Metal finishing Q&As since 1989

-----

Hard chromium on brass

Q. I am looking for main difference(s) between hard chromium plating process on steel and on brass.

Kourosh Shirani
I am a researcher - Iran
March 1, 2008

---

A. Your question is vague, Kourosh, but I would say that the biggest difference is usually thickness; if you apply chromium to hardened steel it can be reasonably thin, whereas if you are putting it on brass it must be quite thick before it can achieve anything useful. Please say what you are involved in and what motivates the question, then we may be able to understand it better. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 4, 2008

A. Another basic difference is that you should not reverse etch the brass in your plating chrome tank because it will become contaminated with copper which causes problems. Clean it thoroughly to a water break free surface, dip it in 20% sulfuric and plate on forward polarity. Enter the bath live.

Guillermo Marrufo
Monterrey, NL, Mexico
March 5, 2008

A. Hi, do you mean the pre treatment processes for brass and steel?

For steel: pumice clean, waterbreak test, sulfuric etch, chrome etch, then live into chrome vat and plate as required ,

For brass: pumice clean, waterbreak test , and pre-treat as the guy said in the message above -- 20% sulfuric .

Hope this helps .

Jay Smith
- Essex, UK
March 17, 2008