[Ol' Bob]

I have seen even fruit juice eat through stainless. I write it off as an impurity in the steel, as it happens in just one tiny place over a large, otherwise, unaffected area.

I believe that lamp black/carbon black is still the main black pigment over the ages. The best pigments of most colors are the ones that endure over time. Since a few molecules go a long way when spread only a molecule or two thick, I'd think those batches of dye long lived when doing surfaces other than fabric.