What makes you think its safe?
Do you have anything from NCBI stating thats its safe to ingest?
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oh you meant straight ingestion. I meant as a solvent, later evapād off. Nevermind then 
Yeah, you ingest the product, right??
And theres no way to completely remove a solvent. But even that is not the point.
ISO leaves behind metabolite residues that are both toxic to the liver and kidneys.
You should really do the research before playing chemist - this is how people get hurt with cannabis and really gives the whole thing a bad name.
So, stick to food grade ethanol and quite harming people to save a few bucks in overhead. Its cannabis, youāre gonna make money anyway.
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Isopropanol? Ideally not 
Maybe you wont get 0ppb of solvent out here in the real world but you can easily get low enough that itās not relevant. A study here found iso gas is detectable by nose around 11-39ppm. I can attest that when an evap dish is low enough, when itās a bead of liquid instead of wetting the whole pan, I canāt smell iso. The CDC says here:
"Ten volunteers exposed for 3 to 5 minutes to 200, 400, or 800 ppm reported mild to moderate irritation of the eyes, nose, and throat at the two higher concentrations [Nelson et al. 1943]. The probable lethal oral dose has been reported to be 190 grams [Gosselin et al. 1984]. [Note: An oral dose of 190 grams is equivalent to a worker being exposed to about 50,700 ppm for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]"
Additionally, a publication on isopropanol toxicity from the ncbi (here) says āTreatment of isopropanol ingestions typically consists of supportive therapy. Ingestions are rarely lethal [1][2][3]ā Combined with the facts iso evaporates faster than water and actually pulls water out of the air into the evap dish, lengthening the evap process, residual iso content is not a concern imo.
Could you tell me more about these āmetabolite residuesā? I found a sales data sheet from DOW on their USP grade iso (here) that states a max allowance of 1.4mg/100ml of ānonvolatile residuesā (afaia USP grade is what they sell in drug stores). Iām estimating a typical home batch of qwiso ran in a mason jar might have 10-20mg of this residue (supposing you use 1 liter of iso and theyāre really toeing the line of the spec) spread across several thousand mgās of hash. I doubt theyāre of much concern either but if you know more Iād like to hear it.
I can understand your concern, but I would appreciate if you cited some sources before getting hostile and jumping at me about it Iām perfectly happy to be wrong, especially when safety is a concern, Iām just not convinced I am. Oh and for the record Iām no dealer, I donāt make money from my passion sad to say 
Then again passion and business donāt always mix well
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Hi ChongoBongo, the following site has some information and links to reference studies. One really have to read between the lines on what theyāve stated as related to your personal situation. I havenāt looked closely myself:
It is difficult to remove all of the solvent even under vacuum distillation as it can develop azeotropes with other substances that have different boiling points than expected. There may be a cumulative toxicity effect when consuming isopropyl alcohol, even if itās below industry safety limits. This is where youād want to research. Using ethyl alcohol as a solvent is probably safer but it also much more expensive.
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Iāve moved some of the relevant content to this thread.
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Hey Northern_Loki, I appreciate the link and the info on azeotropes 
Going over the link it seems a little fearmonger-y. It looks like mostly studies on long term exposure to people in industry working closely to ISO on a daily basis, and occasionally shorter term, large exposures (eg a chemical spill in an industry setting, being sponge bathed with it in a hospital, etc). Quite a few of them involved exposure to multiple chemicals, not just iso. Iām guessing itās not all necessarily USP grade ISO theyāre being exposed to either; industrial grade has lower standards. I donāt think this is comparable to occasionally inhaling objectively miniscule amounts of medical grade ISO that may be present when smoking qwiso dabs.
I canāt smell iso in my qwiso even when itās still evaporating (at the later stages of evap) which the study I quoted above suggested could be detectable down to levels as low as 39-11ppm. I donāt doubt those industrial workers are getting strong whiffs of it here and there all thru their shift, for years and years.
It has some other studies which say things like participants who took one half to about one full shot glassās worth of 50% iso got headaches for a few hours. How many dabs do you think it would take to approach that level of exposure? Imagine smoking half a shot glassās worth of dabs, then imagine how much dabs it would to take to get half a shot glass full of iso 
They quoted a study that I quoted above, (Nelson et al., 1943), which showed participants who were exposed to 200ppm of iso gas for 3-5min did not report any mild or moderate irritation symptoms. I can understand paranoia, we all smoke weed here 
but I think this is much ado about nothing. You may as well worry about carcinogens in combusted plant material or heavy metals and offgassing in vapes, in which case you likely wouldnāt be here to begin with 
As to azeotropes, Iām not savvy in chemistry but if Iām reading it right it suggests that it may make the iso harder to separate from water or other chemicals via distillation. Iām not worried about the water, Iām getting rid of that too so if they evaporate off together Iām not concerned. But if the iso wants to stick around my terps et al? Interesting. But at this point I can only consider it speculative - regardless of this phenomenon it hasnāt been established that a noteworthy amount of ISO is left over in the hash to worry about. If a significant portion of the iso, enough to harm me, is being held so strongly in solution by azeotropic principals such that I canāt smell it boiling off a liquid solution (which Iām doubting), then I suppose there would be other tell tale signs of iso being present, such as dizziness, headaches and throat irritation after consumption. I donāt smoke a lot of qwiso but Iāve never had these symptoms following a dab of it. Iām just not convinced itās worth worrying about 
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