Oxpho-Blue™ may be the easiest and finest cold blue on the market. The
chemical works directly through the oil on a gun, removes any thin rust
and then blues the steel underneath. No after-rust. Great rust preventative.
Applied easily with a cotton cloth. Extremely durable.
I used this cold blueing agent to reblue a 1970's Sako rifle that my dad has been hunting with ever since he bought it brand new over 40 years ago. The blueing was very thin and non-existant over most of the gun. I found that metal prep was the key to getting good coverage and color from this product. I used steel wool to remove any rust and to rough up the old blueing and rubbing alchol to degrease the metal. The metal must be very, very thouroghly degreased or else the blueing will not react with the steel. I also found that it helped to stick the metal to be blued in the oven to heat them up to temperature that was just good and warm but still comfortable to handle. I found this worked best on bare steel and was rather splotchy when you tried to go over the original blueing.
I have been using this product on black powder pistols and rifles as both a touch up and for complete blueing jobs. It works well as long as the surface is very clean and roughed up with 600 grit paper. Wetting the 600 grit paper with the chemical and gently sanding the metal works best. You need to keep the sand paper wet, don't let it dry out or the blueing will streak and you need to go slowly. . Even after blueing you still need to keep the metal oiled but that is because it is a cold blue chemical. It also works on some of my WW2 rifles for touch up on the butt plates and other wear areas.
Yes: I said do it right the the first time. I have used a lot gun blueing over the years..But this is by far the best !Give it a chance like I did and you want go wrong...