bho will be pure thc.. and unfortunately itll always have even the slightest trace of butane mix residue.. thats fine for some people.. me personally. i use cannabis as a medicine, and thc is not even the tip of the medicinal aspect of cannabis, which is why i use iso extract.. using 91% iso will help keep the chlorophyll out. 99% tends to strip more. whoever posted a couple posts ago relating to iso as to why its powdery.. maybe u arent filtering it properly. should be putting it thru at least a couple of coffee filters when u strain the alchohol after youve stripped off the cannaboid profiles. oh yes the reason why iso extract is more medicinal is because it takes all the cannaboids, not just thc. so bho is if you are just trying to get high, iso is for medicinal uses. i personally add the alcohol in a mason jar with the product im using.. do a 15 second gentle turning/shake, then strain it thru a strainer, then once i have mostly just liquid, ill put that through at least 2 coffee filters, then just let it air dry outside with a fan blowing on it for 12-24 hours, until its all gone, dont worry about what it looks like while its drying, sometimes you will see milky looking liquid its just water.. when its completely dry, you will have a nice layer of oil on the bottom of your pyrex. dont heat it, just scrape it together with a razor and itll ball up sort of in the center. it does not crackle or anything, just a clean melt.