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Rose / pink /red gold plating issues: color is off, tarnishes quickly

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Q. I have a question regarding the colors of gold plating. I got a sample from a customer of a bracelet that was gold brush plated. The color to me was very yellow, almost fluorescent it was so bright. I sent the bracelet to see if I could obtain a solution so I could plate that color. The supplier said it was red gold and had a copper additive. I have rose gold here which has copper. When it is plated, it looks like there is no gold in it, just red copper. We have a normal cobalt hardened and cyanide gold we use for brush plating that has a what I call a reddish cast to it that is fairly deep in color. The baths we are using are acid cyanide. Has anyone out there got experience with gold colors that could help me or perhaps point me to somewhere I can get help. The colors I see seem not to coincide with what the gold is called (red, rose, etc.)

GoldTouch


A. Gold coloring is a treasured art form that I don't pretend expertise or experience in, so I hope you can get an authoritative answer from someone. But in the meanwhile, Alfred Weisberg's handbook article on the subject, which can be found in old issues of the Metal Finishing Guidebook or the Products Finishing [link is to product info at Amazon] Directory, gives charts of the various colors and the percentage of copper and nickel, etc., used to obtain them. Best of luck.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey

How to Make Gold Plating
Solutions (DVD)


++++

A. Hi,

I think this problem is of more copper content in the bath than what is recommended. So please reduce copper content in your bath; meanwhile maybe there may be a cause: if pH is too high this problem arises. Check the pH of your bath and then if bath contains organic contamination, that also may be one of the problems.

VADLAMANi SREENIVAS
- Hyderabad, Andhra Pradesh, India


June 19, 2010appended

Q. Dear all experts.
I use acid gold 3N deposit of 25 ml of gold deposit in copper jewelry but in flash process every time the strike color changes. How can I manage process so that I have the same color every time?

Abhishek Agrawal
plating shop - Indore, Nadhya, Pradesh, India


----appended

Q. Hello,

We are a job shop specializing in precious and semi-precious plating. We have some problems in maintaining a constant gold color in the 10 Kt specification using an alkaline gold bath with gold concentration at 0.1 oz/gal.

Going ISO 9002 is pushing us to better control the color specification and we would like to know what would be the best solution to have a 100% consistency in color -- is it through the use of an acid gold or is there a better solution?

Thanking you in advance,

Martin

Martin Bissonnette
plating shop - Lachenaie, Canada


A. Hi, Abhishek; hi, Martin. I don't have a definitive answer for you, but we appended your inquiries to a thread that at least offers a few hints. Good luck.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey



++appended

Q. Need to know about colouring gold (pink, green, red, etc.) Would anyone mind answering this? Need information about the process of colouring gold.

Thank You,

Jayalakshmi. S.

++

A. Hi, Jayalakshmi. In general, gold is not colored after casting or after plating. Rather, coloring is done by alloying other metals into the casting or into the plating. You will find some general introductory info about this subject in the Metal Finishing Guidebook. But at this point you may find the subject to be within the domain of art rather than science, with exact formulas rather closely held.

But in general, copper gives a pink to reddish cast; silver or tin a greenish cast, and nickel a Hamilton to whitish cast. Good luck.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey



+++

Q. I have had a difficult time getting a dark pink color out of the Red gold plating solutions we have tried. I have seen this color on some antique English pieces of jewelry but cannot seem to come up with it using materials available today. Does anyone have a solution for this problem, or know where I can get several pink gold plating solutions to try?

Thanks,

Joseph Cdeleted
Jewelry - New York, New York, USA


A. Hi, Joseph. Al Weisberg's "Gold Plating" chapter in the Metal Finishing Guidebook has a lot to say about what plating parameters to vary to bring out different tones of reds and pinks, and should be worth a read for this.

I haven't fully read Reid and Goldie's Gold Plating Technology =>
myself, but it has a lot of the info you need, like what shade each alloy metal drives the plating towards, a list of the standard colors in watchcase plating, etc.

Finishing.com's supporting advertiser, Technic and DeGussa are probably the major suppliers of precious metal plating processes, and can probably provide some pink gold plating solutions. Good luck.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey

Gold Plating Technology



How to do brown gold plating?

+++++++

Q. I want to do brown gold plating on a gold jewelry.
Can you tell me the bath make up and process, so that I get a brown gold plating.
Thanks
Dinesh

Dinesh Upadhyay
- Mumbai-India



Rose gold

December 13, 2011

Q. Hello

I'm trying to achieve a "rose gold" plating over silver.

I was told that the process is as follows

-electrolytic degreasing
-Phosphor copper bath
-Yellow gold acid bath
-Yellow Gold alkaline bath
-Final decorative bath of pink gold (acid)

This procedure would be correct?

Thank You

Alfonso Martos
- Oviedo, Asturias, Spain


+++++++

Q. Why does pink gold plating tarnish? Now I have a problem about plating. Silver ring plated with pink gold. It is beautiful. but when I show it in only 2 weeks, it is tarnishing. I think that is because of my sweat or pink gold plating process or chemical of pink gold plating.
Please! anyone help me solve this problem.

