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The solution in Wonder Warmers® typically freezes at approx. 130° F (54° C). However, the pouch which holds this solution does not provide the solution’s molecules with enough surface area to form a crystal lattice, or in other words “to freeze”. This solution can therefore remain as a liquid even though its temperature is well below its freezing point. By flexing the metal disk in your Wonder Warmer® you cause a few molecules of the solution to crystallize. These crystals in turn provide the surface area required for the rest of the molecules of the solution to crystallize. This “freezing” process (i.e., transition from liquid to solid) is an exothermic chemical reaction, which releases energy and generates heat (approx. 130° F, 54° C).

Wonder Warmers® are made of a PVC pouch, which contains a small steel disk and a solution of water and a type of salt, which is non-toxic.

Your Wonder Warmers® will generate heat from 30 minutes to 3 hours depending on their size and how well you insulate them.

Insulating your Wonder Warmers® by keeping them in your pocket, sleeping bag, or any other type of heat retaining wrap will prolong their heating time. You should also knead your Wonder Warmers® after activation to increase their temperature and keep them soft and malleable.

Wonder Warmers® can typically be used well over one hundred times. You should be able to use your Wonder Warmer® until its PVC pouch is punctured.

If your Wonder Warmer® is punctured while it is in the liquid state it will activate for the last time. Damaged pads should be promptly disposed of.

Crystals may sometimes form in your Wonder Warmers® due to evaporation if they are stored in their crystal state (i.e. as opposed to being stored in the liquid state as recommended). These crystals will not materially impact the effectiveness of your Wonder Warmers® and can be dissolved by boiling your Wonder Warmers® for longer periods and allowing them to cool in water.

When recharging your Wonder Warmer® you must boil it until ALL the crystals in the pad are fully dissolved. If you still see some crystals in the pad after you boil it, apply some pressure to the stubborn crystals and/or boil the pad for a few more minutes to dissolve them. If ALL the crystals are not dissolved, the pad will self-activate as it cools.

Your Wonder Warmer® can be used as a cold pack. You should place your Wonder Warmer® in the refrigerator for an hour or more to chill it before use. However, you should not place your Wonder Warmer® in a freezer as it will self activate.

We’re still trying to figure this out.