Iso whats wrong

Hey folks first time poster here ive been trying my hand at iso oil ... Im using 99% iso but when i finished my last batch it was hard (like it needs to be geated to get a pin in it) yet when i put a flame to it it cracles burns and produses a black flame im not sure what im doing wrong ... I feel ive evaporated it to much making it hard but it slike theres still alcohol causeing it to crackle any advice? ...method I make the wash in the freezer put the mixture in a pyrex dish put the dish in an electric frying pan full of water

Thanks for any help ... And all the info you guys have given me to get to this point

I havent made it yet (have all the fixings just need some time and decent weather) so take my reply with a gran of salt.

Hash burns black..so oil may as well.??.. (been decades since i last saw oil)

It does go hard if its evaporated to long, thats normal. I think they call it Shatter??

Concentrates typically burn with a yellow flame and put out copious black soot. Crackling is typically retained water.

A black flame? Seems unlikely. Crackling is usually water, as mentioned. Guess it could also be sugars or something, if it soaked too long. Hard extract is a good thing, thin means lots of leaf oil. You gotta try to avoid breaking up the material to avoid leaf oil, which is only good for edibles, if that.