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topic 1114

Bronze plating solution and parameters




An ongoing discussion from 1997 through 2015 . . .

(1997)

Q. I want to make a bronze plating solution and the preplate needed. The bronze must have hardness more than 40 Rc.

Please give me the chemicals percentage to make the solution that you recommend.

Thank you.

Remberto Brito
S.A. de C.V.


(1997)

A. Remberto,

Macdermid Inc. [a finishing.com supporting advertiser] has a bronze solution that we use for antique gold and nickel-free plating for jewellery. I do not know the hardness but you could try Macdermid.

Regards

bob lynch
Bob Lynch
     plating company
Sydney, Australia



(1997)

A. Mr. Brito

We also use some Macdermid Inc. [a finishing.com supporting advertiser] chemicals to make up a Bronze plating bath. We use oxygen free copper anodes, potassium stannate, potassium hydroxide, potassium cyanide, and Rocheltex.

Concentrations are as follows:

Copper 5 oz/gal
Stannate 1.5 oz/gal
Hydroxide 0.7 oz/gal
Cyanide 5 oz/gal

Sincerely

Wes Yancey
General Electric


(1998)

Q. Dear reader,

I would like to produce a bronze patina/finish on a set of plain metal door hinges so that these fittings will blend with the overall appearance of the door. I was informed that a simple method involved soaking the metal hinges in a solution of ammonia. Is there any truth in this recommendation. If not can you suggest a method which is not too involved and does not rely on the use of chemicals which release harmful gases. Thank you for your help in this matter.

Joseph Hayek



A. Hi Joseph. When you say "plain metal" I guess you are suggesting that they are made of steel? Ammonia is sometimes used to color brass, but I don't think it can turn steel to a brass color. The hinges can be brass plated but it sounds like that's probably not something you wish to do yourself, and it certainly involves hazardous chemicals -- so you would need to send them to a plating shop. Alternately there are brass-tone paints, brass-tone wax rubs (probably good for an interior door, not so good for an exterior one), and patinas that may be brass colored.

Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



Bronze plating process parameters

(2003)

Q. I need to know what amperage to use for bronze plating in an existing cyanide bath. less than 1 sq. ft substrate area thanks!

John Wanninger
silversmiths - Placerville, California


(2003)

A. Cathodic current density between 20 and 50 ASF; anodic current density less than 20 ASF.
(Assuming it is a cyanide bath!)

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



(2004)

Q. We are trying to duplicate a plating process on a part thru reverse engineering. The completed part has a phosphor-bronze plating (~90 copper/~10 tin) composition. The finish plating thickness is .030-.040" thick. The part base material is a ductile iron, with a nickel strike between the iron and the plating.

I am not able to find any SAE/AMS/ASTM specification covering bronze plating.

There is a specification on how to plate this material, but it is proprietary. How can I duplicate this process or write my own specification to duplicate this process? How can I insure the material is properly bonded to the base material?

Please help,

Mark Powell
aircraft parts - Atlanta, Georgia, USA


(2004)

A. I would define plating as a process to deposit a metal or alloy onto a surface by means of a liquid that contains metallic ions. Now, how do you know the part was plated if you didn't do it? Could it be processed by a different method? I can think of at least five different processes that can produce a rather thick layer like that.

1- conventional thermospray (porous fair bond)
2- plasma spray (less porous better bond)
3- HVOF (almost zero pores good bond)
4- spark deposition (zero pores weld bond)
5- high energy cladding (same).

All have advantages and disadvantages over plating of course, but are not proprietary.

G. Marrufo-Mexico

PS. Frequent readers are welcome to remind me or correct me.

Guillermo Marrufo
Monterrey, NL, Mexico



To minimize searching and offer multiple viewpoints, we've combined multiple threads into the dialog you're viewing. Please forgive any resultant repetition or failures of chronological order.



Need reliable Bronze plating bath

(2005)

RFQ: I work for a small plating shop that wants to begin bronze plating for decorative purposes. We have used the guidebook's formulation in the past and found it difficult to control and a short life. I have begun researching vendors of bronze plating baths that will have stabilizers and other additives to help with the control and life but find that either they have discontinued bronze and brass baths or the vendor is located in India.

I have nothing against India but I would like to find a vendor in the US.

Can anyone direct me to a vendor that has a reliable bronze bath.

