Any special instruction how to apply so the black doesn't come off?
My experience is with Max Black for base metals – in this case,
more (time) is not better. If I gently agitate the jewelry piece in
the liquid for a few seconds (until it has gotten at least dark
brown), and remove it to the rinse water, all is well. If I leave the
piece in the liquid for a longer time, it will flake off.