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topic 59642

Unsatisfied with jewelry plating services, is quality plating possible?


June 12, 2014

Q. Hello,

I am extremely frustrated with the whole plating process.
I produce small volumes so I have access to only small plating shops who don't really know what they're doing, and won't change their processes to suit my needs. All I can get is 0.2 to 0.4 micron whereas I would want 2.5 or 3 microns, plus a nano-ceramic coating or other protective coating.

I think that I am left with 2 choices: stop plating entirely, or setup a plating bench specifically for my items (and hire someone to run it). Do you think that it is an unreasonable idea?

I have some questions:

1. If it is essential to maintain the gold content of a bath for consistent results, how do you accurately measure that gold content?
2. Is it possible to calculate how much it would cost in gold/solution (excluding labor I mean) to plate 3 microns on a 1" round pendant, and a thin 18" chain?
3. I've been told that nano-ceramic coating wasn't suitable for thin chain because it is too thick: is that true?
4. Will a nano-ceramic coat really protect the plating and make it last longer?
5. I read an old post here from a person in India who said that they plated watches with 6 microns of nickel, then 3 microns of gold.
Any idea how long such a plating would hold on a watch worn daily? Also, if the watch was I imagine in stainless steel, why is it necessary to have such a thick nickel undercoat?

I thank you in advance for your help
Seb

Seb Guy
designer - Seoul South Korea
  ^- Privately contact this inquirer -^


June 2014

A. Hi Seb. I don't know the situation in South Korea or the other countries where you've sought plating services, but I am surprised that no one will do what you want. I'd rather not offer an opinion on whether you should go into the plating business yourself because I don't know you or your needs well enough; for that question I think you should retain a plating consultant.

Gold Plating Technology


For the question regarding plating thickness vs. life, I am not a jewelry expert, just an avid reader of the quarter-million postings that people have sent us, but this is my impression: The top end of gold plating thickness these days seems to be 20 microns, used on the world's finest watches -- heirlooms expected to last many decades. Much jewelry is done in "micron gold", i.e., 1 micron thickness, which is good costume jewelry such as would be used on nice-quality gold plated sterling silver earrings. 3 microns thus sounds to be quite high quality plating, suitable for a "good" watch (a several hundred dollar watch, but not a twenty thousand dollar watch), or the very best non-precious metal jewelry a department store has to offer. The lifetime of any particular thickness is very hard to estimate, but is proportional to thickness, and 3 microns should be very satisfactory for any jewelry.

It should not require great skill to apply 3 microns of a standard yellow gold as I am not aware of any technical hurdles at that thickness -- it's just a matter of plating for 3x longer time than for 1 micron.

1. It is possible to maintain the gold content, check for impurities, etc., a number of different ways depending on your budget: gravimetric, volumetric, colorimetric, polarigraphic, spectrophotometric, and atomic absorption. Goldie =>
has a 25-page chapter introducing these methods with a bibliography of 76 references. But when you buy your gold plating solution from specialty suppliers like DeGussa or Technic; they provide technical data sheets about how to maintain the solution, and they offer laboratory services for things that are too difficult for you to measure in-house.

2. The volume of gold you will use is simply the average thickness times the surface area plated ... but it is acknowledged that it's not always easy to accurately estimate surface area.

3. "Nano-ceramic" is more a buzzword than a technical specification. It implies that the ceramic particles/crystals in the solution are much smaller than would be obtained by conventional manufacturing, and that new properties have emerged because of this greatly increased ratio of surface to volume, or other factors that come into play at nanoscale. I found the following video to be one of the most interesting on the subject:

But some manufacturers of clear "nano ceramic" topcoats claim that the thickness of their coatings is 1/2 to 2 microns. It doesn't sound like a problem to me.

4. Any clear coat on top of the gold plating will increase its life, and electrocoatings or UV coatings are additional alternatives to the nano-ceramics. In your position, I would go to Degussa, Technic, or another first line supplier of gold plating processes and get their input on recommended topcoats. They probably offer a "system", a specific topcoat on top of a specific gold layer.

Regards,

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


June 16, 2014

A. We're a high-end faucet manufacturer. Most of the faucet industry gave up on gold plating years ago and opted for PVD gold. The coating is not gold, but a hard ceramic nitride that wears much, much better than gold. It is largely the same coating used on metal cutting tools. You shouldn't have a problem finding a PVD vendor in South Korea.

jim treglio portrait
Jim Treglio
- Vista, California


June 2014

Thanks Jim, you're certainly right! But the issue then becomes this: if the cheapest costume jewelry uses a PVD coating instead of gold, and Seb uses that same technology, and gets the same not quite gold color, and the same life, what would distinguish his supposedly high quality jewelry from the cheapest? If it looks like a duck, walks like a duck, and quacks like a duck ...

Sometimes you have to use gold if for no other reason than to use gold :-)

Regards,

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


June 17, 2014

thumbs up signYes I've considered PVD, thanks a lot for bringing that up.

From what I understand, all high end watchmakers use that for their wrist bands and cases.
Ted, I think that people who want high end jewelry buy solid gold. In my experience, most people who buy plated jewelry are concerned about the color and the durability, so if I could have access to PVD, I'd probably go for it.

The problem with PVD is that it requires large volumes. No provider will take my small volumes.
Therefore my only solution is to set up a plating bench to make high end plating, because I suppose that PVD equipment cost 100s of thousands of $, and is probably very difficult to operate.

I'm going to contact Degussa (or Uyemura, I'm confused) and Technic here to see what they say.

Thanks

seb Guy [returning]
- Seoul South Korea



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