I realize this is a necro post but I felt there was something I could add, should anyone cruise through old threads and read through them looking for information. There are a lot of good tips already for removing the rust so I won't get into that.
After I remove rust from tools and stamps however, I use Birchwood-Casey Super Blue or Birchwood-Casey Perma Blue to seal the metal. It's touch-up bluing and turns bare metal dark blue or black but does keep it from corroding right away, provided you take care of your tools and don't leave them out in a damp environment to rust up again. You can get it from ebay, Amazon or any number of gun smithing suppliers.