I previously used CO packs in sauna.In recent times I have simply massaged the oil into area desired. Apart from usual areas I apply to reach a deep muscle the piriformis-am an athlete and the syndrome produces sciatic pain which was difficult to treat.
One can see that the oil has been absorbed completely.There is no cleaning up to be done.Flannel etc only added inconvenience -useful if one is unable or unwilling to massage the oil in or when one does not have a sauna of course.