First off, this is my first post. figure i should say thanks to all of you since i have been learning so many new things from this site that have made my life a little easier. I am a collision painter. I do all of my own personal bodywork and i have been doing it for a few years. this problem has been bothering me lately though. I am having this issue where all of my patch panels have been welded in on my car. I did the bodywork last winter, sprayed it right after and i noticed the ghost spots once it sat in the sun for a couple days. a block and buff will hide them for a month or so but then they faintly re appear over time. my process was the following:
1) cut filler panels to exact size, same gauge sheet metal as factory panel. stripped paint back ~4" around are to be welded
2) butt welded in place. about 5 tacks spread apart, let panel air cool, then 5 more in between previous, etc. once it looked solid i ground down the welds, used my hand sand blaster gun to clean out the small gaps between the welds, then welded the remaining gaps up. (miller 180 w/ gas)
3) ground down the remaining welds
4) I have done both of these processes on 2 different patch locations on the car. First was a coat of duraglass filler, rage gold, icing. then the other was just rage gold, icing. both areas have the same ghost effect. after i block out each filler i tend to let it sit for an hour or so to make sure its had some time to cure before skimming on the next. all done in 70-80 degree shop temp.
anyone have any ideas what my problem might be? i figured it would be filler shrinking into gaps between welds because thats what the ghost image looks similar to, but i make sure to leave no gaps before filler. nobody else has noticed it but its one of those things that pisses you off to no end. i spent a ton of time blocking, priming, letting everything shrink, flow coating, buffing to get a super straight/super smooth panel then to have a ghost line appear where my welds are
I am currently in the process of respraying the car a different color and it got to the point where i stripped the doors down just to make sure all of the prior metal work looked proper since i have learned much more about metal work over the last year than i did when i started working on this car last winter