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Blue stains in zinc plating

March 26, 2009

My process is as follows (I will start from zinc) :
1.- Zinc tank 20 mins then goes to
2.- Water with Clorhidric Acid solution PH 2.8
3.- Nitric Acid with water PH 2.8
4..-Water
5.-Water
6.- Color
7.- Water

After step number 2 or 3, blue stains appear and I cannot eliminate this problem.

Can you help me?

Sergio Samaniegpo
Owner - Mexicali, BC, Mexico

April 6, 2009

Sergio,

A little more information please. What type of zinc process are you using (alkaline non cyanide, cyanide, acid chloride, alloy) and when you say color do you mean chromate conversion coating.

Even though the problem is after the zinc plate it would be best to know the whole process cycle as well as the parameters of the zinc bath and the substrate being plated.

Gene Packman
process supplier - Great Neck, New York

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