BHO all the way..my toes curl in the wrong way when I think of the propane taste in the oil, wax etc
Propane is a simple C-3H8 Alkane, and Butane is a C-4H10 simple Alkane. Both fully saturated, with a dielectric constant around 1.3, so not attractive to metal ions, as compared to things like water with a dielectric constant of around 80.
I agree that 100% Butane extracted oil is more flavorful than 100% Propane extracted oil, but isn't the taste of the Propane, just what they extract by themselves.
Blends can be quite flavorful and allow you to chill the LPG mixture below -30C so as to avoid extracting the longer chain molecules above the C-22 Cannabinoids, like C-40 b-Carotene, et al. Straight butane doesn't flow well below -30C, and the propane thins it some.
Propane is actually easier to purge and has less taste than butane. Propane is considered odorless, and Butane almost so, which is why they typically add Mercaptans for leak detection for most applications. It is important that you not purchase either fuel intended for that purpose, as it will leave Mercaptans behind in your concentrate, adding it's delightful garlicy flavor.
We buy 99.5% Instrument grade and redistill it to 99.998%,to get out the really nasty tasting mystery oils, which are typically longer chain hydrocarbons as high as C-18.
Instrument grade has very little mystery oil in it, but when we re-distill lighter butane, we remove a significant amount with some brands and some with all.
