• When first boiled the mixture inside the pouch is heated to completely dissolve the sodium acetate in the water. This makes the contents clear and liquid.

• After cooling, the sodium acetate remains dissolved producing a solution that is supersaturated.

• This means that the heat energy that was required to dissolve the sodium acetate into the water still remains in the system even though the temperature has dropped. Almost like a Heat Battery!

• The clicking of a disk within the pad triggers the precipitation of the sodium acetate crystals. When the crystals precipitate, it releases the energy that was required to initially dissolve it and stored in the pouch.

• The release of energy raises the temperature to a maximum temperature of 130F (54C). The process is theoretically repeatable indefinitely. HotSnapZ are a sodium acetate hand warmer.