White powder defect on Black Passivation on Acid Zinc Plating
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.
Vinod Kakar Pervesh Rasayan - Faridabad, Haryana, India
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 Mahmud Univ of Science - Penang, Malaysia
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