Update: I was cleaning my Kirby Morgan hat wrong for a solid decade
Honestly, I was using a stiff brush on the face seal for years until a diver out of Morgan City, Louisiana, told me over a beer that it was causing micro-tears I couldn't even see, and he was right because my next pressure test showed a tiny leak.
Man, that hits home. I once used a scouring pad on a helmet's spit valve because I thought it needed a deep clean. The shop guys had a good laugh at my expense when they saw the damage. Turns out you can be too thorough.