To Trigger The Heat Pack:
The heat pack contains a food grade salt/vinegar solution which is activated by flexing the small metal disc inside the pack. As the crystals form, the pack gives off heat. The heat pack works best if it is continually flexed while the crystals are forming and for a few minutes afterward. Once the pack is warmed, keep it protected from cold inside coats or blankets. This will provide the longest warming advantage.
To Recharge The Heat Pack:
As the pack cools, it transforms into a solid salt pack. Recharge the crystallized pack by placing it in boiling water until all the crystals are melted. The heat pack will liquefy at approximately 136 Degrees F/ 58 C. The solution will remain liquefied as the pack cools. Once liquefied, it is ready to use again. The recharging process can be repeated over and over, providing nothing punctures the skin of the pack. Store the heat pack in liquid state away from sharp objects, and in a warm area (It may crystallize if stored below 15 degrees F)