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topic 49751

White Bronze Plating: an alternative to nickel


A discussion started in 2003 but continuing through 2020

2003

Q. Does anybody know about the corrosion resistance (in terms of ASTM ASTM B117 [link by ed. to spec at TechStreet] , hours) of white bronze (with and without zinc/lead) coatings?

Best regards,

Emrah Inçal
- Istanbul, Turkey



August 22, 2008

Q. I'm looking for a more environmentally friendly alternative to nickel plating on brass. Would cyanide-free white bronze plating be a good candidate?
Any other suggestions would also be appreciated.

Thanks,

Liz Dean
Intern, Production Eng - Birmingham, UK
outdated


August 22, 2008

A. Hi, Liz. Yes, white bronze is a substitute for nickel and will often will prove acceptable. And if your product is jewelry, it addresses the issue of nickel allergy (nickel is not permitted on jewelry in the EU).

But "environmentally friendly" can be just an empty buzzword without agreed-upon metrics. It's often hard to know if a change is doing the earth a favor or a disservice :-)

For example, due to constant environmental pressure to reduce phosphatizing, the world suffers multibillion dollar annual corrosion, a colossal waste of resources, and complete lack of sustainability because so much steel is NOT phosphated. This dwarfs "the phosphatizing problem" as we mine, smelt, roll, fabricate, paint, package, sell, ship, scrap, and replace tons of steel every 3 years instead of every 15 years -- but we saved a pound of phosphate per ton of steel. Please try to tell us what comprises "environmentally friendly" in your mind and then we can try to answer. Good luck.

Regards,

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


September 5, 2008

A. Liz, you are in the heart of the jewellery trade in the UK. There are numerous organisations within 10 minutes walk of the city centre that can answer your problems and give you a huge insight into the metal finishing industry. Try talking with the Institute of Metal Finishing on Holloway Head, or the Metal Finishers Association in Vyse Street. There is also the Jewellery Manufacturers Association (I think in Vyse Street) and there is the College of Jewellery and Design (University of Central England, NOT Birmingham or Aston!)
White bronze is being used as a barrier layer in jewellery and other parts where nickel is banned. It does work well and is very effective. However, there are other alternatives, depending on what you are trying to do. If you can tell us what you are doing, there will be more help, but tap into the knowledge of your local experts first! Sorry to be so negative, but do the groundwork first and then come back and see what we can offer.

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


September 9, 2008

Q. Hi,

Currently, we are plating brass fittings with bright nickel for identification between imperial and metric size parts (metric are plated, imperial left brass-coloured), aesthetics and corrosion resistance. But, looking ahead to REACH regulations from the EU, substances, such as nickel, are being restricted. This is why I'm looking for processes that will not be condemned by the EU in a few years time. I've looked at metal plating, such as white bronze, zinc, tin-cobalt, as well as dry deposition techniques, such as PVD, CVD, HVOF. What I'm looking for is something that is ideal for barrel plating large volumes of small fittings with a decorative commercial finish, typically 3-5 microns thick, but preferably does not contain nickel or compounds equally or more toxic.

Thanks,

Liz Dean [returning]
- Birmingham, UK


September , 2008

A. White bronze should be a good choice because it looks like what you are currently using, Liz; and it is widely used in jewelry, so there will be ready commercial sources.

Many people have skin allergies to nickel, but I certainly would not call it "toxic". Electroformed nickel is used in stints and other items implanted into the body, for example. Hopefully if you or I ever need a stint it will be electroformed nickel rather than white bronze :-)

Regards,

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


September 15, 2008

A. Liz, I am only trying to second guess what you really want - barrel plating is relatively easy to do, but you are limited to metals and alloys that can be electrodeposited from aqueous solutions. However, there is technology around that uses a barrel plating concept but with PVD/CVD type equipment. The people doing it in the UK are Teer Coatings Ltd in Droitwich - well worth a quick 'phone call and chat! Have a look at their website.

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



White Bronze Corrosion Resistance per ASTM B117
(Techni-White, Albaloy, Miralloy, Optalloy, copper/tin/zinc alloy plating)

October 15, 2008

Hi,

We are plating brass parts with 200-250 micro inches of Albaloy and the plating hasn't been withstanding an intense Salt Fog test per ASTM B117 [link by ed. to spec at TechStreet] . Should Albaloy plating hold up to a 40 day salt fog test? What thickness would be required to prevent any staining on the connector? Are there any alternate suggestions on plating that can withstand such a test?

Thanks and best regards,

Rob

Robert Di Carlo
Project Engineer - Beverly, Massachusetts


October 21, 2008

A. Hello Robert,

The corrosion resistance of White Bronze will depend on the base metal condition( Ra values) & the porosity of the brass in addition to the porosity of the Plating.

