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Letter 27047 Risk of not phosphating? [Mexico]++++ Hello, I will like to know if you can help me about the following question: I work with powder coating, but want to know what are the risks of not using the phosphate in the pretreatment process for metal parts? Thank you very much for helping me. Eliseo Izquierdo
++++ 'Work with' is a little vague, Eliseo. Without knowing the application and environment, and the type of powder coating, we really can't tell you whether it NEEDS phosphate or not. But phosphatizing is always a very good idea and should not be omitted unless the item is too difficult to phosphate, and will see only interior exposure, and is otherwise well prepared. You might want to consult a book about phosphating like R.
Rausch's book
"Phosphating
of Metals" or Samuel Spring's
"Preparation of Metal for Painting
++++ Dear Sir, The general rule of thumb would be as follows to phosphate or not. For powder coated items that are to be sited outside (exterior) you will use a polyester powder. Having paid a little extra (poly vs e/p) it is wise to zinc phosphate. This is a preventative action in case the item gets damage (scratched) the phosphate will then prevent in the short term corrosion (rust creep) between the metal and powder. For epoxy polyester powder coated items destined for internal use - iron phosphate is surfice - we class it as a very good surface cleaner - it will/may improve the adhesion of the epoxy polyester powder (?). Most coaters would only use this treatment if it is specified by the customer - why add to your processing costs? Hope this answers the question you posted.
Dear Reader: please choose what you want to do--
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