Jane
Samuthprakran - Thailand


July 29, 2008

Q. Hi
I have the same problem listed above. My rose gold plating tarnishes very quickly and in some polluted urban areas it tarnishes a green and black color. Does anyone know why my gold plate would tarnish green and black? Its terrible!

Perhaps the solution does not have enough gold in it --too much copper alloy?
How can I check the solution that my plater uses?

Thanks for the input.

Vanessa Zeena
Artisté - California


++++

Q. I have just started working with rose gold to make jewelry. When I solder it, it changes color and I have tried everything I know to make it pink again. Do you have any suggestions for me?

Rose Braunstein
hobbyist - Los Angeles, California, USA


++++

A. Dear Rose (et al),

Red gold alloys have a very high copper content and will form a heavy oxide when heated in air. A few suggestions may be helpful in minimizing the oxidation;

1. Apply a protective fire coat of boric acid and alcohol with a brush to the entire surface of the piece. Dry the coating with a soft torch flame before soldering.

2. Use a softer reducing flame (slightly richer in gas than air or oxygen). This will reduce the amount of oxide formed during soldering.

3. Try using a paste type soldering flux instead of the liquid solder flux. It will provide better protection during soldering and won't burn away as fast as the liquid fluxes. Apply more flux if needed during the soldering process.

4. The red gold solders have a very hard flow. Be careful heating the piece during soldering to avoid melting the piece you are soldering.

5. Pickle the soldered piece in a hot "Sparex" safety pickle (sodium bisulfate) solution. It may need a longer pickle time than normal to remove surface oxides.

A good source of excellent shop information for jewelers and jewelry manufacturers is "The Orchid Website", easily found on your search engine.

Good Luck & Best regards,

Jim Sivertsen
Refining & Alloys - Alden, New York

Boric Acid Powder




Sparex Pickling Compound


++++

A. Pink gold contains copper, your soldering removed the copper. I'm not sure but if you tried brushing with a copper soft brush, you may have some reddish color, otherwise you may consider plating.

Good luck


Cair Shishani
aircraft maintenance - Al Ain, United Arab Emirates



+++++++appended

Q. I'm a retailer , right now rose color gold is getting popular
But the problem is the rose gold piece will get a red tarnish .
Do you have any suggestion to make it tarnish proof?

Thank you very much

ma nee nuch

Maneenuch Anchit
owner of retail store - Bangkok, Thailand


+++++++

A. Are you talking electroplated gold or fine gold castings here? To achieve a pink or rose gold color the copper content in the alloy is more prevalent than normal alloying metals. In your region copper would not fare too well because of the weather conditions there. Is it possible that you could apply a clear lacquer coat to the jewelry for finish protection?

Mark Baker
Process Engineer - Syracuse, New York


+++++++

thumbsup2Dear Mr. Baker,
Thank you very much for the answer. If we lacquer it how long it will last 'til tarnished?
Anyhow I will let the factory follow your suggestion.
Very appreciated.
Ma nee nuch

Maneenuch Anchit
owner of retail store - Bangkok, Thailand


July 8, 2009appended

Q. Hi,
I work for a Los Angeles base jeweler and could greatly use some advise.
Our plater will rose gold plate items for us on sterling silver or base metal and within two weeks they are completely tarnished. Should we upgrade to 18K rose gold for plating or should we just quit all together? Any advice or suggestions would be greatly appreciated.

Carrie Hoffman
jeweler - Los Angeles, California, USA

July 10, 2009

A. Two problems: (1) "Rose Color" is too low an alloy to resist tarnish but a higher "karat" would not be rose. (2) The silver migrates right thru the gold, you must have a diffusion barrier between the silver and gold: either nickel or palladium.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

Editor's note:    
   Mr. Probert is the
   author of



July 12, 2009

A. Carrie

A couple of important questions. What thickness of gold did you ask for and what thickness did the plater supply?

Many jewellers request a 'flash' of gold for costume jewellery. The plating industry understands this to be enough plating to just give the colour required but too thin to be practically measured. The gold is so thin that the underlying metal readily corrodes. See letter 52510.

If this is the case, you should recognise that the price you pay is mostly for the process of plating as the actual gold you are buying is very little.

I suggest that for a quality product you will need about a micron of gold and the base metal items will require an undercoat - possibly silver or palladium as nickel is not permitted in many countries for skin contact applications.

Geoff Smith
Hampshire, England


July 19, 2009

A. Hi,
there are two reasons of tarnishing rose gold deposition on silver. First reason can be insufficient thickness of the deposition. If the deposit is a very thin, decorative flash of gold or alloyed gold we can observe migration/diffusion of silver atoms into gold in few weeks or even in few days. The gold deposit on silver must simply be thicker or have a diffusion barrier. The second reason can be the wrong gold plating process resulting mostly in low gold concentrate in the alloy.
Regards

JANUSZ LABEDZ
- WARSAW, POLAND


September 1, 2009

A. Hi,
I fully agree with the all above suggestions. Alternate way you can go for trivalent gold base rose plating or incorporate the anti-tarnish after rose gold plating.

