
plating, anodizing, & finishing Q&As since 1989
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White powder defect on Black Passivation on Acid Zinc Plating
2006
We are facing a problem of white powder developing on Hexavalent black passivation on zinc plated components. The problem occurs only during monsoon season when their is moisture in air.
Kindly help,
Pervesh Rasayan - Faridabad, Haryana, India
2006
It could be Zinc Oxide (ZnO). Normally zinc would oxidise at temperatures above 400 °C. But maybe with the exposure of moisture and catalysts, oxidation is possible. Find ways to avoid contact with moisture.
Shahrom MahmudUniv of Science - Penang, Malaysia
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