No passwords, no registration, no paywalls, no popups, no AI

As an Amazon Associate & eBay Partner we earn from affil links

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

Search our quarter-million Q&As

Home of the finishing HOTLINE since 1989

-----

Difference between Yellow, Green and White Passivation

Dear All,

I would like to know the difference between the various passivation used after zinc plating. Currently we are using yellow passivation and want to shift to white passivation. The base metal is Galvanised Iron sheet, manufactured by pressing operations.

I. Vijayasankar
- India
2006

2006

Sir,
30 years ago I did fundamental work on hexavalent chrome to protect hot dip galvanized work in Canada. First we found which worked better chromic acid (CrO3) or sodium dichromate (Na2Cr2O7). Then we used various acids to control pH to the correct pH. From our work we found that sulfuric acid pH control gave gold, nitric acid gave light yellow, hydrochloric acid plus acetic acid ⇦ on eBay or Amazon [affil link] gave clear with a slight sky-blue where the chromate quench had not dried and did not fully drain. The last formulation was by far the best looking and always passed the Canadian government 40 hour salt-spray test.
Regards,

Dr. Thomas H. Cook
Galvanizing Consultant - Hot Springs, South Dakota, USA

adv.
this text gets replaced with bannerText

Sorry! Finishing.com is temporarily Read-Only.
Ted Mooney is retiring but I have several offers to take it over.
We're working hard to make sure we find it the best new home.

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: