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topic 9975

Rhodium plating problems and troubleshooting


(2001)

Q. In my humble opinion, Rhodium plating has always been a difficult process to the jeweler. I have started Rhodium plating about a month ago, and I am experiencing some difficulties when I plate with Rhodium on 18K white gold. I am abiding to the rules of Rhodium plating such as: good buffing, electrocleaning, etc. However, when I nickel plate prior to Rhodium, I notice on certain pieces grey, matt, dull areas as burnt areas. I give 120 °F and 2 volts to the rectifier and 2 minutes timing.

What in your opinion is causing this?

Joseph Tanti
Josies - Malta


(2001)

A. I think 120 degrees is low for a nickel bath, but why are you nickel plating your 18K white gold before rhodium? You should get excellent results plating rhodium directly over gold and it is a good idea to avoid nickel on items which will be worn against the skin.

Neil Bell
Red Sky Plating

supporting advertiser
Albuquerque, New Mexico
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Rhodium Plating System

(2001)

A. Why do you use nickel plating over 18K white gold?

Its an old technique!

People prefer nickel-free jewelry nowadays as science revealed that nickel can cause skin-cancer if worn constantly.

After electrocleaning, give the article an 'acid-wash' followed by dipping it in rhodium-bath.

Avoid using nickel. It's not recommended.

Sudeep Sethi
- Indore. MP, India


Nickel and the Skin

(2001)

thumbs up signThere is no question that a lot of people suffer a skin allergy to nickel, Mr. Sethi, and I agree with you that nickel doesn't belong in jewelry. But I think your assertion that "science revealed that nickel can cause skin-cancer" is an overstatement. Can you reference any published document that asserts this? Thanks.

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


(2001)

A. Don't forget a pure gold underlayer for the Rhodium.

Mike Brewington
- Salisbury, Maryland, USA



Acid wash before rhodium plating

(2001)

Q. Mr. Sethi suggested an "acid wash" prior to rhodium bath. Please could you kindly explain further what do you mean by 'acid wash'. How is it prepared and what type of acid is used for this type of wash. Does the acid wash need to be warmed up? To what temperature? Do you need to rinse again with distilled water after the acid wash?

Thank you in anticipation.

Joseph Tanti
Josie - Malta


(2001)

A. Hi,

First do electrodegreasing (cathodic) then 2 water rinse then 5-10% sulphuric acid rinse (room temp) then dm water rinse and rhodium plate. And much brilliant white finish product available are Degussa TD, Heraeus K-20 or Metakems Dekor bath.

Good luck,

Qutubuddin Saify
- Ajman, U.A.E



Inconsistent plating thickness on rhodium plated ring

(2002)

Q. I am studying about plating rhodium method. I plated a silver ring but I established different thickness areas on the ring. How can I solve this problem?

Serkan Ceylan
Sakarya University - Erenler, Sakarya, Turkey


(2002)

A. Hi, Serkan. Check into Faraday's Law, which tells us that the plating deposits exactly where the electricity goes, and in exact proportion. Then check into Ohm's Law, which says the current is the voltage divided by the resistance -- and you will see the tough truth that you would need to get the anodes to conform exactly to the ring to get the resistance the same to all spots, and thus the current and thus the plating thickness. Then you'll have to decide on what compromises to make between perfect distribution and practicality.

For some plating processes, like acid copper, there are some addition agents that are of some help in evening out the thickness distribution, but I don't think any such agents work in rhodium plating. Good luck!

Regards,

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



Nickel plating under rhodium plating

July 26, 2012

Q. 1 - Can I use nickel plating before rhodium to get better result?

2 - How to get more white brightening in gold plating by rhodium?

thanks

yaser abdulrahim
gold - cairo, egypt


July 26, 2012

A. Hi Yaser.

1. Yes, nickel plating can be done before rhodium, but due to widespread nickel allergies and some countries outlawing nickel plating in jewelry; white bronze before rhodium would be better. That is, of course, if you don't plate directly onto the white gold as Neil Bell suggests.

2. Sorry, I haven't personally heard of brightening a gold plating bath with rhodium additions.

Regards,

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



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