plating, anodizing, & finishing Q&As since 1989
Spots appear on zinc plating after 48 hours under normal environment
April 21, 2010
Base metal is 4130, with zinc plating. Being put in stock in plastic bags for 2 or 3 days, corrosion spot appears on the surface. Other parts were plated at the same line does not have this problem. Even several replatings can't solve this problem. Cyanide plating bath, 8-10 µm thickness, Pavco trivalent chromate. The parts were replated at another plater, alkaline plating bath, 10um, Yuken trivalent chromate, but with same issue. What is the root cause?Sharon Luo
Supplier chain - Shenzhen, GuangDong, China
First of two simultaneous responses -- April 23, 2010
Pitted parts, cold shuts and bad alloy comes to mind.James Watts
- Navarre, Florida
Second of two simultaneous responses -- April 26, 2010
Is it a cast iron, may be its too porous, I would suggest to have an acid zinc plating, then heat it and then passivation followed by a silicate sealant.
Hope this would help to achieve better corrosion protection.
plating process supplier
April 26, 2010
Sounds like you are plating castings to me. Correct?
electroplater - Galva, Illinois
April 28, 2010
What happens if you do NOT bag the part? Are the parts dry when you bag them? Have you tried a different supplier of bags, or material? Do you bag other parts without issue?
- Colorado Springs, Colorado
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