We have been in s.s. car wash business for many years. We started with Kalite frp. Over time it yellowed/ browned, even with cleaning with a mild mix of hydrofluoric every year. Other than the yellowing issue, it was a great product, easy to install with minimal wrinkling, loaded with fiberglass. It may now be treated so it resists UV yellowing. Next we went to Extrutech in both s.s. bays and in-bay automatics. Extrutech is, in my opinion, very good in the in-bay automatic bays, but we had a lot of problems with holes being punched in the Extrutech in the s.s. bays. We removed the Extrutech from the s.s. bays about 10 years ago and replaced it with Kemlite frp { not Kalite }. Kemlite had a UV additive and coating, thus it stayed white and is white to this day. It was more flexible than Kalite, thus more difficult for us to install with fewer wrinkles than Kalite. I don't know if these products are still available. or have changed in any way. This has been our wall covering experience.