Just going by what bill said: he was going to use Rick Simpson's recipe & rick never used ethanolNo personal experience making RSO but I do remember reading @medmanmike's post a few years back about how difficult (if not impossible) it was to completely purge iso from the oil, so I think ethanol is the safest way to go.
You can read MedManMike's post here about iso purging and what is considered "safe" for what remains. The conversation continues further down the page after that linked post.
It was either Naphtha or ISO