2 questions, first, no matter how much i sand and feather the edge i still "see" the edge when i apply the primer. i go to finer and finer grit till i get to 320, i cannot feel the edge with my fingers before the primer is applied. Next, once the primer is on and dry, you can see where the bondo is under the primer because it drys with a different look to it. its all very smooth just has a different look. how do i fix these problems? thanks Dave

If it is flat and you can't feel the transition with a cotton glove on, then you just need a few more coats of HI BUILD primmer surfacer. You need at least 3 coats over the bondo and the bondo line. Nice wet thick coats. it should look shinny like glass right after you have shot it. Then wet block it with 400 and if you aren't using sealer I hit it with 600 on the wet block as well to make sure they aren't any scratches. remember to guide coat before you ever get the wet sanding stuff out and let it dry. Wet sanding primmer / surfacer with no guidecoat is like driving blind! :D

sheetmetal, what you are seeing is nothing to be worried about IMO. The filler will absorb some of the solvents while the adjacent primer, metal, or old finish does not. These different rates of solvent release will cause the primer to look different from one substrate to the next. Very similar to what is called a bullseye in a paintjob. I'd bet the second time priming these areas if no filler is showing the primer will be all one shade.

Am with bob on this one, many times its just how the primer gets "absorbed" Have a problem like this on dodge products especially minivans. No matter how well you feather edge out the paint you can see a repair ring. But once you block it out and paint its GONE.

You should do all your primer blocking IMO with 180 up til that last coat or round of primer. Anything more then 180 is just kinda polishing the surface and NOT cutting it level...Eric

Bob is right on the money, that is the reason you are priming it right? You don't paint right over the plastic filler repairs because you are seeing exactly what will happen. You apply the primer and "surface" it by sanding, or blocking (same as sanding really, but with the sand paper on a block).

Originally posted by zachscc:
Nice wet thick coats. it should look shinny like glass right after you have shot it. Zach, You will really get yourself into trouble with that procedure. Atomization is VERY important, even MORE important in primer than in top coats. If you pile on primer, it WILL shrink later. I don't care what brand, it WILL shrink (ok polyester primer "May" not, but urethane sure will. CLICK HERE for the "Basics of Basics" on gun set up and atomization. (http://www.camaros.net/forum/ultimatebb.php?ubb=get_topic;f=3;t=002548) In it you will see an example of exactly what we are talking about here. Properly atomized primer will actually fill MORE than that bombed on way.