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I just completed a custom designed scope mount to be used on a Model 71 Winchester. Its made from carbon steel. When finished it will get ConeTrol rings. Design uses the barrel dovetail and the factory peep sight holes for mounting. No mods to the rifle other than removal of the dovetail filler and peep sight screws.
I want a descent bluing, but never did rust or hot bluing in my shop.
Was wondering if I would get a better and more durable blue if I heat the part to around 250F then apply Oxpho.
Any thoughts.
Bob Nisbet
email: [email protected]
 

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The Troll Whisperer (Moderator)
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I've always found that carbon steel will take the cold bluing much better if the metal is warmed prior to applying. Can't say what temp should be applied, just that I try to get it warmer than being able to hold with the bare hand.
 

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No need to go that hot. Just use a heat gun to where the metal is nice and warm to touch. Make sure the metal is CLEAN. The trick is to apply with some degreased 3/0 steel wool--seems to activate the chemical. Also don't dip from the bottle, it contaminates the chemical. Buff with clean 3/0 or 4/0 steel wool.
About the third application you will notice that the color is nice and even and you're not getting any more chemical action. Wash the metal, dry, and oil. Here endeth the lesson. Goatwhiskers the Elder
 

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250's way too high. Warm to the touch is all you need. Anything more and it seems more likely, to me, to end up blotchy. And despite the fact that it will work even on a surface that has not been degreased, go ahead and degrease thoroughly. Apply is repaetedly, buff with 0000 steel wool between applications. It sometimes takes many. many, many repititions, but you can get a good looking and fairly durable finish with Oxpho.
 

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Oxpho blue is a form of phosphatizing, like Parkerizing. All the phosphatizing processes are done in water solutions that are below the boiling point. They have optimal temperatures that range from about 150 degrees to about 190, depending on the particular chemistry. Running cooler gives a thinner, finer coating, while running warmer gives a thicker, more matte result. I assume this would be true for Oxpho blue, as well.

Since the Oxpho-blue chemistry is formulated to work at room temperature, I would not heat the work unless I were going to dilute the product first. I have used cold blues diluted up to 4:1, but only at room temperature and only to slow the process to allow the coat to build without making gas bubbles that loosen portions of the finish. That said, a number of people do apply heat after the blue has appeared to help set it. I recommend you take some scrap steel and try any of these process alterations before actually trying them on your gun.

The advice to rub Oxpho-blue in is good, but realize the steel wool will consume some of the chemistry (unless used after applying the blue, as Pisgah described). I have had good success applying cold black to aluminum with an old toothbrush, which constantly removes loose surface color and puts fresh compound on the metal it exposes. You might experiment on scrap steel with both carding items to see what happens? Perhaps the color will be better with the degreased steel wool? I've never tried it with a cold blue, but do use it to card rust bluing between steps.

Rust bluing is slow (takes about a week to go through enough cycles to get solid color) but not difficult. You would need a water pan large enough to boil the rusted parts in to convert the rust from red to black, and a source of distilled or deionized water for best results. Rust blue will look darker and bluer than Oxpho-blue, which looks more like dark charcoal gray to me. Rust blue will be significantly tougher. Wearing off a bit too easily is one limitation of cold coloring compounds.

Brownells sells their own brand of rust bluing solution that isn't too expensive, and they used to have a policy of sending a copy of their printed instruction sheets out free for the asking. You could call them and ask for that if the idea interests you? The other day a fellow told me he rust blues using Brownells Dichropan bluing instead of a dedicated rust bluing solution. He finds it rusts well enough on its own if it isn't rinsed, and he thought the final color was darker, but I haven't tried it.

Regular rust bluing is about the color of old Colt blue, and has a slight luster to it rather than a high gloss. It is very handsome.
 

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Brownells sells their own brand of rust bluing solution that isn't too expensive, and they used to have a policy of sending a copy of their printed instruction sheets out free for the asking. You could call them and ask for that if the idea interests you? The other day a fellow told me he rust blues using Brownells Dichropan bluing instead of a dedicated rust bluing solution. He finds it rusts well enough on its own if it isn't rinsed, and he thought the final color was darker, but I haven't tried it.
I'd bet that you can download them from brownell's website, I'd look, but its almost 1am and I'm just not that ambitious at this point :D
 

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There is another option on a part that is NOT heat treated, and that's heat bluing. Heat the part up- experiment with how much, but try 350-400 degrees to start, and wipe the hot metal with oil. You can get different blues using different oils, so, expect to experiment.
Heat bluing is far more durable than any cold blue, even Oxpho Blue.
Ever see an old SA Colt with beautiful bluing that was actually blue? That was done by heat bluing, using fish oil, or so the Colts experts say.
 
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