using gun bluing on brass (w/pics)

D

DIY_guy

New member
Yes I know there are products dedicated to blackening brass parts but I had none on hand but I do have an awful lot of gun bluing chems on hand so I thought I would give it a go. None of the bluing companies will tell you the exact recipe and proportions of chems used and because all of them said their products would only work on steel I tried a little test on other metals. They were correct to a point. I was however impressed with their ability to blacken brass. (some more than others) Restoring some really old guns requires brass blackeing and while there are products one can buy to do the task, after seeing how well some of the gun blues worked on brass I don’t feel the need to buy a separate product for the job. Clearly these products all have a different recipe and varying amounts of sulfides and acids and oxides as they all performed diffeently on steel and brass.

Here is the line up of bluing agents I have on hand including aluminum black

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I used a piece of brass bar stock I had in the shop that I use in knife making projects. I cleaned and buffed the test area and then applied all 7 products. Some were quite harsh to the brass and some not so much. Some really darkened the brass and some not so much but rest assured all of them did blacken brass.

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Then I used steel wool to abrade off the blackening. It took some effort but all gave up the coloring but then brass is a very soft metal and steel wool is much harder so it was no surprise. I was pretty aggressive in abrading the brass and was impressed with how well they held up considering they are not meant as brass blackening products. Then I went a little nuts since I was looking for more brass to sample. These were done with Oxpho-blue as I found it the most effective on brass (the most black). The G96 was the most caustic and damaging to the finish of Brass. It deeply etched/pitted/damaged the surface of the sample bar.

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If you find yourself in need of blackeing brass and dont have any brass black on hand, you can substitute gun bluing.
 
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I used Numrich Arms' Formula 44-40 liquid cold blue on the brass parts of a T/C Hawken to achieve a mottled CCH look, than turned out very handsome.


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Hello, I recently purchased some of the agent you used in the photos. my results were not so spectacular. I was wondering how you did this? did you soak your brass then polish with 000 steel wool or something similar? I hope to hear back. Thank you.
 
Perhaps the good results are from his cleaning and buffing the brass. In metal finishing preparing the surface is the key to success. Try cleaning and degreasing your metal after polishing or sanding and wear cotton gloves to keep the oil of your skin from the surface.
 
The secret is cleaning.
I use Acetone or lacquer thinner, or even a soap cleaner like Greased Lightning or kitchen cleaner.
I then give the part a good flush with 90% alcohol and warm with a hair dryer.
Over heating doesn't help, it hurts so don't use a torch.

Depending on the size I may apply the cold blue with a Q-tip or dip in the bottle.
I don't like dipping because this contaminates the bottle of cold blue and after a time ruins it.

I find that gently rubbing with the soaking Q-tip helps.
After it's blackened, rinse with hot water and wipe with a soft cloth.
Cold blue works surprisingly well on brass and copper.
 
The twentieth edition of Machinery's Handbook has a couple of pages on coloring metals including brass, blackening brass on page #2265.
 
Wish there was a good way to blacken silver braze. From what I have read, products used to blacken silver braze will damage the bluing on the surrounding steel.





 
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using gun bluing on brass (w/pics)
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That is not what I did, for the worst of case I use vinegar for a maximum of 15 minutes for the life of the case. It is what I did before that turned cases black, that was berore I found vinegar was easier to get, cheaper and safer to use.. I had cleaning time down to less than 2 minutes and rinsing in boiling water was mandatory, two times. When finished the cases came out black.

F. Guffey
 
Just out of curiosity: is there any practical advantage to bluing your brass?
I mean, other than aesthetics, one may think it'd help keep your brass from staining, but besides that...?:confused:

Sure looks cool, though.
 
Cold bluing works much better on brass than steel.

Arquebus- you should be able to darken the silver solder with cold blue wihhout damaging the bluing, if you are careful.
 
Deariswheel,

Do any any of the degreasers damage the integrity of the brass? That may be the issue. Will the cold blue damage the brass if I let it soak for a few minutes?

how do you polish it up afterwards? tumbler or do you have to hand polish?
 
Yes. The Oxpho Blue used should work on both. It is phosphoric acid-based. Avoid hydrochloric acid-based blue at all costs. The chlorine weakens brass and steel.

I have used a number of chemical blackening agents on different projects and found that if you dilute them in distilled water 1:3, you reduce the aggressiveness of the acids on more reactive metals, like the zinc in brass. Dilute it and submerge the brass and use a retired toothbrush as an applicator and keep brushing all over until it is done.

I've found coloring brass cases is a great way to lose a larger number of them in the grass, but if you had some load it was critical to identify as unusual in some way, it will work.
 
Arquebus- you should be able to darken the silver solder with cold blue wihhout damaging the bluing, if you are careful.
__________________
Bill DeShivs, Master Cutler
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Thanks. I have tried Oxphoblue and it has no effect. That really isn't silver solder, It's silver braze.

Silver solder is mostly tin with a very small addition of silver. Silver braze is typically about 56% silver and is worked at 1200 degrees F (dull red). Also pretty expensive.

 
Back when I was smithing silver-soldered (I know...I know) front sights and Ed Brown mag wells were all the rage.

We used Brownell's Silver Solder Black to cover the silver solder line. As soon as the slide or frame came out of the bluing tank we'd take it to the side, and use a toothpick soaked in silver solder black to turn the silver solder black. As soon as you had enough coverage we'd hit it with Break Free.

I understand Brownells no longer sells this stuff, which is too bad. I also hear that you can buy the same chemical at Art Supply stores like Black/Ultrecht that will do the same thing- blacken brass.
 
Brownells still carries it, but it is a nitric acid and selenic acid mix, according to the saftey sheet, and those are also the ingredients in 44-40 blue, IIRC. The phosphoric acid based Oxpho Blue is better on corrosion resistance, but it's not as black, and if it doesn't work on silver solder, I'd forgotten that. With 44-40 you get darker color, but I have had after rust with it and other non-phosphoric acid-based cold blue. The solution to that is I spray a highly penetrating and alkaline cleaner on the blued spot to penetrate and neutralize any acid traces (I use Formula 409, but there are others), rinse that off in boiling water so the heat self-dries it, and then I apply LPS-2 which penetrates and adds rust inhibitors.
 
Cauiion; bluing is corrosive

I have been restoring Hickory RamRods, for sidelocks and applying bluing to the new tips, in order to give them an artificial aged patina. So far, I have never found a bluing that "doesn't work. Currently using an old bottle of Outers bluing as well as 44-40. A word of caution on letting the bluing come in contact with the wood as it will eat the wood. Washing the finished product is important. .... ;)

Be Safe !!!
 
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