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Brown stain on white e-painted parts

April 30, 2011

I run an electrocoating process; sometimes what we call brown stain will show trough the white paint, doing a lot of test, It will only go away if the phosphate is not applied. All the parameters are in range and will be the same as when we run with no problems. Also in the same day I will have a mix of good and bad parts. I have done the water break test and is negative, so I'm assuming they are clean.
Also I have lowered the voltage thinking it might be too much for the load but didn't work.

Any ideas of why is this happening ?

Norma Zepeda
electrocoating supervisor - Mexicali, Mexico

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