Last Updated on March 31, 2021Use a natural fiber case, like the cotton sock, and fill it with uncooked rice, dried beans, or wheat. Tie it as securely as possible and microwave it for three minutes—the bigger, the more minutes it needs. To enjoy a little soothing aromatic for extra relaxation, then use dried lavender or rosemary. However, keep an eye on the heat pack when it’s inside the microwave because overheating can create a fire risk. When it’s done, use a kitchen mitt to remove it from the microwave, then use it carefully.