Co2 oil. The consistency is perfect for rolling buds in. You want dense solid nugs only, dip them in the Co2 oil, if the oil is too solid, give it some heat by placing it in a Pyrex over a heating element. Now get your kief or I use grinder hash into a fine podwer. I take all the dipped nugs and drop them in a tub ware full of the hash. Shake until fully covered , then dip back into oil then once more into another thing of cleaner BLONDE hash/kief. The key to making it look nice if your oil, or needs to be clean or you end up with nasty looking nugs and terriblly harsh smoke.
Yup, Pete used dark oil and we didn't experiment further to see if we could make it purdier, but suspect the harshness has more to do with burning hash oil. If you light a blob of it, or heat it to combustion in a test tube, it gives off heavy phenolic black soot.
I originally coated the inside of my rolling papers with a film of oil, and while they were potent and effective, they left most brothers and sisters coughing. I once took a cannabis soap and lotion making class and at break passed one of my infamous hand rolls, which at one point had all 12 of the tokers, which included the instructor, coughing at the same time.
We were all medical cannabis patients, and one of them noting the coughing, reflected out loud, "Let the healing begin!"
These days I only vaporize concentrates and point out that in addition to the soot, combusting terpenes creates free radicals and carcinogenic byproducts of pyrolysis. It was also giving me chronically congested bronchial tubes.
While killer bud, rolled in killer oil, coated in pristine full melt kif has nice curb appeal, ours was harsh enough that we never tried to refine the process, and as I noted, have given up combusting it.