I've never had a problem with the color of padouk fading. I've always used nitro on it, but I doubt if the finish provided any magic. Sand it and seal it at once. After polishing keep it in a case when not in use, just as a precaution. Long ago I hung a raw padouk instrument by a window for quite a long time. The window side turned a lovely brown that wouldn't sand away, and the rest stayed red. It was fairly subtle, and no one else ever noticed. I don't much believe in magic wood, but padouk has always made wonderful instruments for me. Oil finishes will spoil padouk almost instantly.