Hi,

New guy here. First I'd like to open by saying thanks to everyone on here for the depth of posts and info. I've been lurking/searching for a while as I've worked on my home resto and the advice here has been very helpful.

However the time has come to ask some specific stuff, so here's the rundown:

Car is a '68 Nova. I used the PPG stuff (mostly Deltron) to paint it last fall- DP90, VP2100, K38, DBC, 2021 clear and at first glance it came out great. It's a dark grey metallic and there were no issues with tiger striping or anything like that.

But I was inspecting it a few weeks later and I noticed that from a particular angle from the rear I could see waves in the rear quarter panels, and I later confirmed that some spots were poorly block sanded.

So this month I finally had time to start the repair. I blocked the quarters with 180 and then 220 to see how it would level and while some of the very shallow waves came out there were still a few that were noticeable.

Out came the K38 and I shot and blocked the quarters until they were smooth as glass, doing a bunch of wet checks to make sure I'm good. Since both quarters need new base/clear I figured I'd try to minimize blend lines and do the roof as well. As I was sanding it down I cut through the clear in to the base in a few spots.

The car as it sits right now is as follows:

Both rear quarters are blocked FLAT this time and are in K38, 600 grit
The roof was sanded with 600 grit and has a few burn throughs into the dark grey base. The rest is sanded 2021 clear.


So my questions are this:

1.) I know that spraying new base over burn throughs can cause wrinkling/lifting due to the new base reacting with the old. When I sprayed the original base it was the 1:1 DBC and DT870 blend. Can I just prep the sand throughs with, say, 320 and hit them with some surfacer (and then level it) to get them ready for new base?

2.) My quarters are in K38 and the roof and blend areas are in sanded 2021 clear. Assuming I can shoot K38 over the sand throughs this will leave some areas in the roof in dark grey base and sanded clear and others in light grey K38. When I first sprayed the base last fall the coverage was excellent and consistent even after just the first coat. However I'm a bit concerned about having two different color substrates like this. Part of me thinks that I'll be fine rebasing as-is, however now I'm wondering if I should reduce some of my leftover DP90LF and spray it as a sealer. I know that some people use sealers while others do not, and I'd just like some advice on when it's necessary. I'd like to avoid adding more film thickness and steps to the process if it's not a big deal.

Oh, and if I use a sealer then the new dark grey metallic DBC will be going over black DP90LF while the parts of the car that are not being resprayed will be the existing dark grey metallic DBC which was sprayed over light grey K38. I'm concerned that their may be a color mismatch then.

All help is much appreciated!

Thanks!!

just spot prime the sand throughs with a 2 part primer, your dp or k38 should work. now you say your ready to spray the quarters. ARE you going to blend into the doors, if not your going to need to. also are you going to spray the trunk lid, you'll need to do that also. you might go over the sanding with some 800. I wouldn't use a sealer, but its not prohibited
Jay D.

badsix wrote:just spot prime the sand throughs with a 2 part primer, your dp or k38 should work. now you say your ready to spray the quarters. ARE you going to blend into the doors, if not your going to need to. also are you going to spray the trunk lid, you'll need to do that also. you might go over the sanding with some 800. I wouldn't use a sealer, but its not prohibited
Jay D.

Thanks Jay!

I actually got some time over the weekend to take a crack at it. I blended in to the adjacent panels and that seemed to work out well. Also, I had no issues with any of the old base lifting, all that seemed to go smooth.

But:

When I spot-shot the K38 over the sand throughs I let the primer cure for a few days. Then I came back and leveled it out with 600 grit to where the edges were soft and well feathered. I don't think I could have sanded it much further without going too thin on the primer.

When I shot the first coat of base I noticed that I was getting bleed through/telegraphing of the primer (I think bleed thorugh is the right terminology). Basically you can see the patches where primer was sprayed through the base coat. So I held off spraying a full second coat, let it dry a bit, and then went back to some of the spots and hit them with more base. It appeared to help a lot, but if they are still visible what can I do moving forward? I am assuming that the issue is because the K38 and sanded clear are absorbing the base differently? Or am I just expecting too much from the first coat of DBC?

I figure everything will need to be hit with 600 and re-shot with something, but I'm unsure if this is the type of thing that gets covered with more surfacer, sealer, or did I actually just spray DBC as a really expensive sealer and I can just go right back to basing after sanding?