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  for Metal Finishing since 1989
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Zinc brightener

2005

Hello!
I am a metallurgy engineer. I have a cyanide zinc electroplating industry.my process stages is:
oilccleaning-acidwashing(sulforic acid)-cold rinse-zinc bath-cold rinse-chromating bath(blue-yellow-green-black).my bath brightener buy from canning company.
my bath composition: zinc cyanide-sodium cyanide-NAOH.the anode is zinc(99.99%)
1.what is the all roles of brightener in bath?(and it's equations with other materials and specimens in the zinc bath)
2.please describe the chromate reaction and it's equations.
3.why do I see a iridescent shadow in gree chromated pieces after dry?
4.which material do create the green color in green chromate coating?(and other colors like black-blue-yellow)
5.why do the color clear from surface after chromate?

Amir Khakzad
Mottahed zinc electroplating - Tehran

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Your questions, while relavent, would be quite lengthy to answer. I would suggest you purchase or otherwise secure some books on the subjects of electroplating and conversion coating. Short chapters on these are available in the Metal Finishing Guidebook and in "Products Finishing" (magazine) Directory Issue.

Gene Packman
process supplier - Great Neck, New York
2005