Tim H [last name deleted for privacy by Editor]
Decorative Plating - Miami, Florida, USA
^- Sorry, this RFQ is outdated
     View Current RFQs



(2007)

A. If the Cu-Sn plating contains phosphorus, it was most likely deposited using an alkaline pyrophosphate solution (in order to avoid the use of cyanide in the plating bath). No ASM specification currently exists to govern alkaline Cu-Sn electroplating. However, AMS2429 [link by ed. to spec at TechStreet] governs plating production of 90Cu-10Sn nitriding stop-off in a cyanide acid bath. The cyanide acid bath is a much more efficient and time-friendly process, and will typically provide a much more uniform plating layer than the alkaline bath; however, due to environmental and health considerations with the cyanide bath, more shops are considering use of the pyrophosphate alkaline baths.

Richard A. Schreiman, M&P Engineer
aerospace - Irvine, California, USA

----
Ed. note: Readers may also find letter 24316, "Bronze Plating Processes, Procedures, and Problems" helpful.




Need reliable Bronze plating bath

(2005) -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

I work for a small plating shop that wants to begin bronze plating for decorative purposes. We have used the guidebook's formulation in the past and found it difficult to control and a short life. I have begun researching vendors of bronze plating baths that will have stabilizers and other additives to help with the control and life but find that either they have discontinued bronze and brass baths or the vendor is located in India.

I have nothing against India but I would like to find a vendor in the US.

Can anyone direct me to a vendor that has a reliable bronze bath.

Tim Hamlett
Decorative Plating - Miami, Florida, USA



Best anode material for a Bronze plating bath

June 12, 2015

Q. I am looking to make improvements in my racking system for production parts and I'm getting conflicting information. I'm just looking for another opinion.

My rack supplier is recommending titanium rod for small diameter anodes (to prevent the anode from degrading prematurely). These smaller rod anodes (0.200" - 0.375" in diam) degrade quickly and short out because of uneven wear, causing problems with my production parts. I am looking to find a way to extend the diameter / life of the anode and get more consistency with my smaller diameter parts.

I have a plating consultant who is disputing this recommendation stating that the titanium will 'contaminate' the bath and is recommending a 400 series grade tool steel. I'm unsure how this will contaminate the bath worse than the soft steel anodes we currently use.

Is the rack supplier just trying to get more money or is the plating consultant off on this one?

What are your thoughts?

Thanks,
Dawn

Dawn Baeckeroot
Process Engineer - Alden


June 2015

A. Hi Dawn. I'm not fully understanding your description. I guess your plating racks (the fixtures that your parts are mounted on) are equipped with "auxiliary anodes" -- electrodes which are not designed to dissolve into the solution like consumable anodes, but simply to selectively deliver electricity to specific areas of your parts (like deep recesses)?

The "right" or "best" material for auxiliary anodes is usually platinum clad titanium, as it will have a very long life, but it is very expensive. For a bronze plating bath you want your consumable anodes of tin and copper to dissolve into the solution, but you'd like your auxiliary anodes to last forever.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


June 14, 2015

A. If mild steel is causing problems, I would personally try something else.
Hard copper comes to mind as being a bit less contaminating than iron. If it dissolves too fast it will throw off your copper - tin ratio.

I am not aware of any 400 series tool steel. There is 400 series stainless steel which is used for knives and etc.
"tool Steel" would normally be a 4xxx series.

400 series nickel rod might be a decent alternative. No chrome and no steel. I think that it would dissolve slower, but I am NOT positive about that. I have used it for an aux anode in selective nickel planting.

James Watts
- Navarre, Florida


simultaneous June 15, 2015

thumbs up sign Hi, yes, our situation has auxiliary anodes and yes, we would like as little degradation and as long a life as possible out of them.

And yes, I know that it's going to be expensive. That's the question is how expensive and will it offset our scrap we get from our very small anodes being eroded away, shorting out and causing quality issues with our parts.

Thanks! That's exactly the info I was looking for! I appreciate the feedback!

Dawn

Dawn Baeckeroot
- Bellaire, Michigan USA


June 15, 2015

A. If the bronze plating solution is alkaline, then the titanium will anodize and stop passing current (just like titanium anode baskets in a cyanide solution).

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina

Editor's note: Mr. Probert is the author of Aluminum How-To / Aluminio El Como


October 22, 2015

A. The anodes for alkaline bronze plating is MMO = mixed metal oxide.

Sara Michaeli
Sara Michaeli signature 
Sara Michaeli
chemical process supplier
Tel-Aviv, Israel




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