You can use it as is, for that matter. A dual solvent solution to start with, so to speak. Or just use 91% IPA from the drug store. Or 70% for that matter. I personally prefer using very dry alcohols for at least one of the rextals because its such an easy way to take so many salts you don't want out of the pile-- so many of them are water soluble that if you use a wet alcohol to start with you keep them around... when you could just filter them out. I like to do one rextal with ISO and one with MeOH, filtering out any solids each time.