[72c20customcamper]

Originally Posted by lupo

Let's get some facts first. I have been involved moisture cured urethanes for over 30 years. Clear moisture cured urethane is used as a sealer for concrete floors. When you add black pigment you have black concrete sealer. When Mobay chemical developed Bridge primer the only color it was available then was silver. Engineers at Mobay figured out if they could cut off moisture and oxygen you could not create rust. And if it was applied in layers over the rust the rust could not continue. Resin which is moisture activated it's completely waterproof I will suck the water right out of the substrate. By adding aluminum flake or matacious iron oxide was used to cut off the oxygen. When I asked their tech department about the black thier response was' it's silver like it or lump it;! So when you open up a can of black moisture cure urethane and paint your chassis this is not the way the system was designed. the name of this system is called Three Coat Polyurethane System consists of two coats of aluminum pigmented silver primer And a color coat. To manufacture this primer the humidity cannot be above 60% or you will wind up with Jello a week later. To give you a comparison the Three coat polyurethane system will do 14000 hours of salt fog testing Zinc phosphate epoxy primer will to do around 700 hours. Industrial Zinc-rich primer epoxy 3000 hours. There are new epoxies coming out of Europe that utilize Zinc power and glass spheres or Mica flakes that cut off the oxygen to improve corrosion performance I cannot believe how many auto restoration supply companies ,in the last 30 years, sell black moisture cured as a permanent rust sealer.

Reason I use it isit takes much more abuse than regular paint . I rarely put it on rusted metal mostly sandblasted steel . Overkill ? Probably ,good old rustoleum would probably last just as long specially because I dont drive in snow salt roads with my old vehicles. My lark I blasted the frame epoxy prime and PPG DCC and it still looks new after 22 years