I tighten mine without fear & have not noticed any cracking yet. Suspicious it is a batch related issue if it is fairly isolated.
While defects in caps could be the issue I doubt it. I think this is tied up with the 'my cap is jammed on so tight I can't get it off' problems? I suspect it's thermal expansion playing up. Specifically when hot the cap expands more than the glass? Tightening it more when hot (intentionally or otherwise) sets it up for being too tight when cool. This can 'freeze' the cap on and (since the threads in the glass are less precise and therefore don't take stress uniformly) or even introduce cracks by concentrating this force.
Evidence here is some guys have problems more than once, while most seem to not have them at all I think.
Unless you overstress it, the plastic isn't going to crack on it's own IMO. Even a cap with a hidden flaw. You need stress to exploit that flaw, warming and cooling alone are unlikely to do that. Remember the heat and subsequent cooling in making the cap are much more extreme than we offer in use.
Nice post Bravesst ... I've been wondering ( since my new digital scale arrived last week ) how much weight is lost from a proper "dry out" ... 1.01g / 1.08g = 93.5% remaining.
I find the same sort of results (less than 10% loss), however it can be much higher if you start with 'fresher' or 'really dank' herb. The stuff from the dispensaries is generally well cured, but slightly damp. I know great effort is made to keep it from drying further past a 'magic point', I've been told as much several times. I suspect to make it more appealing to potential buyers as much as the chance to sell you water at top shelf prices?
Key to us is if you don't remove that last 5-10% moisture before loading you'll have to do it in the vape before you get to the good stuff. And moisture in the vape not only slows down the fun but opens the door for fouling. OK, opens it much wider......
OF