Gary, Thanks for refreshing my memory. I knew I had read something about that. This appears to be something different than the other problem I was having. However, I also experienced this etching situation as you have described. I was helping my dad clean some iron a few weeks ago, and we left like five pieces in over night. One of them was a griswold scotch bowl, which in the morning, looked like hell >:(. There were several areas that had this etched effect. Quite rough feeling and shiny, as if some surface metal had been removed. Also the bail had become lumpy all over, like it had partially melted or something. I'll try to get a picture soon. Recently, I've also sometimes noticed when cleaning four pieces at once, that maybe 1 or 2 will be nicely cleaned, while the others have hardly cleaned at all, or may have red lumpy rust forming in places. That seems to clean off, but it don't seem right. I may have to reconsider cleaning multiple pieces at the same time.
Ed, I was wondering if that could be the cause of the darker areas. Seems logical to me. I may have to try the wire brush in my drill. Might help blend the discoloring. Always thought it might lighten the surface color too much, but it's worth a try
ET