I've had excellent results using alum. I suggest putting the crown in a shot glass with water and as much alum as will dissolve in the water. It works best (fastest) if you can apply heat to it. I use the hand-bluing heater that was described in this forum several years ago, but a hot plate would work well. It should be warm, but not boiling. When the alum is working, you'll see small bubbles coming up from the steel.
Posts: 366 | Location: Illinois in the USA | Registered: November 17, 2011