A pure PG mix will produce VERY little visible vapor on exhale - if you puff and blow the cloud will appear and stick around for a second, but after inhaling it into your lungs and exhaling theres barely anything showing, it looks sort of like foggy breath on a cool (but not cold) morning. Extrudes a few inches past your mouth and dissipates almost instantly. I've found you get a slightly reduced
throat hit without the glycerin though, so you'll probably want to bump the nic concentration a bit to account for that. Use TW's PI or blip labs stuff for a pure PG+nic solution to mix. For the record, I haven't used TW's, only the blip nic+pg solution, but TW say's that their platinum ice mix is nothing but nic and pg, so it should be the same.