When I first read this thread, I remember thinking of several times that I had unexplained, persistent spots that would sting a bit on my tongue (near where my mouthpiece would be when I vape) and in the back of my throat. It made sense that I may have had bits of silica thread embedded, to some degree, in those spots. I should have known, as I worked in a fiberglass factory for 1.5 years in my past, and the sensation was a somewhat familiar one.
I now believe that I had one embedded in my lip for the past two months or so. I've been using mostly cotton and bamboo in that time, but I occasionally use factory-built ones, still. Shortly before that, I was using stock fluxomizers (CE2s) with the narrow rubber mouthpiece, and I eventually noticed that my habit of putting the tip just between my lips caused my upper lip to be burned a few times, presumably by hot liquid spitting out the small opening.
I adjusted my technique, to make sure that the opening was past my lip, and not too close to my tongue. Around that time, I noticed a small light spot on the bottom of my upper lip, about the size of the opening of my mouthpiece, right where my mouthpiece would rest when I vaped. At that time, I thought it was just a burn. Later, when it didn't seem to be healing, I thought there may have been scar tissue there.
Just the other day, though, that spot formed into something like a small boil, and then it occurred to me that I must have something in there. I've never had anything of the sort in such a place on my lip, before, slightly to the back of the bottom edge of my upper lip. I decided that since it was 'coming to a head', that I'd best try to rid my lip of whatever it was.
I guess the squeamish folks can skip this
paragraph.
A couple of pin ......, and some carefully positioned squeezes, netted me a very thin, approximately 8mm long extrusion semi-solid pus. I was a bit surprised at that. I did a cursory search of it, not expecting to find anything, and did not. My lip has almost returned to normal, now, about a day later.
So, I can't be sure that it was a silica shard, but it's the only thing that makes sense to me. I'm now even more wary of silica fibers.