Here's Chuck H's Greying recipe - a pass of rust blue then ferric chloride etch. It's just what I was shooting for, a soft grey. The metal was highly polished before starting. I think some of the old rust freckling shows back up after the etch, as it was hidden by the polishing. Not a big deal, just a 'note to self'. I cut the Radio Shack etchant by 50% with water.