From what I know you heat up the flanel soaked in castor oil. Then you put it on tinfoil or plastic (but plastic has toxins in it so I avoid it) this foil or plastic will prevent your heating pad from being soaked in oil. You put the flanel part of the pack towards your body over the ill area you want to treat and apply a heating pad. You will need some old rag or a towel you decide to sacrifice because the oil leaves permanent stains on textile. Sit or lye on the rag, you may drip oil and keep it on you for an hour. It works much like acupuncture, that is, it increases energy flow. It also increases blood flow and I've read somewhere that you should not use it if you have your period and are a heavy bleeder. I didn't beleave this myself and tried it for pain reduction during a period. I was bleeding SO heavily I'll never do it again. But I use castor oil packs regularly to try to reduce endometrioma cysts.
Lisa