At matches I always wear a common baseball cap. I almost never wear them anywhere else because I like the sun blocking offered by straw hats. The problem is the baseball caps gets sweat stained until it is too ugly and kind of gross to wear. I hate throwing out an otherwise not worn hat. We have tried every cleaner we can think off w/o success. We were concerned about whatever material makes the bill stiff but finally just dunked the whole hat in a bucket w/ some oxyclean stuff my wife uses on other things. Soaked overnight and then sat in the sun all day. Jeez, still stained. When we were at the beach, I picked up a couple of hats that are a light tan color thinking that might make the stain less obvious. Do you guys have any better solutions?