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Need procedure for Yellow Passivation on Zinc

I am looking for a Step by Step Procedure for doing Yellow Passivation on Zinc Die Cast Components along with list of machineries required to do the same. Thanks

Sushil Mandawewala
Inhouse Plating Shop - Jamnagar, Gujarat, India
October 12, 2008

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Simple. Buy the material from a reputable vendor and they will give you an operations sheet and guidance on setting the system up.
Do not try it on home brew until you have a lot of experience with a proprietary solution.

James Watts
- Navarre, Florida
October 14, 2008

If you do not wish to contact a manufacturer of these materials, I strongly suggest that you get a copy of a book which describes the process. Conversion coating of zinc castings have various procedures depending upon the alloy. This web site offers/links to sources for suitable references.

Gene Packman
process supplier - Great Neck, New York
October 15, 2008

Thanks for the response. I am going to buy the chemicals from reputed supplier and I have also given them samples for trials. In the meantime I thought of taking expert advise from this site so that I can verify the process suggested by the chemical supplier.

Sushil Mandawewala
- Jamnagar, Guajrat, India
November 9, 2008

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Hi, Sushil. The basic steps will probably be mechanical prep (perhaps vibratory finishing), followed by alkaline cleaning (mildly alkaline to be suitable for zinc), followed by mild acid dip, followed by chromate conversion coating, with good rinsing between each step. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
November 13, 2008