finishing.com -- The Home Page of the Finishing Industry

HomeFAQsSuggested
Books
Help
Wanteds
Advertise
on this site
FORUM
current topics
Live! From beautiful Pine Beach New Jersey: Welcome to the world's most popular metal finishing website

topic 54579

Gold necklaces turn black after electrodeposition




March 16, 2010

We are a supplier of gold jewelry, our customers are complaining because one month after they receive their product the gold turns black, the electroplating technician does not know why, but I suspect that the bath is contaminated, would you please help me to find out how to use the hull cell to verify the bath or another way to find out if the bath is contaminated?

Bertha Bosch
Quality Manager - Naucalpan Mexico, Mexico


First of two simultaneous responses -- March 18, 2010

Bertha,
The best way to tell if the bath is contaminated is to have the bath run for metallic contaminants. If you can't do it in your shop, your supplier should be equipped to do it. If they won't, an independent lab can. Normally they check for copper, nickel, zinc, iron, and lead. You also want to make sure the gold is at the correct concentration and the right deposit thickness.
Another option is to set up a fresh liter gold bath in the lab with the exact make-up (scaled down of course) as the bath on the wet floor. Plate a few small pieces, send them to your customer for approval. Hull cells are good, but leave too many problem possibilities (mainly for gold baths). Good Luck!

Mark Baker
process engineer - Malone, New York


Second of two simultaneous responses -- March 18, 2010

What is under the gold? If silver, brass, or copper, then it migrates right thru the gold and looks black on top. You must have a diffusion barrier of either nickel or palladium.

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina
Editor's note: Mr. Probert is the author of Aluminum How-To / Aluminio El Como
and co-author of The Sulfamate Nickel How-To Guide



If you have a question in mind which seems off topic, please Search the Site

ADD a Q, A, or Comment on THIS topic START an UNRELATED topicView CURRENT HOT TOPICS

Disclaimer: It's not possible to 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 may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & Devices


©1995-2019 finishing.com, Inc., Pine Beach, NJ   -   About finishing.com   -  Privacy Policy
How Google uses data when you visit this site.