Birchwood Casey Super Blue Liquid Gun Blue, 32 ounce (quart)

Double-strength blueing solution
For blueing highly polished steel parts and hardened steels containing nickel and chrome alloys (except stainless)
Super Blue Extra Strength Gun Blue is the blackest blue

A double-strength blueing solution designed for blueing highly polished steel parts and hardened steels containing nickel and chrome alloys (except stainless)
Super Blue® Extra Strength Gun Blue is the blackest blue
Use caution to confine the solution to the area to be reblued, as it will have an effect on the existing blue.