sorry to be resurrecting an older post but i tried this yesterday and today and my experience was similar to ITNinja's. i also have a DBV, and make a glycerin tincture out of medium-brown ABV and kosher USP food grade vegetable glycerin. i also clean my wands and grinders with everclear and add that to make up about 20% of the volume. sublingually, it takes about two full droppers for me to get a heavy body stone with some lighter mental effects.
with the DBV standard wand 1/4 - 1/3 full and lightly tamped, i start at a low temperature and vape until the aromatics are all gone and it's good and dry, then stir/crumble and re-tamp the wand, put a single drop of the tincture on top of the herb, and turn the dial up to my sweet spot. i've experimented with up to six drops, but one or two per bowl is enough. more drops = a more stony high, couchlock, red eyes, etc. as expected. i've been trying this through a variety of bongs and bubblers; glycerin is water soluble so results will probably vary without water filtration. the first thing i notice, even at low temperatures, is thick, billowy clouds that seem to absorb very fast. there's an aftertaste like overripe apples, but it's not unpleasant. in the wand, the glycerin gradually melts and disperses until it's well-mixed with the herb. as ITNinja said, it hits you fast and strong, and it's long-lasting. it's the kind of full-spectrum high i had been trying to get by vaping at higher temperatures, but using lower temps where combustion isn't a risk.
what VWFringe said about the droplet size of vaporized glycerin being too large to enter the alveoli confuses me, though. if that's the case i'd expect to be exhaling the same dense vapor cloud i can see building up rapidly in the bong, but there's almost nothing left after holding for about ten seconds. i don't have any experience with e-cigs so i don't know how fast a vaporized glycerin tincture normally absorbs, whether it be a throat hit or deep in the lungs. however i know this is working as my high is much improved, so the extracted cannabinoids in the tincture are definitely being utilized.
acrolein formation is the biggest concern i have with this method. i tried putting a drop onto a full trench in my MFLB (also water filtered) and unfortunately did heat it enough to produce some acrolein. i knew right away because the taste was horrible, and not like anything i've had come out of the DBV. success is probably going to vary by model, and i'd be careful trying it with any vape that gets too near combustion temps or doesn't have some method of temperature control other than your breath.
i hope some other people try this out and report their findings. considering i make about 4 fl oz of tincture per batch, i'm excited by the possibility of using it - very effectively - at a rate of only 1-2 drops per session.
I'd just consume it lol.
I had a correspondence once with a tech from a major ecig manufacturer and they claimed that the coils in the atty were getting hot enough to vape the nic. This was in response to me asking the same thing you did, I didn't believe that the atty was getting this hot. They responded that vg produces so much vapor, and nic is so potent, that you are certainly getting the coil that hot, it's just a tiny little heat source compared to something like an iolite. At the same time, I have seen video's where people use the iolite to vape vg based ejuice. Now they could be vaping the VG, and leaving the nic behind, or the vg could be acting as a carrier somehow for the nic.