Woody,
I think you need to try it out. I can't explain why but I can tell
you that it will happen and I've been doing this for 35 years.
The last time it showed up was when I filled the small seam between a rear fender and the rear corner piece for a smoother look
down the side of my PU truck I was customizing.
Maybe it took more than a year, time seems to slip bye, but the point is that it did take place. I've still got that truck and could show it to you. It's not a lot of shrinkage,but at the right angle you can see where that seam is. No lie, Just fact.
I think it is the very reason pros like Coddington will use lead
to fill a deep area then top it off using plastic. Otherwise why
not use plastic for the whole job.
I just thought I'd mention this so someone doesn't get disappointed with the outcome in a few years.
Dan
