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Paint tech - primer sand through

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Old Sep 30, 2005 | 09:50 PM
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Default Paint tech - primer sand through

I've been working hard all week to get my '77 to the point of shooting paint this weekend. I just finished wet sanding the PPG K36 final primer layer this evening and I have a few, maybe 8-10, spots where the primer was a little thin and I sanded through to fiber glass. Do I need to re-prime these spots and wet sand them one more time?
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Old Sep 30, 2005 | 09:57 PM
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Yes!
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Old Sep 30, 2005 | 09:58 PM
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Are you putting sealer on top of the primer? If you are then it should be fine.

If you are shooting paint on then you better touch up those spots and lightly wet sand them again. Main issue will be why you broke through. Is it high there? Do you need to feather in that area? Hard to know from here.

Good luck with it. You already know the preapration is 90% of a great paint job.
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Old Sep 30, 2005 | 09:59 PM
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I was afraid that was the answer but with this much effort into it (about 40 hours on just the body!) I want the job to be RIGHT!
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Old Sep 30, 2005 | 10:03 PM
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Originally Posted by stingry
Are you putting sealer on top of the primer? If you are then it should be fine.

If you are shooting paint on then you better touch up those spots and lightly wet sand them again. Main issue will be why you broke through. Is it high there? Do you need to feather in that area? Hard to know from here.

Good luck with it. You already know the preapration is 90% of a great paint job.
You can seal over the K36? I put down the sealer, PPG DP-40LF, as the first stage.

The places where I got sand through were mostly the usual suspect areas of edges where I got a little too aggressive. By the end of the sanding I about had the tecnique mastered to avoid doing that but in the mean time I've got the "starter" issues to deal with.

Last edited by steves_77vette; Sep 30, 2005 at 10:05 PM.
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Old Sep 30, 2005 | 11:03 PM
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If it aint right before paint it wont be any better after paint.
In fact, it'll be worse.
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Old Oct 1, 2005 | 10:07 AM
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Sounds like your not using a guide coat. This really helps in showing where to sand and where to stop. Can be used on all layers put down.
Either a contrasting color of lacquer don't use enamal it plugs the sand paper or there is a powder with an applicator pad. I think its nothing more than copier back stuff- graphite.

Just a mist coat is needed.
Another tip is leave all the peaks in the area for last. Its easier to go flattish method and the patient edge method seperately.
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Old Oct 1, 2005 | 07:55 PM
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Nope, did a guide coat. The corners and edges are just naturally thinner as well as easier to get too agressive with them.
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I don't use sand paper for the last sanding. I use scuff pads. They will not cut through the primer. They just scuff up the primer so the paint will stick. That works for me
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Old Oct 2, 2005 | 09:17 AM
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Originally Posted by steves_77vette
You can seal over the K36? I put down the sealer, PPG DP-40LF, as the first stage.

The places where I got sand through were mostly the usual suspect areas of edges where I got a little too aggressive. By the end of the sanding I about had the tecnique mastered to avoid doing that but in the mean time I've got the "starter" issues to deal with.
I just did my DD and we primed it all then sealed it after primer. I did this so that nothing underneath would bleed through to the topcoat. Thats what the local auto paint store told me to to. It was completely opposite what I thought the order was but it turned out great for me. I did use DURON as top coat though. My primer and sealer were PPG but cannot remember the numbers.

We shot the sealer and then painted the topcoat within an hour of doing the sealer.
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