The authoritative public forum
  for Metal Finishing since 1989
-----

White final finish for fashion jewelry

Hi, I am a fashion jewelry manufacturer. The jewelry is a medium type, not very cheap and not that expensive. We have suffered in getting an appealing white final finish. I have considered using white bronze but it seems to be very difficult process. I have used a palladium process from one of the recognized international suppliers. The whiteness of palladium is good but we need a whiter finish as supplied by far east jewelry manufac. I had sent some Chinese jewelry samples to the Umicore lab and they replied that some of the samples were final plated with white bronze and some with palladium. However when I did palladium on my jewelry it never turned out to be that white. Can some guide me what should be the best way to achieve the white plating?

Ahmed Jamsa
traders - Karachi, Pakistan
April 6, 2009

I have found in the past that decorative palladium is not as white as rhodium. White bronze however can be as white if the process is watched closely. You can ask around in your industry to see what white bronze bath mfgrs are using, and ask what the level of tech support is like from the supplier or distributor. With the price of rhodium being what it is, it would probably cut into your profits. Good Luck!

Mark Baker
Fellow Plater - Syracuse, NY, USA
April 8, 2009

Hi, unfortunately we don't have any suppliers or companies selling a white bronze electrolyte. So the running of the bath and maintaining the bath is out of question. Please advice further.

Ahmed Jamsa
- Karachi, Pakistan
April 9, 2009

If palladium isn't white enough, and white bronze is out of the question, a thin coating of rhodium would be my only suggestion at this point. Is it not a good practice for anyone on this website to make a suggestion regarding additions to a proprietary palladium bath to make the deposit whiter. Your palladium bath supplier should do that.

Mark Baker
Fellow Plater - Syracuse, NY, USA
April 20, 2009

---

Hi Ahmed,
As Mark baker said it is entirely possible to get a Rhodium like finish in white bronze bath provided you run it with proper maintenance.The process being an alloy plating with Copper,Tin and Zinc, the main area you should watch is temperature and current density.Run the bath @ 0.5 to 1 amp/ dm2 and @ 55C..Pot.cyanide conc. is also important(50-60 g/l).lesser volume say less than 100 ltrs also gives undesirable result.Have a flash of Rhodium over it.If costing allows,a flash of palladium and then flash of Rhodium will be an excellent idea.Look around. you will get some good suppliers of this process.
Good luck

T.K. Mohan
plating process supplier - Mumbai, India
April 28, 2009

---

Hi Mohan,

Well as you know rhodium is never a consideration as the cost is very volatile. White bronze has a very good colour but the maintenance is a difficult job. Is there an easy way of maintaining the white bronze process, can we analyse the electrolyte by titrations or is AAS a must (AAS is not very easily available you know). What happens if the bath of white bronze is less than 100L. Is tin-cobalt an option for us? Last but not the least Which white bronze do you recommend I mean from which company?

Ahmed Jamsa
- Karachi, Pakistan
May 3, 2009

---

May 8, 2009

Dear Ahmed
As I mentioned earlier this being an alloy plating and as the composition of the bath is having less gram/ltrs metals as constituents, you will have to handle it with care.But it is not difficult.I understand, to get a rhodium like finish, the deposit should have approx. 65:35:5 ratio of Copper,Tin & Zinc.So you need to replenish the bath periodically say hourly.
1.Bath volume can be 50 ltrs also if you are ready to replenish the bath as mentioned above.
2.Temperature controller-Thermostat required
3.Ampere minute meter required.
4.High quality KOH required
5.De-mineralised water required
6.Constituents have to be analysed by AAS.If you do not have, get the help from professional lab
A.Please preserve samples of the bath say every 4 hours continues production. 4 samples.
B.Get it analysed from professional lab including Cyanide
C.Note the ampere minutes passed.
Now you can relate the addition of constituents and derive the additions required for every hour.
There are a couple of suppliers of these processes worldwide (this forum does not allow me to give names as this will attract Ted's warning to me!)

T.K. Mohan
plating process supplier - Mumbai, India

Ed. note: Exactly, T.K. :-)    Supporting advertisers cheerfully pay the costs of this forum so we can all share camaraderie with our peers around the world and exchange technical tips. But for us to spend their money promoting their competition's interests would certainly be abusing their generosity. "Suppliers of these processes worldwide" are of course welcome to be supporting advertisers themselves, in which case advertisements for those products complete with their contact info would be directly on this page :-) Ted

adv.:    Discover the choice made by manufacturers
nationwide for high quality jewelry plating & finishing