Regards,

Gurudatta Thakur
- Mumbai, India


November 24, 2010

A. Hi, I've 37 years experience gold plating all sorts of different components. Amongst others, I used to manage an 18 ct rose gold process. We made, polished & plated corner mounts for a very well known luxury product company. The spec was 2.5 microns of 18 kt gold followed by 0.5 microns of 23.5 kt 3N.
Any customer requiring a top coat finish of 18 kt we would simply nickel, 3N gold flash, platinum 0.1 microns, 18 kt rose gold and finally immerse in an anti-tarnish solution. Worked every time for us on thousands of parts. Hope this is of some help to you.

Shaun Askey
- Shropshire, England


May 29, 2013

Q. Hi, I came across this site from Google. I recently bought a 18K white and rose gold wedding ring. After the jewellery shop did the name plating and polishing, I got the ring and keep inside the ring box and didn't open until about 9 days later. When I open, the rose gold part of my ring changed colour to very copper colour.

52562
The top is my ring where the rose gold part got oxidized, bottom is the original colour of the rose gold ring from the men's top part of ring.

The ring now is currently being sent to factory for checking. The branch manager told me that it might most probably due to electroplating part got oxidized or sweat or humidity, sweat is being ruled out because I haven't worn it (keeping it for the wedding). hHumidity? The weather in Malaysia is pretty hot. What I don't understand is the branch manager told me that electroplating can change the rose gold colour to lighter or darker, I doubt how true is it as my ring is suppose to be 18K rose gold. How can it be oxidized! Please enlighten me!

Lynn Chung
- Miri, Sarawak, Malaysia


June 5, 2013

A. Hello Lynn,
You had mentioned that the ring was kept in it's case and 9 days later it was discolored. There appears to be a problem with the plating deposit. This could stem from a few things. The alloy of the gold bath was way off, the gold plating was too thin, and migration through the gold plating occurred. It seems to me the plater would have masked off the white gold portion, and selectively rose gold plated the "stripe". If this was the case, discoloration due to thin plating would be a lighter gold color, not reddish. From what I see from the photos it seems the gold deposit contained too much copper, which is the main alloy for rose gold plating solutions. I was never a big fan of gold electroplating on wedding sets. Gold plating does not last very long when rings are worn every day.

Mark Baker
process engineer - Malone, New York


June 11, 2013

Q. Hi Mark,
The ring is actually ready made, so all the while there is no discolouration problem until it was being sent to its factory for polishing. And since I got the ring, I kept it in its' case and up to 9 days later only I open up the box and notice such discolouration, it may have discoloured even earlier. My wedding bands are pure 750/18K, they are not electroplated gold. But why do you need to plate a 18K rose gold? The jewellery shop explained to me that the factory actually plated a layer to enhance the rose gold colour but never did they know that it will be oxidized, I doubt how true are their words. They have remove that layer of plating and the ring is back to its' original rose gold colour. However, I got them to custom make a new ring for me.

Lynn Chung
- Sarawak, Malaysia



24kt gold colours 4n and 3n

April 5, 2014

Q. I am a goldsmith from India. I have to colour my 20 carat gold jewellery. I came to know about 3n-4n gold colours which can be achieved by changing some parameters. How to achieve it? Kindly reply

padmanava jethy
goldsmith - india

April 2014

A. Hi Padmanava. Is there a typo in your inquiry as you mention 24 ct in your title and 20 ct in the text? I don't see how 24 kt gold can be anything but pure yellow, although I'm no expert.

3N is Yellow, 4N is Rose (Pink). The previously referenced "Gold Plating Technology" by Reid and Goldie has whole chapters on the topic of gold coloring / color gilding / watch industry applications. Good luck.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey


April 13, 2014

Q. Thanks a lot. My jewellery is of 20 carats and to achieve 24 ct colour on it I have started electroplating the jewellery. One supplier told me that 24 ct colour, 3n and 4n could be achieved in the same solution by changing some parameters. I wanted to know the meaning of 3n and 4n which you have mentioned. What are the parameters, i.e., voltage or electrocleaning time or anything else I wanted to know. Thanks.

padmanava jethy [returning]
- cuttack, odisha, India


April 2014

A. Hi again, Padmanava.
"3N" is the color of an 18 ct gold which contains 750 PPT (parts per thousand) gold, 125 PPT silver, and 125 PPT copper.
"4N" is the color of an 18 ct gold which contains 750 PPT gold, 90 PPT silver, and 160 PPT copper.

Whether your supplier's gold plating solution can produce a 3N and a 4N color through changing some simple parameters is something that I would not know. I have no idea of its composition, and there are countless formulations. For the same reason, I don't know the suggested operating parameters for your supplier's gold plating solutions. You have to get this information from them. Sorry.

If you know the general constituents of the gold plating solution, Reid and Goldie's book might help ... but it is 630 pages, and not something I can summarize in a paragraph or two :-)

Luck and Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey

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