Metal finishing Q&As since 1989

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7 Tank process, surface preparation process

Q. Dear Sir/Madam,

We are setting up a fabrication shop manufacturing tanks, etc. We are need information 'bout 7 tank process or the alternative method for surface preparation. Please give us following information. 1)Details of 7 Tank process 2)The chemical composition & temperature of each liquid in all tanks. 3) The Approximate time interval for sheet-metal to be kept in each tank for cleaning / coating etc. Please write me or tell me any site or webpage where we can get all this information.

Thanks and regards,

Sachin Pawar
surface preparation - Pune, Maharashtra, India
2004

A. I'm guessing that you are referring to zinc phosphatizing, Mr. Pawar. I would suggest that you search our "must have" booklist or ASM International's booklist and get a book on the subject, or at least a metal finishing book that has a chapter on the subject. Good luck!

Organizing information into orderly book-like presentation entails man-years of effort as any author will tell you, and every attempt at a viable economic model for publishing book-like documents on the web has been a dismal failure. As my partner, Tom Pullizzi, first described the internet's problem: "Infinite demand at zero cost, zero demand at infinitesimal cost". So, while forums like this one that quickly answer a brief, specific, carefully-targeted question have proven to be viable, web pages that resemble books in presenting technical information in clear, systematic, tutorial progression simply don't exist, and searching for them is a waste of time.

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

A. As Ted suggested, begin by reading a chapter or book on phosphating. In addition to those in the above links, "Phosphating & Metal Pretreatment" [on Amazon or AbeBooks] by D. B. Freeman is good. This will certainly give you the basics as well as an idea of the necessary equipment. For trouble-free setup and operation (as far as possible), follow the technical advice of the phosphating chemical suppliers. See "Suggestions for start up of zinc phosphating business" letter #27367. Proprietary chemicals include accelerators, surfactants, grain modifiers, rust inhibitors and (perhaps) sludge inhibitors. Suppliers in India include the internationals Henkel and Chemetall (Oakite) and a local company, Guardian Anti-Corrosives Private Limited. In addition to proven chemicals and procedures, they have troubleshooting expertise, laboratories, etc.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.