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topic 4076

Brass plating is too yellow, need gold color



A discussion started in 1996 and continuing through 2020 so far.
Adding your Q. / A. or Comment will restore it to our busy Current Topics page

1996

Q. Can you recommend any particular brush plating formulas of brass plating solution? I have read in the Metal Finishing Guidebook that a formula of copper cyanide, zinc cyanide, and sodium cyanide plus a few other chemicals will work well, replacing sodium with potassium cyanide to yield a more gold color. Will this formula possibly work with brush plating or will I just have to experiment with it? Also, does brass plating yield a bright shiny finish similar to that of gold plating? Thanks.

Rob Henry - tech manager
Cleveland, Ohio


A. I have seen a bright, light colored brass plating that could easily be mistaken for gold. However, brass will quickly tarnish unless it is lacquered; it will not remain bright and shiny by itself. So you will be confronted with the additional problem of finding a lacquer that is robust enough for your application, while remaining very clear. As you will see from earlier discussions here about lacquering mag wheels, such a coating will probably have a very limited life.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha



1999

Q. We do Nickel/Brass Plating in an automatic barrel line.

The color of our brass is lemon/yellow.

Our customer wants a golden color brass.

Any suggestions on chemical composition to achieve a golden color brass.

Ed Esposito
- jersey city, New Jersey


1999

A. Good Morning,

Many years ago I ran bright brass to look like a gold finish. Cyanide copper / bright nickel [must be bright] to brass plate, just a flash over, with a "sealer" style dip afterwards ... finish very close to gold.

Hope this helps ,

Ron Landrette
plating equipment supplier - Bristol, Connecticut


1999

A. Dear Mr.Esposito,

After a long experience, I learned that the lemon/yellow brass bath is one of the most stable brass baths, except perhaps of the "white brass" solutions. Any attempt to modify this standard color of the deposit, by changing the concentration of some constituents, will result in unstable colors of the coating and many head aches. For automatic production there is no other solution. If your customer wants another tint of the deposit, you may choose between light bronze coloring ( antiquing )the deposit or applying a colored transparent solvent lacquer.

Depending of the nature of the plated objects, I think that the alternative to apply a very thin (0.06 - 0.08 µm ) layer of gold from an acid gold-cobalt bath, after nickel plating, is not be neglected. Apparently this is more expensive, but if you put in balance the cost of frequent analysis of the brass bath ,of the passivation and lacquering of the deposit and of the destruction of cyanides, gold plating may be the best treatment- for which you may also ask a better payment.

Best regards,

Emmanuel Popesco
- France


October 2, 2012

A. I wouldn't recommend trying to change a stable bath to satisfy one customer. You will be fighting a losing battle with all other comers. It wasn't mentioned whether you lacquer the parts or not and if they are baked after lacquer. I have turned bright brass a gold color by baking them at 285 °F for approximately 20 minutes. This will work with a "flash" deposit. If you must change your chemistry, I would recommend a 4:1 ratio of Zinc metal to copper and a 4:1 ratio of Zinc metal to free cyanide and run it at a slightly lower current density to draw out more copper. Hope this helps.

Bruce Wheeler, Finishing Engineer
- Berlin, Connecticut USA


August 3, 2018

A. Plate a matte nickel or dull nickel plating on the brass panel, reduce the nickel content in the gold bath it will match the original gold colour.

narayana swamy reddy
- bangalore karnataka, india


June 21, 2019

A. Yes I also tried lemon yellow is the usual colour suitable for production if try to change the colour by changing composition of metal and temperature result one batch came in golden colour but next batch will change. Better idea is apply an MRF clear coat, it slightly yellow tone so light golden yellow is added if you don't want yellow wanted transparent clear use ESDEE clear.

vasanth kumar
Gold plating art studio LLP - chennai,Tamil nadu,india



Turn iron into gold color

October 27, 2020

Q. Hi,
I want information about electroplating for stainless steel or iron to change the color to bright gold.

I tried many ways, the last one was electroplating iron with brass but the result was not golden color.

Thank you.