You can increase the corrosion resistance by plating two layers of White Bronze in different Chemistries, or adding a topcoat of Tin-Nickel alloy over the White bronze a topcoat.

Khozem Vahaanwala
Khozem Vahaanwala
Saify Ind supporting advertiser
Bangalore, Karnataka, India

saify logo


October 27, 2008

Q. Thank you Khozem. My customer is recommending that we use a Silver underplate. Does that make sense to you?

Thanks again,
Rob

Robert Di Carlo
- Beverly, Massachusetts


December 4, 2008

A. Hi again,

Sorry for the late response, I don't think its necessary, I recommend a minimum 3 micron coat of bright acid copper plating directly over the brass before any other plating instead.

Khozem Vahaanwala
Khozem Vahaanwala
Saify Ind supporting advertiser
Bangalore, Karnataka, India

saify logo



December 13, 2012

Q. Hello all.

Firstly thank you all very much for your time and effort in creating a very helpful site, I started a very basic Jewellery finishing business in Egypt 3 years ago and this site was of paramount help; even if it didn't always dish the facts on a plate, it helped me to learn what I needed to know.

At this stage of the business we wish to send goods to Europe and the USA; many goods produced here would benefit from a nickel-style undercoat before being flash/pen plated in Silver, Rhodium or Gold..

Nickel is still the primary agent used despite many people suffering allergies here too. I would like to introduce white bronze plating to Cairo. I have a basic workshop with a working budget (not a huge a one) but I have access to 10-100 amp transformers used for plating, most chemicals and common equipment. We construct the baths here, my workshop has ample ventilation and is safer than most, I take care of myself, my staff and my customers.

Any assistance into the technical requirements for a small scale white bronze plating bath solution and anode requirements would be extremely helpful, I am of course aware different people have different opinions and I will take what good I can find in them with gratitude.

Please note any further references or other insightful resources would also be well received; while I do not wish to seem too frugal, the truth is I work within a very tight frame of economics and prefer the small start up that grows as opposed to the large capital hungry business model.

kind regards

Lee Amin
- Cairo, Egypt

----
Ed. note: Hi Lee. We have a half-dozen or dozen threads about various aspects of white bronze plating. Please put " 'white bronze' " into the custom search engine and look around a bit. Good luck.




White Bronze Plating of Zinc Die Cast Jewelry: Thickness Needed?

September 16, 2015

Q. Hello all,

I'm a young engineer working on a wearable technology product. I'm new to the world of electroplated finishes, and would appreciate some advice.

I have a zinc die cast component that sits in constant contact with the skin, like the back of a watch. The surface of the raw die cast zinc components quickly darkens in contact with the skin. I would like to electroplate a layer of white bronze to prevent this from happening, while preserving the electrical conductivity of the part (necessary for the application). I would have chosen chrome, were it not for concerns over nickel allergies.

Can I ask for some suggestions as to thickness? I have gotten a quote for a 2.5 micron layer for a price that I consider quite reasonable, but I'm wondering if that will be sufficient. My goal is for the coating to survive a year in constant contact with the human skin.

I've learned a ton from reading these forums, and would be grateful for any insight you folks could provide!

Regards,
Roger

Roger Yronwood
Engineer - Cambridge, Massachusetts


October 10, 2015

A. Hello,
2.5 microns will be fine. I'm sure your plater will know what chemistry they will use that will coat and seal the surface of the Zn die-cast parts before the white bronze plating.

Mark Baker
Process Engineer - Phoenix, Arizona USA



December 22, 2019

Q. We are doing white bronze plating. We see some white precipitation in the bath, which we guess may be tin.
Bath temperature is 60 °C and pH is 11.5

I have the following questions:
- when does tin deposit in white bronze bath?
- how can it be redissolved?

Any suggestion will be highly appreciated.

niloofar niknam
- shiraz, iran


January 3, 2020

A. Hello niloofar

I hate to be the one to tell you, but typically once the tin drops out of solution in alloy plating, the bath is most likely considered dead. The tin drops out of solution because it oxidizes. Once oxidized the solution is [un]able to redissolve it easily without destroying other components within the bath.

The most common reason tin drops out of solution is through aeration. This is usually through the use of air agitation in the solution (don't use air; use eductors for solution mix) or the pump is pulling in air and mixing it with solution.

There are a wide range of other reasons for tin to drop out however that is dependent on the chemistry of bath you are running.

Hope this helps!

William Hogan
Amphenol Aerospace - Sidney, New York USA

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