No registration or passwords; no pop-up ads -- just aloha, fun, & answers.
(as an eBay Partner & Amazon Affiliate earns from qualifying purchases).
Home /
T.O.C.
Fun
FAQs
Good
Books
Ref.
Libr.
Advertise
 
Help
Wanted
Current
Q&A's
Site 🔍
Search
pub  Where the
world gathers for metal finishing
Q&As since 1989



-----

Rhodium Pen Plating Problems

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

red sky plating banner


Q. Hi,

I want help to know that I have bought pen plating machine from Dubai with rhodium solution when I plate on 22k read made jewelry it looks dark and it burn's, I have try to use 2V to 1.5V but still it give me same problem. I have also well cleaned the jewelry then I'm doing rhodium plating. I have spoke to my supplier in Dubai he said I don't know how to solve the problem.

Please help me.

Dipen Pattni
Dipen Pattni
jeweler/goldsmith - Dar-Es-Salaam, Tanzania
2002


A. Dear Mr. Dipen,

1. electroclean your job or ultrasonic and see there should be no water breaks
2. water rinse
3. water rinse
4. 5% sulfuric acid dip
5. water rinse (all water rinses should be of d.m water)
6. pen rhodium (keep voltage 5-6 volts , soak your tip of pen 1 hour before plating , roll around the tip gently and don't apply pressure on tip during operation and try to keep tip always wet)
7. water rinse
8. water rinse
9. dry

Hope this tips will do well.

Qutubuddin Saify
Metachem - Ajman, U.A.E.




Q. Dear Qutubuddin,

Thanks for your advise, What you have advise me I have done same.

I have ultrasonic and I have done
1. D.I.water rinse
2. D.I.water rinse
3. 5% sulfuric acid dip
4. D.I.water rinse

Then rhodium plating still it does not look bight. My rhodium solution is very fast, if I use more then 5V on matte or mirror surface it burn the plating. I'm moving rhodium pen fast. Also with 2V I can plate bit fast. I think my solution is not good.

Thanks,

Dipen Pattni
Dipen Pattni
jeweler/goldsmith - Dar-Es-Salaam, Tanzania
----
Ed. note: These postings from Dipen are from a long time ago. Some of his recent work is amazingly beautiful!

A. I think you should control that the voltage you put in your pen plating machine is real.
For example there are a lot of machine that you put on 3 V but if you rally control tension you can test 1 or 2 or 5 V.

Bye Giacomo

Giacomo Rossi
- Arezzo, Italy
June 10, 2008





Q. Hi,

I'm a local jewelry manufacturer from India.Since last few days I have started seeing problem of rhodium on prong tips on any of my piece turning black.The rhodium is done by pen plating method.I first gold plate the pc to enhance its yellow colour & then pen plate the tips with rhodium (Ultrabright by Legor).The voltage at the time of pen plating is 7 to 7.5.
please suggest some remedy!

Joshua Alfred Baskin
Jewellery manufacturing - Noida, UP, India
2006


A. Hi Joshua,
Sounds like you have severe burning. Soak the pen plating tip in the solution for at least 15 minutes before plating. Move quickly on the part, staying in one place too long can cause burning. Keep the tip wet. I would start with a fresh rhodium pen plating concentrate to rule out any solution problems you may have. If the Rhodium metal concentration is too low, burning will occur. The voltage is usually predetermined by your supplier, check to make sure it's correct. Good luck!

Mark Baker
process engineer - Malone, New York


A. Hi Joshua,
Please ref. discussion below in this topic. Your problem and suggestions/remedies are identical.
Further keep two brushes -- one always keep dipped in DM water to wet/clean the surface to be plated and the other to plate. Adjust the distance between cathode and anode by trial and error method to suit your need. Apply brush one way and not reverse.
Regards

t k mohan
T.K. Mohan
plating process supplier - Mumbai, India




Multiple threads were merged: please forgive repetition, chronology errors, or disrespect towards other postings [they weren't on the same page] :-)



Q. I AM A JEWELRY MANUFACTURER IN GREECE AND I AM USING THE RHODIUM PROCESS (BY BATH) FOR OVER SEVEN YEARS. NOW I PRODUCE SOME NEW MODELS, AND I MUST USE THE PEN RHODIUM. WHATEVER I DO I CANNOT HAVE GOOD RESULTS -- I GET A GREY COLOUR, BUT I KNOW THAT MY ALLOY HAS A GOOD WHITE COLOUR. I WANT SOMEONE TO GIVE ME AN ANSWER ABOUT WHAT I HAVE TO DO.

