E-coating vs. Powder Coating vs. E-coating Plus Powder Coating

A. Theoretically, they are both electrodepositions. Both achieve the same end - an organic coating on a metal substrate. Only the method of transferring the organic layer is different. In powder coating the powder particles are charged. In E-coat the liquid is charged and an electrochemical reaction deposits a film. Both have to be baked for crosslinking. Both are available in epoxies and PUs. Both have their own advantages and disadvantages.

To compare the parameters you will need to match the technologies. Epoxy or PU. That is fairly complex to be answered here.

A. Hopefully, you will get some help here ... and you can contact the Powder Coating Institute and vendors such as Tiger Drylac and Martex to see what literature they can offer, Michael.

But personally if I had 30 million dollars in sales at risk in these circumstances, I wouldn't consider those options for a heartbeat until I hadn't already retained a world-class powder coating consultant to prepare a report tailored to my exact product line. Best of luck.

A. Hello, Atul. E-coating means electrocoating -- sometimes alternately called electropainting, electrophoretic lacquering, CED (cathodic electrodeposition) and so on. The parts are immersed in an electrified tank with a special cationic or anionic paint which deposits on the parts as a result of electrochemical oxidation or reduction analogous to electroplating.

An advantage is full and even coverage -- the deposited paint becomes an insulator, diverting the electrical current to spots where paint hasn't yet deposited). Another advantage is that the coating is quite thin compared to other organic coatings. But that thinness might be a mark against it for durability and corrosion resistance. The two processes can be combined, i.e., electrocoating followed by powder coating.

A. Hi, Praveen. We appended your inquiry to a thread which may offer some general insights. If you provide a couple of paragraphs of additional detail about your components and their application, readers may be able to provide additional info tailored to your particular situation. Some of our readers tell us they will not attempt to answer abstract questions, and they refuse to spend more time/words on an answer than the inquirer spent on their question ... so your 6-word dependent clause won't be a promising start. Please get back to us with a few paragraphs describing your situation. Thanks! :-)

Regards,

A. Hi David.

Anodizing diecast aluminum and following it with powder coating sounds like a good but fairly unusual and (as you mention) expensive finish. I suspect that e-coat PLUS powder coat will be less expensive and more robust. Please remember, however, that pretreatment is a major part of finishing, so it's not just an issue of specifying the final finish, but either specifying the pretreatment or finding competent applicators who supply good pretreatment as a matter of course. Good luck.

Regards,

A. A possible even cheaper process whilst still retaining 10 years protection would be zirconium phosphate followed by architectural polyester powder top coat.

I like Terry's suggestion providing that the geometry of the luminaire is sufficiently simple that full coverage can be guaranteed. An advantage of your present anodizing process, which will be maintained when switching to electrocoating, is complete coverage because both processes are insulative, driving the current to any thin or uncoated area.

Regards,

A. Hi, Gary. We can tell you that all automobiles around the world are e-coated before painting, so that should be some evidence of its value. PPG may have case studies. But I think you will find that most E-coating is not UV resistant, so it must be followed with something. A polyurethane top coat is common, but I think polyester powder coating would be better.

Again, the primary thing that E-coating offers, that painting and powder coating don't, is thinness and 100 percent coverage. Good luck.

Regards,

A. Hi Tom. Yes, the two coatings are compatible, and electrocoating followed by powder coating is a common and very robust system.

Regards,

A. Hi Jeetendra. If the shape of the parts is simple enough that you can be assured of full coverage, with no pinholes or thin spots, and you have a robust pretreatment system like zinc phosphate, I think you should be able to get those hours from powder coating.

Regards,

A. Check the cure schedule of the powdercoater.
Perhaps there is an over-bake issue?
Hope this helps,
Bill

A. Bake your E D coated coated parts at higher temperature than powder coating. This will solve your problem for sure.