I know the myth about SS not rusting, but I'm having an issues where after washing, a piece I was practicing on is now showing small spots of rust through the annealed (stained) section, ruining the anneal (stain). This was a piece that I slowly stained and there were no visible sparks. Any ideas on how to prevent it? Is it even possible? If this had been a customer item, I would be very unhappy with this result.