Thanks all for your input. I agree with some and disagree with others. I have decided that I do like this product but it has its place. I'm not a gun dealer and don't indulge in the practice of deceiving people when I do sell one of my firearms so I'm not concerned about what applications I will use this product for. When I started this thread I knew absolutely nothing about cold blue because I have never used it. As for the claims of "pulling the old blue out of the metal" I was simply paraphrasing the claims of someone I know who bought it and the explanation he gave me. I wasn't there for the sales pitch he got so I don't know if it was explained to him that way or if he just made his own assumptions. Either way, no matter. I decided to come here and find out the skinny. Thanks again all.