That reminds me of what Rick was saying a chunk of years back, when other people were saying that alcohol was a better solvent for extraction, when making what has been come to be known as "Rick Simpson Oil."
He chose PURE naptha, as it seemed to provide a fuller extraction of the active cannabinoids than other solvents. Trouble is, people didn't like to listen when he said PURE naptha, or that ALL of the solvent needs to be removed.
Note: The man who coined the term "Rick Simpson Oil" was the one and only Jack Herer, for those who didn't know. Rick still calls if "hemp oil" or "cannabis oil" or "hash oil." All those terms are pretty much interchangeable, as they all refer to the "whole plant extract of the cannabis plant."
I'm aware of the misunderstanding people have, and I still have personal issues with naptha itself. I simply do not touch my cannabis with petroleum products. Period. No worries, I simply make sure I give people full disclosure when I share my cannabis. It's the decent thing to do. :)
I understand where you're coming from. Rick himself--despite what you may have heard--also understands, as he can see that not all people have an engineering background, and are capable of building distillation systems capable of removing ALL of the solvent.
For that very reason, he has said that ethanol can be used, as it's easier to get the last bits of solvent out of the end product.
Personally, I don't trust the idea of isopropyl since it's far more toxic than ethanol (a.k.a.: booze), and can cause blindness, among many other types of physical damage, if it is not COMPLETELY excised from the final product.
A lot of people "assume" that pharmaceutical chemicals (which is what they all REALLY ARE) are NOT made with a thousand different solvents...and many of them are far more toxic than PURE naptha. Trouble is, few people are interested in looking into things once they've gotten "what they believe is an unchanging scientific fact."
Take "anthropogenic global warming"...err..."global warming"....err..."climate change"...err..."carbon pollution"...err...you know..."the science is settled." d=^/
PS: I also don't much care for the idea of butane extractions...especially since most butane is sold with rust inhibitors, as is naptha, so you end up with the exact same problems of contamination, although you never seem to hear THAT mentioned.
Isopropyl alcohol does accumulative damage. Sam the Skunkman states he's tested more extractions than probably anyone. Not once, no matter how many times it was "washed or purged," has he ever had an iso extraction test negative for iso. Bleah.
Yeah, ethanol is great because I don't need to worry about the tiny residual alcohol in it. Not a bit.
Professional butane extraction companies re-distill large quantities of butane, for the sole purpose of removing mercaptans and other mystery oils. Significantly cleaner than most DIY extractors, I still prefer ethanol. lol To each their own. :D
I love NOT being the only person who's ever done some actual research into THE ACTUAL FACTS. d=O)
A good starting point for those who haven't yet started looking: