I make glycerin tincture using both the cold and hot method. If I want to taste plant pureens and the subtle nuances of the bud, it is hard to beat bud and glycerin in a jar tumbling for 60 to 120 days.
You can also cut the cold process time in half by putting the jars in an ammunition case vibrator for a couple of weeks. It has less subtle nuances than the long cold process, but is still potent and tasty.
If I want a potent tasty glycerin tincture without the subtle nuances, I crank out a hot potion in a week that is stronger than a typical cold tincture and use only sugar leaf. I do that by bringing a jar 3/4ths full of pulverized material and covered with about ½ inch of glycerin, up to 160F in a hot oil bath and cooking for 30 minutes at that temperature.
During that time, I frequently stir the mixture using a wooden spoon. A metal spoon will work, but you are more likely to tap the hot jar too hard and crack it.
After thirty minutes, I take it out of the oil, cap and wipe it, and set it away to cool. The next day I set it back in the hot oil and bring it back up to 160F while stirring. When it reaches 160F with the oil at 200F, I take it out, cap and wipe it, and set away.
Hot cycling creates a pumping action that speeds up the process.
I do that for seven days and on the seventh day, I pour it in a bag I sewed up out of a high thread count bed sheet, and press it in a press I made out two stainless dog dishes, some scrap metal, and a hydraulic bottle jack.
It produces a sweet tasty tincture with no noticeable burned flavor, but alas no subtle plant pureen flavors either.
The best part is that if you take the pressed pucks from two jars and put them in one jar, fill jar with glycerin and stir in a hot oil bath until it is well broken up again, bring it up to 160F and repeat the process, you will get a second squeezing that will rival the first, though lower in volume. Depending on the material, I sometimes get three squeezings.
I have used bubble hash or kief, and use the same process as for the plant material, other than I only cook it one hour at 160F and decant it. You can adjust the potency pretty much to whatever levels you want with hash or kief, though I haven’t been able to achieve the potencies in glycerin that I have in oils and tinctures.
You can also bump up potency by running the glycerin through multiple batches of plant material.
Likewise, I have bumped up potency by first extracting the cannabis oil using alcohol or hexane, but glycerin is very specific about what it will dissolve and there has always been a lot of flocculant left over after infusion, which is difficult to remove and isn’t tasty.