It's probably been discussed, but I can't find the thread. I'm looking for advice on promoting rust on mild steel to make new steel more closely match rusted steel. One of my sculptures uses weathered (well rusted) salvaged steel for most of it, and a few pieces of new 11GA mild steel scrap. I have removed the mill scale (60 grit flap discs) and have left the piece outside in the rain. I know that over time it will match pretty well, but the piece is in a show in 3 weeks. Is there a way I can accelerate the rusting process?