>>565340Not sure of all the science-reasons behind it, but here's my story:
I don't sweat an extreme amount and don't generally stink. I wear a cotton t-shirt under a work shirt every day to work. After a few months, the t-shirts get those yellow pit stains, and after a few more months, it gets thick, like a fucking crust. It doesn't smell, but it's still fucking gross. After maybe 6-8 months, my work shirts (which are black) start to get the stains (white) and the crust, but it's almost undetectable. Then if I start to get really hot and/or sweaty, the work shirt will smell, but not the t-shirt. The t-shirts are just white cotton and the work shirts are some rayon/poly/cotton blend bullshit.
Anyway, after 28 years on this earth, many spent with yellow pit stains on undershirts and an older sister who had the same problem, I decided to try a deodorant instead of a deodorant/antiperspirant because I read that the aluminum in antiperspirants can cause the pit stains. I'm a few months into a new batch of t-shirts and happy to report no stains or crust and my work shirts are the same.
tl;dr - I feel like synthetic shirts can hold smells and I think it's because of antiperspirants. But some other detergents may help, as other anons have suggested. Ditching antiperspirants may also help cotton and other materials from getting stained/crusty.
