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Delayed gold/yellowing on non chromated zinc plated test panels

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Q. Good day

Alkaline Non Cyanide Zinc plating.

Recently while running Hull Cell ⇦ ? tests I'm finding that some sample hull cells are developing a uniform yellow/gold layer after a day.

This does not happen after the panels are fully dried. They are not chromated.

No other unusual defects are seen at the time the parts are finished.

Any ideas on what this could be are appreciated.

Boris Siljanoski
- Perth, Western Australia
April 8, 2025

A. Hi Boris,

Are you using brass panels or steel ones? If using brass panels. and the zinc is quite thin, it could just be a matter of seeing the brass due to diffusion.

Luck & Regards,

ted_yosem
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Boris,

1. Try to use zinc coated steel panel then run hull cell panel. Before you put in hull cell strip zinc in conc. HC; follow up rinse and put into hull cell to plate.

2. make a new alkaline zinc solution, run panel

3. If #2 test results no yellow color after few minutes means contamination your rinse tank or zinc bath.

Popatbhai B. Patel
electroplating consultant - Roseville, Michigan

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