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Q&As since 1989


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Chromate class 3

2007

I own a small machine shop and would like to do my own chromate class 3 yellow.
Can anybody tell me what the process is, equipment needed, good books on plating.

thanks,

Walter Mclain
machine shop - Lemitar, New Mexico, USA

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Yes I have a lot of books on the subject and I've always been interested in starting up a small machine shop so if you could recommend some books, we can both get started on exchanging businesses. I wish it were only that simple! Hexavalent chromate materials are toxic and hazardous. They must be disposed of in accordance with the law and the Clean Water Act - you don't do pouring coolant down storm sewers do you? Last year OSHA lowered the permissible exposure limit for such chromate materials 10-fold - are you going to monitor your workforce to these new more stringent guidelines. Good luck finding everything you should need in a single book or two. Rather than bury you with volumes upon volumes I have another proposition: I promise not to trivialize your job by assuming that it can all be learned by reading a book on it if you promise not to insinuate the same about mine!

Milt Stevenson, Jr.
Syracuse, New York
2007

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While your point is certainly valid, Milt, your response is harsh; maybe you're having a rough day. There are many things that people learn to do with little formal training and without permitting, like painting, wall papering, laying tile, and cooking their own dinner -- even though there are professionals in those businesses. A person not familiar with chromate conversion coating isn't going to know how much is involved until he asks :-)

Plus, in-house chromating is hardly unknown. I'd say that more aluminum sheet metal houses probably chromate in-house than farm it out. And now that hex-chrome-free TCP coatings are widely used, I'd expect the percentage to not decline.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

adv.