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Old 07-28-09, 11:52 AM
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Originally Posted by Falanx View Post
You won't find a waterproof epoxy paint at all, and for two good reasons;

1.) There's no such thing as a waterproof plastic. End of.
Really??? I didn't know that - that's fascinating.

2.) Epoxy system paints were originally developed to be the primer body for high-durability, extreme service applications, such as aerospace and marine, and by peopel who understood and accepted that all polymers no matter their thickness or chemistry allow water and gas transfer. Almost all aeospace calibre paints are epoxy primer based and that primer is not only porous, but the porosity is intentional. Strontium chromate and zinc-potassium chromate bearing films are laid down on top of aluminium, steels, magnesium and titanium alloys to cathodically protect the substrate but they cannot do that without being electically connected to both the substrate and the interface with the next paint layer.
Porosity is a side effect of this? Or is porosity itself the electrical connector, via the flow of ions through it?

The intention here is to put a hopefully, mostly waterproof, ish, barrier coat down on the top of this epoxy and once, eventually water has managed to get through it, then the primer/protection can do its job.
So that would be a zinc(?) primer, epoxy, top coat sandwich???

This said, epoxy undercoat primers are remarkably durable when properly topcoated. I can recommend Indestructible Paints for any of their systems. They sell mostly to industry, but you can deal with them in small quantities as a private purchasor if you don't mind paying for the best.
That's interesting too.

Ok - if someone was painting at home and wanted maximum toughness and ease of use, are there any reasonable options? What about Hammerite? Or Por 15 Hardnose over something like zinc oxide primer? Assuming the Hardnose is UV resistant would the combination be a good one?
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