Hi all,
I have a rather odd problem.
The attached pic shows the story.
The paint on the steel "weathers" very fast compared to the paint on the poly nose cone.
They were painted at the same time outta the same gun.
Whats up with the difference?
Anybody know?

Maybe the nose was painted later or if a single stage was used, they might have used more gloss hardener.

Is it clearcoat? My truck is not clearcoat and it fades really fast.. Just wax it and it should shine up. I don't know why it does that on metal and not other parts.

I'm not exactly sure why it does that either. Maybe because the metal heats up more from the sun, and holds the heat longer than plastic? Just a thought.

That is kinda weird why its like that. I thought about the whole metal vs. fiberglass thing too, but that hasn't happened on my truck where I know I put some filler. Have you always owned the car? The paint looks like the same color, but the paint on the nose looks like base/clear while the other paint looks like single stage. Mystery??

No guys......out of the same gun at the same time.
Same paint and everything.
Non basecoat/clearcoat. Just single stage enamel on both surfaces.
I can wax the crap out of the metal part and it fades real fast.
I have never waxed the poly part at all.
The metal has been waxed countless times.

Strange isn't it?
The car sits in shade most of the day so I don't think it is the sun.
I know it is oxygen reacting with the paint.
The poly part moves around a lot more due to heat expansion and I would think that would make the poly paint go faster 'cause it would crack the paint whenever the substrate moved.
I don't know....

ttt

My Toyota did that for while.... when I repainted using some cheap one stage, the metal would apear duller then the plastic bumpers. I think it has to do with temp. when you paint it... the plastic has a higher heat capacity, but a lower heat transfer then the metal., so it's gonna be hotter ( or cooler) then plastic

Okay, let me first say I don't know ANYTHING about painting.

But, just considering the different properties of the materials, is is possible that the plastic was less porous, so more of the finish remained to make a very smooth surface? Perhaps the finish on the metal is microscopically rougher, so that a little bit of weathering is all that it takes to change the reflectiveness?

Talking out my B*tt here, but there you go.

Brian

Brian, you are not off base really, I think you are on to something. Not that the plasic is so different, I am thinking what primer was used and was it different from one part to the other? It is something to do with when it was sprayed as opposed to now. The metal being colder kept solvents from flashing off and the paints durability suffered. It retained the solvents initially, the top surface cured or simply "dried". Then the solvents broke down the paint.

Another example of the effects of the solvent sandwich....

With Primer's post it occured to me that it is probably the fact that the poly absorbed some of the solvent and let the paint cure more slowy giving a smoother surface. This would give the paint less surface area to react with oxygen molecules.

Thanks for the replys Guys!!