Has anybody here had problems with ghost lines in thier paint? The roof is black and i was contemplating going with a lighter color. Any opinions on if this will not make the line so obvious.

wade

 

Ghost lines from what? A previous repair? Need more info....
Yes, black or dark colors will show every little imperfection...

 

I did a chop top on it and where we welded it back together i have a small place that shows back up in the heat.

 

It's hard to say what the root cause is without knowing more about how you did the repair and finish work, primarily the types of fillers/ primers, etc., were used, and what kind of thickness you may have. I can tell you that fiberglass is notorious for having these kinds of things come back in the heat, especially with dark colors. I haven't seen it so much with steel, but if you have an overabundance of filler, or you used a lot of primer-surfacer, or didn't get the mix ratio right, or any number of a thousand other little things like that, stuff can move, expand and/or contract with temperature changes.

Dark colors certainly will show more than light, so a repaint in a lighter shade would be beneficial. Not only for a showing standpoint, but also a temperature one, as well. If the metal stays cooler, reflecting the heat instead of absorbing it, the undersurface won't shift and move as much, either.

 

Was it butt welded or lap jointed at the seam? Reason I ask is this sounds exactly like a lap joint, where you have one thickness of metal on one side of the joint, two on the other. There will be different expansion rates between the two, and they will typically show a ghost line when exposed to heat (sitting in the sun at a show).

 

I butt welded the two together ground that down and then put long hair fiberglass and after that filler. Its not that bad but i think a color change will be in my future.

thanks

 

Fiberglass and steel also have different expansion rates, so I guess it's possible that could be causing the issue. Do the ghost lines show up at the outer edges of where the fiberglass stopped?

 

That also happens where the panel developed a pillow or oil can from welding shrinkage. The builder thinks well that's ok, it's low I'll just fill it. Then when they take it out in the sun the metal expands and the oilcan pops up pushing the filler above the desired level and showing the edge. if you sand it down, then when it cools off it pops back in again, showing up the other way. It's a difficult problem to fix I've seen pros get frustrated and brace the roof from the underside with bows packed with felt or even spray foam. (DON'T use spray foam! It keeps expanding when heated and can even blow a weld apart.)