sanding scratches showing through - use filler primer?

Well, I've been tinkering on a spare KNE Guitars body off & on the past couple months and ran into a small problem yesterday.

I sprayed it with Deft Sanding Sealer about a month ago, waited a good week and sanded it down smooth. I went to spray primer on it yesterday (Duplicolor Sandable Primer) and topped it off with stock Duplicolor White Acrylic Lacquer and afterwards noticed that there are some sanding scratches in the body, most likely from the factory that I apparently never got out.

For some reason, these didn't show up when I sanded down the S&S (or I was lazy & missed it), and were only mildly apparent when I sprayed on the primer.

Now that the color coat is on, they're pretty obvious when the light hits the body. Luckily, it's only on the front & back; the sides are fine.

I plan on sanding the front & back down with 220 and then use some Duplicolor filler primer (2 coats, sanding in between coats) to make sure it's even.

Would I need to sand the front & back down to bare wood, or could I sand the color coat just enough for some filler primer to stick?

If they are just light scratches in the color coat try something not as rough as 220. It's hard to say without pictures but you may be able to smooth it out with like 600 to 800 grit & then shoot a couple more coats of color & move on. I wouldn't go back to bare wood unless they are really terrible... Pics would help though.

Good point. 220 is fine enough for bare wood before you start finishing, but its way to coarse for cutting back or leveling between coats of finish. There you'd be in the range of 600 or so, give or take. So it might just be scratches from the primer that are printing through.

I used 320 the other night to knock it down, then sprayed the first new coat of primer. Just regular sandable primer since I couldn't find the filler primer in white.

I waited a day, sanded with 320, and hit it w/ the 2nd primer coat. Seems to be working. I haven't sanded the 2nd coat of primer, and only hints of the lines are showing through now. I figure another sand & coat of primer should do it. I definitely won't do color coat until the primer coat looks perfect. If it doesn't look right after sanding this 2nd coat, I may just sand the whole damn thing back, or use some acetone to make it easier.

Another weird thing, on the edge of the body where the forearm contour meets the edge (near the bottom strap button), I can see the grain telegraphing through, like the prior paint coat sunk into it a bit. Weird, since I used sanding sealer at the beginning.

I think the issue is that I didn't take a damp cloth to the body to raise the grain and knock it down prior to putting on that first coat of sanding sealer. So when I thought I smoothed the S&S down, it really wasn't and now I'm seeing all these imperfections come through.

So if anyone tells you that you can start w/ bare wood and hit it w/ sanding sealer--- say NO! You NEED to wipe it down w/ a damp cloth first to raise the grain, then sand it back down--- do this twice.

Uggh! it's never easy, is it?