Timely post for me. I just started flying some on-demand 135 in a Citation andjust last week bought a couple of shirts from pilotshirts.com (60% cotton).
I'm a lawyer and all my other shirts are 100% cotton. I believed pilotshirts.com's website when it said that there are no 100 % cotton pilot shirts. So, now I'll check out Landerwood and crewgear. Was planning to get a couple more shirts soon, anyway. This sort of info is useful, even if I do end up staying with pilotshirts.com. Thanks.
P.S. I just went to their websites (Landerwood & crewgear) and appears to me that all of the shirts are 60% cotton. Maybe I'm missing something. I'll check again later.