Convert was an inappropriate choice of words. I should have said that the silver is replaced by the noble metal. Another possibility is that the noble metal simply encapsulates the silver.
Originally Posted by cjarvis
One would think that the exact nature of what happens in toning would be known but it apparently is not as there has been very little modern research on toning with gold, palladium and platinum. I exchanged correpsondence last year on this subject with a number of persons who know a lot more about this subject than me and the bottom line is that the reactions are fairly complex and not well understood.