Eco friendly laundry/wash bags??

Hi, I’m 18 and trying to start investing in more natural fiber clothes! Because of this, I want to make sure they survive when I do laundry since natural fiber clothes can be more expensive at times :)

I’m trying to find wash bags for the laundry that have a zipper, but I’ve noticed that all the ones I’ve seen are synthetic materials. I’d like to find a wash bag that’s 100% cotton with a zipper or just a way to make sure it stays closed in the wash.

I’ve heard some people recommend to use old pillowcases so you don’t have to buy a wash bag, so I might look into finding an 100% cotton pillowcase with a zipper but I’m worried that my clothes wouldn’t get cleaned properly through the pillowcase.