Rice Heating Bag with Essential Oils Put 10 drops of essential oil in 2 cups of rice and mix it together. I used Peppermint. Pour into a knee sock. Tie off tightly with a shoelace and trim ends of shoelace and sock if needed. Heat in microwave for 1 1/2 -2 minutes and then use as heating pad. Can open and add more oils when scent wears off.