Imitation rhodium plating chemistry

A. IT IS ALSO [called] TRI METALLIC ALLOY PLATING.

A. There was a full page ad in the January 2001 Metal Finishing mag for a product called Miralloy (Cu/Sn/Zn alloy) by Degussa Galvanotechnik (maybe your 'Tagusha' is Degussa?) giving the North American distributor as Uyemura International Corp.

Regards

A. Hello Gusti,

It's white Nickel plating; Bright Nickel made to look whiter just like white bronze. Please pass on a hello to Mr Jal.

Regards,

A. It is probably bright tin.

A. Hallo Gusti,

I'm doing Imitation Rhodium or imitation chrome with white free solution which is tin & cobalt, over bright nickel it looks good, shines, but does not last like real rhodium.

This solution I get from Gold Touch [a finishing.com supporting advertiser]

A. In China, some add cobalt to bright nickel plating bath to get Whiter finishing. This method is very low cost but easy tarnished.

A. Hi Gusti. Four experienced posters have told us that they are familiar with the use of --
• White nickel, a whiter nickel, possibly brightened with some cobalt,
• Bright tin plating, possibly with lacquer,
• Tin-cobalt plating over nickel plating
-- as substitutes for rhodium. So if you're sure it's not white bronze, and the economics preclude it being real rhodium, it may be one of those three. Good luck.

Luck & Regards,

A. Hi Gusti,

You were right White Bronze with lacquer is used as Imitation Rhodium, Some others use Tin and lacquer.
With Regards,

A. Dear Ahmed,
White Bronze was introduced to possibly replace costly Palladium to have a barrier layer usually over copper and brass in Nickel free jewelry plating.By virtue of its bright white look resembling to Rhodium,Imitation Jewelry manufactures from mainly India, China, Hong Kong, Taiwan and now in Pakistan have opted to plate White Bronze to make cheaper jewelry. The finish and look can sometimes pass as original Rhodium and named it as duplicate Rhodium.
This is an alloy plating of Copper/tin/Zinc and the deposit have high wear resistance (500V).Platers use an anti tarnish dip to make sure it does not lose its glow though it is not a must.
Meanwhile the process has to be operated strictly as per the suppliers recommendations to get the desired result.
Regards

A. Hi Warren. You may wish to listen to our podcast "The Lost Art of Tin-Nickel Plating"

Luck & Regards,

A. Hi Azhar,

White/yellow bronze plating is one of the most difficult platings and unless you maintain the bath with real care, you will end up getting results the way you said. Basically it is a 3 metal alloy plating; copper, tin, zinc and with other metals (in ppm) in proprietary formulations.

Best way is to follow the supplier manual to the dot.
1. Install a rectifier with amp/minute meter
2. Replenish additives at small intervals say 1000 amp/min.
3. Maintain cyanide conc. (Add 10 gm/ltr and see the change!)
I can help you if you come out with more details such as how you maintain the bath as of now.
Regards,

A. Azhar,
White bronze plating is done as you know with inert anodes such as SS. So it is clear that the additive you use contains all the required ingredients to replenish the bath including metals. That is the reason I told you to make additions at small intervals. Cyanide additions have to be done in the same way. From the hull cell result I think CN is low. Start adding cyanide @50-60 grms after every 5 kgs plated.

HCD yellow is common in bronze plating. apply small current say 0.5-1.0 amps/Dm square (5-10 amp/sq/ft). Use continuous filter (solution movement is a must), have thermostat control temp to 50-60 degree.
I think you should be happy to receive suggestions whether I am a supplier or simply a person interested in helping friends like you!
Regards,

A. Hi there,

There are people using white bronze on 'throw out' basis (small baths), but if you want to use the bath for longer runs and especially for barrel plating then one needs to have the atomic absorption instrument ⇦ this on eBay or Amazon [affil links] to analyse the content, but if you have the job of same kind then amp/min/meter works, a good complexant with a very good proprietary brightening agent will help you solve all the problems.
Make additions at very short & regular intervals.

Hope this helps you.

Regards,

A. Dear all,

There are many possibilities to substitute for rhodium plating nowadays:

starting from the cheapest one:
- white bronze (CuZnSn)
- Platinium-Ruthenium 80/20
- Platinium Plating 100
- Platinium- Rhodium 50/50

To control those solutions it is recommended to have a proper Xray machine, a titration station, Hull Cell kit , and glass beaker [beakers on eBay or Amazon [affil links] setup.

Of course you also can run these electrolytes by experience, min. 3 years experience. It's always good if you have an external analytical lab around; from time to time it may is helpful to work with

Good wishes, Florian

A. Dear Hemal,

There are different Nickel Plating Brighteners for this application. It's as simple as buying different colors of paint. You can get Nickel to be as white as Silver plating if you like. Contact the supply houses in Mumbai for this.

A. Tri alloy does not tell some of us anything.
Salt spray is going to depend on the thickness, the quality of the zincate step and the quality of the plating step.

A. Dear Sir,

It's a common process and can be done. It will withstand the SST of 96 hours easily.

? For those of us that are not in India, what is tri-plate? If it is an alloy, what are the %'s?

A. Trialloy is a registered trademark for a tin / zinc / cobalt - alloy from UMICORE.

br
Franz

Thanks, Franz!

But your posting reinforces the validity of James Watts' complaint. Because the tin-zinc-cobalt alloy you are talking about is not the tin-zinc-copper 'white bronze' others have been talking about :-)

So how about it, Thirumurthy -- when you said "tri alloy", did you mean Umicore Trialloy® or did you mean white bronze alloys of copper, tin, and zinc ? Please flesh it out. Thanks.

Regards,