Maybe the plastic of the bottle flexes more, whereas glass doesn’t move, so the cap scrapes against it more.
Comment on More microplastics in glass bottles than plastic: study
Teal@lemmy.zip 3 weeks ago
They say the glass bottles have plastic caps and that’s the source for this type of container. I can’t understand why those same caps on plastic bottles have less contamination.
Are the caps lined differently on the inside when dealing with plastic or glass?
bramkaandorp@lemmy.world 3 weeks ago
stink@lemmygrad.ml 3 weeks ago
Reading through it, I assumed that the glass bottles have metal caps, with plastic paint?
It makes sense to me, sorta.
Inside of the cap has a plastic coating to deter corrosion from the acidic drink. And I’m assuming that on the assembly line the caps are face-down, so the metal from the top of one cap is scraping the plastic on the bottom of the other cap. Then it leeches into the drink over time?
SolarMonkey@slrpnk.net 3 weeks ago
My guess is the shape of the cap, and maybe even a bit to do with the material (ime pop-off caps are a weaker plastic to allow them to deform around the bottle lip). Screw top plastic bottles have deeper caps than pop-off glass bottle caps.
Thus when stored the inside surface of the pop-off cap has more chance to rub against other surfaces and create plastic dust, and being a weaker plastic it may gouge more easily as well.