
plating, anodizing, & finishing Q&As since 1989
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Zinc Plating has white & red rust without a cause

Q. One of my customers received Zinc Plating Bolts from us in White and Red Rust condition but we are not sure how this has happened. The bolts are packed inside Water proof packing and this packing had been tested in our labs before implementation.
All the zinc plated bolts have also been tested via SST method for 48 hours and no rust was found. Even our old stock lying for more than 2-3 months have no rust on them.
The coating on average was 10 to 15 microns.
- Kolkata West Bengal, India
November 14, 2023
A. Hi Arvind.
We don't have enough facts to support anything but wild guesses, so mine is the parts were wet when they went into the waterproof packing.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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