Metal finishing Q&As since 1989

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Mechanism of a cationic electrodeposition paint system

2004

Problem 1. Need specific information regarding the mechanism of function of the anodes in a cationic electrodeposition paint system. Problem 2. Of the reactions I have seen thus far on my search through the internet on the coating process I do not see where the formation of acid in any steps.

My information shows that there are two major reactions:

1. H(2)O + 2e- -> H(2) gas + 2OH-
2. R-NH(3)+ + OH- -> R-NH(2) + H(2)O

I see no formation of acid into the E-coat bath. Are the formulas incorrect?

Anyone with more detailed information about the mechanism of a cationic electrodeposition paint system including the function of the anodes and anolyte please send me this info.

The anolyte is non-acetic acid [on eBay or Amazon]. It is a recirculating DI system that purges once a certain conductivity is reached.

Jeff Ehlenfeld
Paint Line Technician - Georgetown, IL, USA

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Look at www.clearclad.com/clearclad_resources/ecoat.htm. This gives a good explanation as to how e-coats work.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2004

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Dear Jeff:

The acid is generated at the anode. The reaction is: 2H20 -> 4H+ + O2 + 4e- Hope this helps.

Regards.

Gurvin Singh
Mohali, Punjab, India
2004