Yes, the cloths are reversible. As long as the cloth reverts back to the original goldenrod yellow color, it will continue to change when exposed to ammonia vapors. We aren’t certain of how many times it can be reused (it is somewhat dependent on the use). Eventually, it won’t revert back to its original color and can no longer be reused. It works best if exposed to vapors. If you get it wet, it will not be reusable.