Tyvek - paper or plastic?
short answer: plastic.
not "kind of plastic," not "paper-like material" - just plastic.
I know why people call it paper though. it looks like it. folds like it. you can print on it, write on it, whatever. so people just go with "Tyvek paper" because it's easier than explaining it every time.
but yeah, technically it's HDPE. same family as those plastic milk jugs. just made into really thin fibers and pressed together so it feels different.
where people get it wrong
recycling.
this happens a lot. someone thinks "oh it's paper," throws it in the paper bin… and that's not right. it's #2 plastic, so it should go with plastics.
not a huge deal if it's one piece, but still - if you're trying to be accurate, it matters.
why people use it anyway
because it's tough.
like, you can try to tear it and it just won't go.
it keeps water out but still kind of breathes.
and it's really light for how strong it is.
so yeah, for stuff like tags, packaging, construction wrap - makes sense.
my opinion
if it's just a cheap flyer or something temporary, just use normal paper. seriously.
but if you need something that won't fall apart, Tyvek is solid. just don't call it paper and confuse people.
that's pretty much it.