Hahaha
I usually 'freebase' it off a charcoal used for burning resin incense, with a glass slide, just like a crackhead, they call it hippie crack for a reason.
As far as making light oil...
It really has a lot to do with having good trim only, not ground fine, to maintain the solid glands.
Mids make a black tar no matter what because of degradation.
It's best to make oil right after harvest, after they've got the the first dry stage, trim off trichrome covered leaves for making oil, the jar and cure *the bud.
A lot of people wait and make hash later out of old trim, the fresher the better.
It really has a lot to do with quality though, old dank still makes light solid oil.
Also stir out the bubbles as the butane is evaporating, I imagine there's a thread that has all this crap on it, I was self taught from a growing book's supercritical fluid extraction technique, then trial and error...
Also don't grind to much... Important.