From what I have seen, not really. It seems like it's a combination of the lume and the metal blackening and oxidizing. The only way to effectively salvage the hands was to strip and relume them if the metal hasn't deteriorated too badly. If it has, then replating and reluming. Obviously, this is an unusually oxidized example, but you can see where the blackening appears on both the lume and hands.Can anything be done to halt this once it has started to appear?