I found this about a month ago and was able to get all the crud off of it using water and a toothpick. Any ideas on how I could get it back to a nice brass/copper look without harming the item?
Looking at used saxes for my son I ran across what is known as "red rot." http://www.brassarts.com/about_red_rot.htm I can only assume it affects coins as well as brass and copper instruments.