How to make gold plating last longer?

A. Hi Raj. Thanks for the kind preface, but it prompts me to add a preface as well ... There was a time long long ago when gold plating might be as much as 20 microns thick. It gradually got much thinner. When I was a young man 2-1/2 microns was considered high quality plating and 1 microns was the "cheap" plating you'd find on costume jewelry a high school boy might give to his steady. Then it became a half micron, and a quarter, and even a tenth of a micron ... to the point where some people today nervily call one tenth micron plating "high quality" :-)

The point being that no matter how thin the plating, people will naturally always want it both thinner and longer lasting. But there may be a point at which the gold plating is already so thin and the actual cost of the gold so low, that it's questionable whether money can be saved by reducing the gold plating thickness but adding the cost of additional more exotic topcoats.

I'm told that inexpensive, easy to apply 2-component automotive clearcoats are reasonably good.; I'm told that UV-cured topcoats (fingernail lacquer) are reasonably good and inexpensive to apply. Although I have seen electrocoating a few times; I have not personally seen an electrocoating line for jewelry, but imagine it to be rather expensive capital equipment.

The suppliers of electrophoretic lacquer can do samples for you and you can compare them to what you get from automotive clear coats or UV-cured clearcoats before committing to actually installing an e-coating line, but I suspect that focusing on proper undercoats like high quality white bronze plating, plus making sure your gold or silver is thick enough to be pore-free, followed by the simple clearcoats will be fine for low and medium volume. If you are into really high volume that justifies large capital expense, I suspect you will be happier with titanium nitride PVD hardcoating than with electrocoating ... but all I know is what I read -- I don't have hands-on experience with such comparisons.

Luck & Regards,

A. Thanks again for the kind words, Raj. I can't help you further but hopefully another reader will.

While I understand metal finishing and how to retard corrosion, tarnish, and other problems, I have no actual experience with jewelry manufacturers, distribution methods, industry practices, etc., so I don't know what options are available to you, so can't offer practical advice on how you can best fulfill your requirements :-(

Luck & Regards,

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A. Hello, Mat. Actually, I think it is a fairly well developed technology to combine titanium nitriding PVD processing and gold plating to provide a good gold color and a wear resistant surface. The thing is, it is rather inexpensive for a very small shop to do gold plating (especially if they don't have environmental regulators monitoring them), but a PVD vacuum chamber is major capital equipment. So you won't often find tiny operations offering titanium nitride assisted gold plating.

A. Ted is exactly right. The technology for using titanium nitride and gold is well tried and tested. The titanium nitride is put down first as a "rough" deposit and then gold electrodeposited into the valleys of the rough surface. This gives a very high amount of gold on the surface, but it is protected by the "peaks" of TiN, so it doesn't wear away too fast.

A. Gold is soft, so it wears fairly fast. 1 micron is about enough to give it color. It also depends on what it is plated on. Copper and zinc will migrate thru a coating that thin in a few weeks.
You get what you pay for sometimes. Cheap will be cheap in most countries.

Q. Thanks for your reply, I wonder where I can find a suitable manufacturer to do the PVD Titanium Nitrides combined with gold electroplating?

Best Regards,

Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)

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A. One micron of gold should give a reasonable life for costume jewelry. Most costume jewelry is plated with a 'flash' of gold which is much less than a micron. Check the thickness; are you getting what you paid for?
Tarnish of thin gold deposits is associated with porosity or diffusion of the base coat. It is usual to apply an intermediate layer. In industrial applications this is usually nickel but some people are sensitive and can develop a form of dermatitis (do they never take their jewelry off?). Palladium/nickel is commonly used. Your supplier should know this.

P.S. 1 micron of gold cannot be accurately measured by microsection. You will need XRF - talk to a local plating house.

A. As per the series of experiments conducted by our company, the durability of depositing gold over titanium nitride would be as much as that of 1 micron. Sometimes the life term of the product can be 6 months also. To obtain a durability of nearly 3 years, it is recommended to do electrophoretic lacquer.

A. Hi Rebecca. Ideally, the titanium nitride is, as Trevor tells us, a rough surface with mountain peaks that protect the gold in the valleys from wearing off. Cost comparisons are difficult because non precious materials like TiN and e-coating lacquer are inexpensive, so you're usually looking at capital costs vs. labor costs. The capital cost of gold plating can be very low; jewellers can do it in a beaker [beakers on eBay or Amazon [affil links] with a stirrer on a hotplate. E-coating systems might cost $100,000 for a small setup to $1 million for a large one, and PVD systems cost something like $1 million and more. I believe it is relatively easy to incorporate 'contaminants' into PVD deposits to give a darker look.

Hi Huan. The coloring of gold is an art more than a science, but Al Weisburg's "Gold Plating" chapter in the Metal Finishing Guidebook includes a "Table 1 "that will give you a start on formulations and operating conditions for different colors.

Regards,

A. Hi cousin Bhavin. It is possible to electroplate gold before TiN deposition by PVD. I think, but do not know for sure, that is is also possible to electroplate gold plating on top of a thin TiN layer. But it is probably more customary to apply the gold via PVD as you say you are doing.

