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Darkening / "bluing" brass?

Posted: Fri May 10, 2019 7:39 am
by Benjamin Maggi
I have a small gauge 1 live steam engine that uses sprockets, gears, and chain... all of which are brass. I don't want to stand out as shiny, but paint likely wont stick to them (especially after they are greased and the engine has been run a bit). For steel, gun blue would probably be perfect. Is there anything that might work for brass that won't readily flake off or add much thickness to the parts but which will tone down the shine?

Thanks.
BAGRS steam engine.JPG

Re: Darkening / "bluing" brass?

Posted: Fri May 10, 2019 9:52 am
by Greg_Lewis
Brass black. Birchwood Casey is one source, avail. at sporting goods stores that sell firearms or sometimes Walmart.

Re: Darkening / "bluing" brass?

Posted: Fri May 10, 2019 10:10 am
by squandt
If you can not find it near you try Brownells.com this is the largest supplyer gunsmith supply,they have all kinds of stuff to color metal.

Re: Darkening / "bluing" brass?

Posted: Fri May 10, 2019 10:41 am
by Greg_Lewis
BTW, to get good results with the brass black, your parts have to be beyond clean. Any slight contamination with oil or fingerprints or whatever will affect the result. Degrease with whatever you like, follow up with acetone and fresh paper towels, using rubber exam gloves to keep your skin oil off.

Re: Darkening / "bluing" brass?

Posted: Fri May 10, 2019 10:47 am
by Rwilliams
I work with brass and bronze all of the time at the local railroad museum. Sure, the new fresh turned metal looks nice but the curator likes to see the patina of age on new parts. I now use sulfurized cutting oil during the final turning and finish work of the parts in bronze and brass. It is like magic how fast the darkening of the surface will happen. Starts to be visible in less than an hour and after a week or two, the part looks at least a year or two old. The metal art people use what is called Liver of Sulfur for the same effect and probably pay more for the same exact result.

Re: Darkening / "bluing" brass?

Posted: Fri May 10, 2019 11:20 am
by Benjamin Maggi
Thank you all for your advice!

Re: Darkening / "bluing" brass?

Posted: Fri May 10, 2019 12:07 pm
by makinsmoke
But that’s such a pretty little thing!!

Re: Darkening / "bluing" brass?

Posted: Fri May 10, 2019 7:28 pm
by Tim B Guenther
If you can find the chemicals; "liver of sulphur" (potassium sulphide) in salt form mixed with water will produce a brown color. Dark black - 2 oz. liver of sulphur, 1/4 oz. aqua ammonia in 1 gallon of water. Bluish black - Barium sulphide in water. Reddish brown - copper sulphate and water. Antique green - 4 oz each of copper nitrate, calcium carbonate and ammonium chloride in 1 gallon of water. My old jewelry books recommend these solutions be used hot. I would suggest doing this out side as many of these chemicals are toxic. Take appropriate safety precautions.

Re: Darkening / "bluing" brass?

Posted: Sat May 11, 2019 8:30 am
by BAdams
Tim B. - is the book you are refering to "The Complete Metal Smith" by Tim McCreight?
My high school jewelry teacher gave me that book as a graduation gift. Lots of great info in it.
I was about to thumb through it for the patina recipe until I saw your post.

Brook

Re: Darkening / "bluing" brass?

Posted: Sat May 11, 2019 2:43 pm
by LVRR2095
If you do nothing....it will acquire a patina by itself in no time.

Re: Darkening / "bluing" brass?

Posted: Sat May 11, 2019 3:45 pm
by Harold_V
Machinery's Handbook offers methods for coloring metals, including brass and bronze.

H

Re: Darkening / "bluing" brass?

Posted: Sat May 11, 2019 7:07 pm
by Tim B Guenther
BAdams wrote:
Sat May 11, 2019 8:30 am
Tim B. - is the book you are refering to "The Complete Metal Smith" by Tim McCreight?

Brook
The book I used for the recipes is "Metal Techniques for Craftsmen" by Oppi Untracht, c 1968 by Doubleday & Co., Inc.