TSITSILAS CHRISTOS
JEWELRY - THESSALONIKI, GREECE
2006


A. First of all, tell us what you are doing. Secondly, rhodium is not an alloy but a pure metal. Thirdly, have you tried a Hull Cell panel test and if so, does it come out as you want it to?

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


A. You had mentioned you had a rhodium plating bath. Are you using the bath plating solution for the pen plate application? If so, what is the Rh metal concentration in the bath? Because you are experiencing a greyish color that tells me the rhodium and / or sulfuric acid concentration is too low for pen plating. What voltage are you using? That may be too high. I would contact your rhodium supplier and have them sell you a pen plate concentrate (ready to use), and have them fax you a data sheet with clear instructions. Some suppliers will add a little phosphoric acid to make the finish somewhat whiter. Good luck!

Mark Baker
process engineer - Malone, New York


A. Dear Christos
The chemistry of bath plating Rh and Pen plating Rh is entirely different. Generally bath Rh conc. is 2 grms/ltr and pen plating sol'n has high (many fold) conc. of Rh.
Voltage used is higher than the plating voltage.
Variation of distance between the anode (in this case the clip) and the cathode (the pen),the voltage applied, the conc. of metal -- all play important roles. The expertise of applying the pen (brush) is also important.
Please explain the procedure you follow (with details), and maybe I can explain better.
Regards,

t k mohan
T.K. Mohan
plating process supplier - Mumbai, India




Can you please tell me if by using pen rhodium/Full rhodium/ Colour process there will be no weight loss or weight added to jewelry?

Lalit Aggarwal
- Philadelphia, Pennsylvania, USA
2007


A. Hi Lalit. Etching reduces the weight of jewelry and plating increases it, but ...
Any etching of a precious metal is going to be minimal, and with rhodium costing up to $12,000 per ounce several times in the last decade or so, you can be confident that the weight applied is incidental. Thicknesses are often in the 0.1 micron range; you are welcome to do a weight increase calculation based on this, but I think you'll find that my dismissing it as 'incidental' is justified.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey




Q. Hello sir,
I am local jewellery manufacturer in India.
I have a problem when I do rhodium; it turns black and I also want to know pre-process of pen plating and post process.

Satya Narayann Verma
plating shop employee - Agra, up, India
October 18, 2011




Q. Please suggest correct solution for Dip Rhodium bath and Pen Rhodium separately. Also cleaning solution.

R Ravichandran
diamonds - Bangalore India
March 1, 2013



Rhodium Plating Solution
on
Amazon

(affil links)

A. Hi Ravichandran. The basic ingredients are about 2 grams per liter rhodium sulphate plus sulfuric acid -- but please contact a plating process distributor in Bangalore and they will offer you the proprietary solutions from Degussa, Technic, Cohler, Davis-K or others. Usually there will be a starter solution and a maintenance solution. Pen plating solutions are sometimes more concentrated and sometimes contain thickening agents, perhaps fumed silica or barium sulphate -- I don't know.

This is not something that you usually make yourself; first, because a lot of development effort may be required; second because you need to work with a knowledgable and well equipped lab to troubleshoot the inevitable problems and unless you have that exotic equipment yourself you'll need them to use theirs; and third because rhodium is so terribly expensive that you can't waste any in trial and error. Get back to us if you have further questions.

We have 60,000 threads on line here on 60,000 topics, so please post your questions about cleaning formulations on a more applicable thread. If the threads wander too far, no one will be able to find anything :-) Good luck.

Regards,

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 1, 2013


A. Brightener for rhodium plating is available in the market. You can contact some of the companies in Kolkata.

Partha Das
- MUMBAI, maharastra, India
September 12, 2013




Q. I have a casting factory in Mumbai. My only problem is when I do rhodium on my stones with pens some of the prongs turn grey. Why is it I am facing problem of [lack of] whiteness? I am using Legor ultra bright pen rhodium. Can please someone help?

manish tamka
- mumbai maharastra India
April 1, 2015


----
Ed. note: Reminder, no suggestions of different brands of proprietaries please -- huh? why? :-)




(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

 
Jobshops
Capital
Equipment
Chemicals &
Consumables
Consult'g, Train'g
& Software


About/Contact  -  Privacy Policy  -  ©1995-2024 finishing.com, Pine Beach, New Jersey, USA  -  about "affil links"