You're talking about those ones made of glued-together cork chips, right? They're only vaguely natural, and it wouldn't surprise me to find out they're shedding all sorts of who-knows-what. I've not tried melting one in the microwave, but ewww. I think I'd rather buy wine with a metal cap - the supposed "breathability" of a cork only matters (to the extent it does matter) for wine that will age a long time, which isn't anything I do.
It would surprise me to find out that the traditional, straight-from-the-tree kind need adhesive to stay in the bottles. I mean corks have been used to stop bottles for hundreds (thousands?) of years; surely they didn't use glue all that long ago?
I suppose - to supply a speculative counter-argument myself - it may be more profitable to cut the natural corks X% smaller, and counteract the mechanical deficit with glue. (That's, uh, kinda typical of the world we live in.)
I’m French and never saw the metal cap but surely it seems perfect for the non aging one. However tradition plays a big role - even if there’s better modern caps.
Regarding the pre modern chemical techniques: not an expert but it seems people used to drink younger wine back then, and used wooden barrels or clay amphora for the older times. For in between times (and the amphora) solid cork as you mentioned seem very plausible.
Considering the material deficit: consider that when you do the microwave cam cooking, the cap double in size and don’t fall down in many small parts. It’s so big it’s basically impossible to put it back inside the bootle. My 2 cents hypothesis is they use glue to use more cork and have a better sealing, enhancing the conservation.
It would surprise me to find out that the traditional, straight-from-the-tree kind need adhesive to stay in the bottles. I mean corks have been used to stop bottles for hundreds (thousands?) of years; surely they didn't use glue all that long ago?
I suppose - to supply a speculative counter-argument myself - it may be more profitable to cut the natural corks X% smaller, and counteract the mechanical deficit with glue. (That's, uh, kinda typical of the world we live in.)
Can anyone out there speak directly to that?