K, let's clear up some stuff here so's we don't get future newbs all confused and stuff..
First off, y'all need to consider using 99(.8)% iso, str8 up. If you can't get 99%, do something else..
Hammy bro, you were on to it mate
If you are worried about what iso will leave in the final product, then you are not purging correctly. Iso will evap clean, it's what alcohol does. If there are doubters here, try the same glass test that we use for butane.. Then try it with tap water..
Firstly, avoid grinding your material into powder (fine grind). A simple chop would do fine, if needed at all. I do like to break up popcorn bud though, otherwise a bud just becomes a sponge that will have to be dealt with some how.. Also, let it dry completely. No wet material!
Next, freeze it. Freeze it all. The iso, the bud, the jars they are in, everything.
Once that's done, study the name of this technique. Qwiso means "quick wash" iso.. If you are getting tacky green or black oil, you have just missed the tug. Like BHO, iso should come off fairly clear. Unlike BHO, iso will have a 'redder' tint to it.
Ok, here's the rub.. "Quick wash" your material.. This means keep it under 15 seconds. Anything more can no longer be called 'quick wash'.. And do it all as cold as you can get it. This will help tie up unwanted plant lipids from draining into the final product.
Next thing to remember is to strain the material through a screen and take out the bigger stuff up front, then run it through your coffee filters..
Also, the best purge is a warm purge. Using a crockpot is a stellar idea, and I do it my self but with a clear pyrex-type container inserted in or over the ceramic insert. Once the iso has evaped, I also use my oven, generally set below 300f. Here is a guide that will help on time and temps. Note: THC decarbing won't change your smoke, but if you plan to injest then decarbing is a must.
Ok, here are some things to consider.. When dealing with iso the one thing you should be shooting for is a window of quality that leaves your oil stable at room temp. If you wash too long your oil will become dark, soft and extremely tacky. The best quality will be very stable at room temp and will shatter if handled even midly rough. There is a better quality that can be reached, but not with one iso wash. Adding a second wash, done with ethanol in a technique being called 'winterization' (I know...), you can free your iso results from all plant fats and excess lipids (Google: Absolute Amber). However, seems this will also bring your oil back to a free running, viscous product and drops it's stable form.
Either way, here's the deal. When using iso as a solvent, and you end up smoking this..
Then you probably have a reasonable gripe.....