Awder Hussein
- Sulaymaniyah KRI Iraq


October 2020

A. Hi Awder. Unfortunately you can't simply say "I tried to electroplate and it didn't work; how do I get bright gold color on iron & stainless steel?". There's a lot to it: I have 100+ plating books, and my bookshelves are quite small compared to many :-)

Instead, please tell us with full details what you are trying to plate, and what steps you tried, and what happened. Did you buff the iron to a good finish first? Did you meticulously clean it to a waterbreak-free degree? Did you acid activate it? Did you nickel plate it before the brass plating? Was the nickel plating successful?

On thread 28032 you asked for a brass plating formula and we reprinted 6 of them from Lowenheim's "Electroplating" and "Modern Electroplating" ... is one of those what you tried, and it worked but the color wasn't close enough? If so, send photos making sure some recognizable things are in the picture to calibrate our eyes. I appreciate your frustration with being unable to find supplies, but unfortunately electroplating is complicated enough that you won't get a 2-paragraph public forum explanation of what to do; you'll have to go a step at a time :-)

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading


October 27, 2020

Q. Thank you dear for your reply,

Actually I tried below ways;

* Tried to make acid copper by mixing Soda and water with two plates of brass (Cathode and anode). The solution turned blue but when I used it for plating the iron it turned rose gold after grinding.

* I tried to mix the powder which is used to cover silver to gold (Sorry I don't know the chemical name but it was like salt, white and hard). The result became very light gold.

How can I turn it to bright bold gold not light?

FYKI: I tried many many ways, I'm searching for over two months but still stuck, also I don't believe that I can get what I want in two paragraphs.

Thank you for your reply.

Awder Hussein [returning]
- Sulaymaniyah KRI Iraq


October 2020

A. Hi again cousin Awder. I wish I knew a way to do what you want, but I don't. All I can do is put your posting on this page, which gets a lot of readers, and see if anyone has advice for you.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading


October 28, 2020

thumbs up sign Thank you so much dear sir,

Even I tried to get a consultant but none of them are responding.

Awder Hussein [returning]
- Sulaymaniyah KRI Iraq


November 19, 2020

A. There are many ways of creating a gold colour on iron, but the first stage is to make sure your iron substrate surface is suitable -- it needs to be very smooth and clean. The flatter/smoother it is (i.e., polished) the better the surface coating will appear.
A common way of creating a gold looking surface is to deposit tungsten carbide (WC) this is done by PVD. WC is hard, so it is also used in conjunction with a gold flash to provide a hard wearing gold coloured surface.
Secondly, you can use a brass alloy deposit -- the ratio of Cu:Zn will affect the colour, so try a range of compositions and see which one is best for you. Thirdly, you can always plate the iron with gold - but that is expensive!

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


November 27, 2020

Q. Thank you sir for your reply,

Does it means the more Zn in solution makes more yellowish color like red yellow "Gold"?
I'm using same but I get pale yellow coating? Should I add more Zn?

Regards,

Awder Hussein [returning]
- Sulaymaniyah KRI Iraq


November 2020

A. Hi Awder. The more zinc in the deposit, the more yellow it will be; the more copper in the deposit, the more red it will be. But this still leaves two problems:
1. Brass does not look quite like gold, and it's probably not just a matter of how much orange tone is in it.
2. Copper is so much more noble than zinc that the way you must get zinc into the deposit is by complexing the copper, so adjusting the copper to zinc ratio in a deposit of brass involves a lot more than just the ratio of metal contents in solution. I don't think you'll get there with solutions based on "soda and water".

If you are doing individual pieces of art rather than attempting any sort of production plating, however, what might work is doing copper plating first, then zinc plating, and heating over a gas burner to cause diffusion. In this case I think (but I do not know) that by adjusting the thickness of the zinc plating layer and/or the heating time you may be able to adjust the color. There is a trick you can look up on the internet of zinc plating a copper coin, then heating it to get a gold color, and googling that subject may offer some clues. Good luck!

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading


November 27, 2020

thumbs up sign Thank you Mr. Mooney,
I was about to change my route of thinking that way. Will try this one and will get back to you about the result for sure.

Regards,

Awder Hussein [returning]
- Sulaymaniyah KRI Iraq

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