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Does etching galvanized pipe remove the galvanization? [California] 

November 12, 2007

I am producing some outdoor products that is made of dipped galvanized pipe that is powder coated. I was told that in order for the Powder coating to stick to the galvanized pipe it has to go through a process of washing the pipe with a chemical. I was also told that this process hydrochloric acid wash would remove the galvanization? Is this true and if it is true is there another chemical that can be used?

Mauro Bave
industrial user - Oceanside, California, USA

Hello, Mauro. The correct answer is that the galvanizing should be treated with a phosphatization process, not removed with HCl. Good luck.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

I am not a painter, so take this with a grain of salt. Galvanized needs a special primer, which used to be zinc chromate based. Note that chromates and not allowed in more and more products. I do not know if an acid wash primer is suitable, but it will not remove much of the galvanize if it is suitable. As Ted said, HCl etch will strip and zinc phosphate is a good process.

James Watts
- FL