I don't know that it will. It should as that is how the green color is achieved in the first place. Parkerizing comes out of the tank in various shades of gray. Then if you want the greenish color you apply cosmosline. If you want black you run it through the bluing tanks. If the parkerizing hasn't scratched completely off there's a real good chance that the cosmoline will color it. Then again it may not but that's what I would try. George