Do any of you have a problem with hair collecting in the armpits of your sweaters? Do you do anything to prevent this from happening? I wonder if your hair has to be some minimum length before this happens. So, when answering this question, if you could indicate your hair length that might be informative (especially if you noticed a difference with hair length).
I've never had the problem, but my hair is only about half as long as yours.
Did you mean hairs that have been shed collecting in the armpits, or hair that is still rooted in the scalp?
Mostly hair that is shed. A hair tends to travel in the direction of its root because of the orientation of the scales, so I think attached hairs tend not to get snared this way.
I almost never wear sweaters. They pull my hair too much and make a mess of it whenever I take them off. I do wear T-shirts because they're the bottom layer and thus not apt to come off during the day, but anything above that layer I prefer have buttons or a zipper.
Bill