As an Amazon Associate & eBay Partner: we earn from qualifying purchases
Mr. Rogers: "Look for the Helpers. You'll always find people who are helping."

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

-----

Black spots after copper coating

"Electroplating and Electroless plating of Copper and Its Alloys"
by N. Kanani
copper_plating_kanani2003

on eBay or Amazon
or AbeBooks

(affil link)

"Copper & Copper Alloy Plating"
by R. Pinner
copper_plating_pinner

on eBay (rarely)
or Amazon
or AbeBooks

(affil link)

Q. Dear Sir,
I am getting black spots after copper coating of carburising treated low carbon parts. Kindly guide me for correction

Jay Sona
Metlab, Supplies Quality, Heat Treatment, Projects - Rajkot
September 22, 2025

A. Hi Jay,

Frequently, 'cyanide bleedout' can be a cause of spots and discolorations.

I and the readers are happy to help, but it is rarely the case that a given problem has a single possible cause. To expect that would be like phoning a doctor that you have a fever and expecting him to tell you exactly what is causing it.

Please send a picture of these spots, and tell us a bit more about the processing, and hopefully we can be more definitive.

Luck & Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted can be retained for immediate
answers or long term project help

(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: