... through putting the pad into the freezer, after 45~60 minutes, when you are ready to use then take them ... in boiling water with cloth below for about 5 minutes until all the crystals disappear, then recharge it. ... the metal disc; take it out after 20-30 minutes, as cold pad. Used frequencyRecommended use twice a ... day,each time of 20-30 minutes for heat/cold. Validity 3 Years.Storage and ...