Undercarriage paint
#5
#7
epoxy needs to be top coated. It has poor resistance to uv and abrasion. Not good for anything that痴 going to be exposed. I would use body color on the underside of the body and a 2k urethane satin black for the chassis.
#8
Why would anyone paint the underside body color?? That's just wrong on many levels...I have several cars with bare SPI black epoxy bottoms and firewalls and all look and perform fantastic. These of course are non UV exposed areas and on cars that are 100% garaged (driven a couple times a year). It is tricky to get the right sheen, it is altered by spray temp, humidity, reducer ratio, number of coats, flash time between coats.... so on this GTO I figured I would step out of my box and try the SEM topcoat over the SPI epoxy. Laid down great and looks super. There are many ways to do this right
#9
Why would anyone paint the underside body color?? That's just wrong on many levels...I have several cars with bare SPI black epoxy bottoms and firewalls and all look and perform fantastic. These of course are non UV exposed areas and on cars that are 100% garaged (driven a couple times a year). It is tricky to get the right sheen, it is altered by spray temp, humidity, reducer ratio, number of coats, flash time between coats.... so on this GTO I figured I would step out of my box and try the SEM topcoat over the SPI epoxy. Laid down great and looks super. There are many ways to do this right
Even the bottom of a car is exposed to uv. It may be much less than the top and therefore the degradation may take a lot longer. However epoxies by nature are very intolerant of uv and should never be used in applications where they are exposed to elements. If you don’t drive it and keep it in the garage, I’m sure anything will hold up fine. The fact that you did it and it hasn’t failed in your circumstances doesn’t make it right. Especially for someone who may use it in different circumstances.
I agree there are many ways to do it right, but exposed epoxy isn’t one of them.
Last edited by ijasond; January 12th, 2023 at 07:26 AM.
#10
I do see that spi adds uv inhibitors to their epoxy. I would assume this is why you haven’t experienced a failure. I’m sure they do this because epoxies are so notoriously prone to uv degradation. Even in a garage uv exposure will kill epoxy, so diy’ers who might have a project, or parts of a project in epoxy for years can use spi with peace of mind. There’s still never a scenario where you will convince me, a professional painter of nearly 3 decades, that any primer is a better topcoat than something like a urethane that is intended to be a topcoat.
I'm not trying to be argumentative. I just can't in good conscience condone a novice seeking advice to be encouraged to leave exposed primer as a finished topcoat on any part of a car. The only exception would be cases of accurate restoration where the factory did it this way. But like I said, they didn't do it because it was ok, they did it to save money at at the expense of the consumer.
I'm not trying to be argumentative. I just can't in good conscience condone a novice seeking advice to be encouraged to leave exposed primer as a finished topcoat on any part of a car. The only exception would be cases of accurate restoration where the factory did it this way. But like I said, they didn't do it because it was ok, they did it to save money at at the expense of the consumer.
Last edited by ijasond; January 12th, 2023 at 07:29 AM.
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May 15th, 2014 07:08 AM