I have been vaping using my SSV whip vaporizer for a few years now, and I love everything about it. I honestly haven't smoked by myself once since then, only using combustion when I am at a friend's house (and even then, I got most of my friends on the vaporizing bandwagon). I use my SSV almost every day and it's amazing, but I have been thinking recently about the efficiency of my hits. Obviously, any visible vapor when you exhale is wasted THC that is not making it into your bloodstream, and the SSV gets me some extremely big hits. I tried holding my hits in for longer, but it doesn't seem to make a difference beyond 15 or so seconds. I have tried holding my hits in for up to a minute, and the only difference I feel is lightheadedness due to the lack of oxygen. A couple times now I have experimented by exhaling my first few, more potent hits into a plastic bag, then taking my next hit from that bag. I got this idea from Harold and Kumar in that scene where Kumar smokes for the first time by having that girl exhale her smoke into his lungs. I still get visible vapors after the second hit, and it's just as potent of a feeling. I imagine you could do that a few more times and still produce visible vapors on the exhale, but I haven't tried that. My question is, has anyone else done this? I realize it's the same concept as a bag vaporizer, but I'm more wondering about the high amount of carbon dioxide from my lungs that is mixed in with the vapors. I don't think it's a big deal or will have any negative side effects since carbon dioxide is only bad when it replaces the oxygen in a room, but I thought I would ask the people who are most likely to know about this. Also, if anyone has any ideas on making this method even more efficient, I would love to hear them. BTW, I do already revape my bud multiple times after its initial go, in case that was going to be someone's efficiency suggestion.