one of us is on the wrong track, you now say Butane which i heartly agree with, in your previous post you said Propane. stay away from propane because of the additives not the propane itself. maybe the oil has us both confused lol. BTW i think a well done batch should yield closer to 37% than 27%. the duration of the pain releif in the case of what i have made often exceeds 3 hours.