Surely there is something wrong with your figures? 0.05 microns of gold cannot possibly be costly as it is incredibly thin. Light gauge aluminum foil is 320X thicker :-)

Regards,

A. Hello Jon,
The jewelry industry has their own jargon especially when it comes to electroplating. Micron plating is not a considered a flash plate in Au plating. A micron is about 40 microinches give or take. Flash plating is conventionally anywhere from 3 to 10 microinches. You would be lucky to get 10 from most decorative Au platers. If the Au plating thickness was 1 micron and was alloyed for some hardness your products would last a year and even more. If you can't find a plater to put down that much Au, coatings are available that will not change the appearance of the final finish. Obviously your price to have the items plated / coated will be more expensive. Good Luck.

A. Hi, Rohan; Hi, John.
I'm not a jeweler, but since no answers have come so far, I'll provide my understanding, albeit not definitive answers.

Gold has been valued throughout history for its beauty, one aspect of which is that it doesn't tarnish or corrode. For that reason, no lacquer or topcoat is required to keep it bright, as is needed for copper or silver and other non-precious metals. So it has been customary to not topcoat gold or gold plating. That doesn't mean you can't put a clear topcoat on it; but it does mean that it may not be as well received, so you decide whether you will or you won't as a business decision depending upon how you want your jewelry perceived.

If you do topcoat it, with an electrophoretic lacquer for example, the thickness of the gold doesn't matter from a wear standpoint because it is underneath the clearcoat. If you don't clearcoat it, the gold itself will wear and must be thick enough to resist that wear for what you consider an acceptable life. 1 micron is probably sufficient to offer sufficient life for moderately priced jewelry if it sees little wear and no body contact. A ring would receive tremendous wear and body contact, a pin or brooch virtually no wear or body contact, a charm would probably depend on the exact design of the bracelet. Until I learn better myself, I don't think I'd do 1 micron without a clearcoat though if I wanted it to last several years.

A. A trick used by some jewellers is to coat the articles with titanium nitride and then put down a thin coating of gold. The TiN is relatively rough, and the gold fills the cavities (or valleys) as well as the peaks. However, as the gold wears off the peaks, the TiN offers a hard and wear resistant point that protects the gold further down the valley.

A. Hello Robert,
Hard gold plating is a gold plating process whereas the plating solution contains gold salts (Potassium Gold Aurocyanide, conducting salts, buffer salts, and an alloy or brightener. Potassium citrate versions have been common for many years. The gold plating thickness is normally higher than standard "color gold flashes". Whatever the alloy is in conjunction with the gold metal concentration in the bath, determines the color and hardness of the plating deposit. pH and bath temperature play a role as well. Diffusion barrier coatings (between the substrate and the gold plating) vary. White bronze has become popular, palladium is also a good option, but more expensive. As you probably know, nickel had been the most widely used barrier plate in jewelry plating, but over the past 15 - 20 years usage of Nickel has been on a steep decline because of consumer allergies. There are reputable gold plating suppliers out there. This website can satisfy your search for a good supplier. Because jewelry is gold plated you have to expect the deposit to wear off over the years. The wear life will of course be dependent on the piece. Are you plating rings that will be worn daily, or necklaces that will be worn a few times a month. E-coating is an option to extend the wear life, but I am not familiar with possible drawbacks. Good Luck.

A. Hi Isabella. 14K gold is 10/24 non-gold, and the color depends on those other 10 parts. "Gold coloring" is both an art form and a trade secret for the fastidious: it's not easy to get consistent color, and quite difficult to specify it -- but you can study that topic in plating textbooks. "Gold Plating Technology" has quite a bit of info on gold coloring.

I didn't understand your engraving description and problem, sorry; but is it possible that the engraving was done after the plating here, and before the plating there? Also, your Chinese supplier is doing "ion plating" -- but that's a method, like "electroplating" is a method; it may be gold plating but it may not be. Are you sure you specified "gold plating" rather than just "gold color"? Micron plating is neither a method nor a material; it's a gold plating thickness of one micron. I don't think you are getting from China what you thought you were asking for; but if what you actually want is only the appearance, and you're happy with the appearance, that's probably okay.

This is a forum of international camaraderie, so we naturally try to not stand in judgement of anyone's outsourcing choices. Still, a problem is that we receive hacking attempts every hour of every day from China, and so many thousands of pieces of spam from China every week, that we often must block large swaths of IP addresses from China, and in so doing we may inadvertently block a helpful response from China. So you probably can't expect much help from China. And you really can't expect domestic and other platers to spend their time for free here helping you cut them out of the loop. That would be like going to a Chevy dealer and expecting the salesperson to patiently spend her time helping you choose between a Honda and a Toyota. That's probably why you've received no responses in a couple of months. But best of luck.

Regards,

A. It isn't necessary to know all the costs involved in the manufacturing of the jewelry you are seeking to buy in order to get the best possible price but you will need detailed designs and exact specifications that you can give to multiple manufacturers for quotes. Based on some of your questions I'm guessing you have little experience and you should hire a consultant to help you write up the specifications you will want to use. A word of caution: we regularly receive jewelry items through our customers that have been gold plated in China and do not meet the specifications.