Sanding directly before basecoat

T

Tiggie

Here is what I have so far:
Bare metal sanded with 80 grit
2 coats of epoxy, dry 24 hours
Filler where needed after the 24 hours, but within 7 days.
More than a week past, sand filler, some block sanding and 180 with the DA since more than a week past.
2 more coats epoxy.
2–3 coats of regular build primer.

Following the advice here, at this point I’d be looking at a final block out and scuff of the regular build, and then seal with reduced epoxy and spray the base. But...

I am a novice and will be painting in my garage. Dirt and imperfections in spray technique are bound to happen, and only multiply with multiple coats.

Can I follow the tech sheet of the regular build that says I don’t need a sealer? Everything there would be sanded at probably 500-grit. What kind of time window, if any, do I have with this method? . This will fix my dry areas, runs, and/or dirt.

If I can’t do that, can I put unreduced epoxy over everything and do my final block out and scuff before basecoat the next day (or two or seven?). Or does sanding the epoxy kill the 7-day window?
 
Sounds like you are doing a "perfect" paint job! I really like the epoxy as a sealer myself, but have painted many cars over sanded primer over the years without problems. The advantage of using the epoxy as a sealer is it really is a sealer, and will not let the solvent penetrate like 2K will. You could put an unreduced coat on and scuff before base like you asked, or just shoot a reduced coat on before base, and if there is trash in the base, let it dry a couple hours to overnight, scuff the base, put on 2 more coats, then clear.
 
Thanks texasking. Certainly trying to get the most “perfect” job I can do given my equipment and setup.

Right now I am leaning towards doing the biggest part of the car in unreduced epoxy, 24ish hours to cure, final scuff, clean, and let the base fly.

Smaller parts I may go reduced epoxy since I can do them quicker and not worry about the epoxy window closing.
 
Be sure to use guide coat when block sanding and final sanding.
I encourage the reduced epoxy sealer coat because it will reveal any imperfections you may have missed. If something is wrong it's generally an easy fix and for that matter the entire sealer coat can be wet sanded with 600 if necessary to ensure a great foundation for your base coat.
 
I just question the regular build after the filler and more epoxy. Do you need more body work? More filler?
If you need more body work after you put that on or are just sanding that back down to the epoxy using that as your guide coat? I would say if you end up with mismatched primers, like gone thu to expoxy, or used some glazing of that last coat, I think that is what makes the decision for you of whether or not to spray another sealer. That sealer is what keeps the paint from reacting different over poly, filler or epoxy. That is the cheapest insurance you can buy. There are some regular builds that you can mix as a sealer too, just seems like epoxy is the lock down for anything creeping thru.
 
anotheridiot said:
I just question the regular build after the filler and more epoxy. Do you need more body work? More filler?.
Click to expand...
The regular build 2K when down after the filler and epoxy to give me a little more room to fill imperfections, if needed. The car is pretty slick at this point because I took forever with the filler work. Plan is to guide coat and block and see what happens. But the car looked generally okay in black epoxy before the 2K went down.

In my teenaged years, I didn’t understand the importance of blocking and wow the sides of that car looked like ocean waves. So now I’m being extra cautious. That job was cheap lacquer primer over direct metal and a single stage urethane on top. 12 years later, it’s still okay other than the wavy sides and some fading on the top sides.
 
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