As I've said before, patina experiments don't always turn out the way you want them to. When using vinegar, the acid will eat into the metal if left long enough -- and it doesn't etch evenly as an etching fluid would, but createds a pitted surface, which can be great (see e.g. this post). But sometimes it goes plain wrong.
In this case I sacrificed a plated stamping. I'd bought it ages ago, but never really liked it once I got it. Didn't like how she puts her chin out, which made it feel like she had the mumps or something. So I wasn't worried about putting it in the baker's ammonia and vinegar sawdust: a good patina would just improve it, a failed patina wouldn't damage a piece of any particular value to me. So in the jar it went. I waited. And waited. Even forgot it for some time. And very little happened. Often, the vinegar will eat through sealants and even plating, but not this time. In the end, I put it in another jar with just salt and vinegar to see if that would speed up any patina. Eventually, this is what I ended up with.
More rust than verdigris and the edges had corroded badly. That distressed, rustic surface might be a great loook on many stampings, but perhaps not one with a human face because that protruding chin had become more etched and pitted than any other area.
I had ended up with a one-eyed bearded lady!