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7-tank phosphatization yields rusty, patchy, yellowish work

Q. Dear Sir,

We have powder coating plant, we are preparing surface prior to coating, i.e., phosphating; we are using seven tank process for it. We are coating HRC, CRC. hot rolled angle, etc. Our problem is that we are not getting proper finish after phosphating: some rust and white & yellow patches are coming after phosphating. We are using phosphorus base chemical. Please suggest us proper method.

regard

Pravin Kulkarni
- Nashik, India
September 1, 2008

September 2, 2008

"Phosphating of Metals"
by Werner Rausch
phos_rausch1991
on AbeBooks

or eBay or

Amazon

(affil links)

"Phosphating & Metal Pretreatment"
by D.B. Freeman
phos_freeman1991
on AbeBooks

or eBay or

Amazon

(affil links)

Hi, Nashik. This is a broad question! Have you been successfully phosphating all along and this is a new problem that has suddenly cropped up, or have you not successfully phosphated yet? You ask for "the proper method", but whole books are written to explain what the proper method is.

But to the extent that you can tell us exactly what you are doing -- like formulation of phosphatizing bath and operating temperature -- someone may be able to at least identify some things that are wrong. Good luck.

Regards,

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

The proper place to start is with your vendor. If you are using a home brew, no one can help you.

James Watts
- Navarre, Florida
September 2, 2008

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

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