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sanding swirls under my fresh base coat...what to do? #1312536
09/29/12 05:59 PM
09/29/12 05:59 PM
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Vicksburg, MI
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coffeeman383 Offline OP
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I tried to rush a paint job today and skipped high build primer and sanding. Applied 3 coats of shopline BP basecoat and I can see blotches from small repairs and many sanding swirls. I'm assuming clearing it now would compound my mistake. Can I spray a high build primer directly over the basecoat? Or do I need a sealer first (or something)? Or should I keep building the basecoat?

Can I then apply base directly over the high build primer? The shopline spec sheet says I can but the shopline brochure recommends a sealer first. The car is just a driver (with $100 of wasted paint on it

Re: sanding swirls under my fresh base coat...what to do? [Re: coffeeman383] #1312537
09/29/12 06:58 PM
09/29/12 06:58 PM
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Amherst,NY
challengermike Offline
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i would scuff it with a red scotchbrite pad before you prime over it. You can spray paint over the primer without sealer, but they tell you to use sealer so it bonds better and it may also fill slight inperfections.

Re: sanding swirls under my fresh base coat...what to do? [Re: challengermike] #1312538
09/29/12 07:34 PM
09/29/12 07:34 PM
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Columbus, Ohio
Chally426 Offline
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Prime and seal, or your likely to see them again

Last edited by Chally426; 09/29/12 07:35 PM.
Re: sanding swirls under my fresh base coat...what to do? [Re: Chally426] #1312539
09/30/12 12:56 AM
09/30/12 12:56 AM
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Kalispell Mt.
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HotRodDave Offline
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I am having a similar issue, I was gonna just wet sand the red with 1000 grit then spray another coat. Is that a big no-no? I already wet sanded the hood and looks like all the scratches came out


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Re: sanding swirls under my fresh base coat...what to do? [Re: HotRodDave] #1312540
09/30/12 01:15 AM
09/30/12 01:15 AM
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Lakewood, Colorado
herkamer Offline
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You can apply a primer over a properly prepped surface, even if it's fresh. I wouldn't seal before you prime in this case. Definitely check and see what the primer manufacturer says for what grit it should be sanded with prior to actual application.

Also, 1000 grit is way to fine for reapplying color. You will likely have delamination in huge sheets. 400-600 is as fine as I ever go unless I'm color sanding and buffing.


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Re: sanding swirls under my fresh base coat...what to do? [Re: coffeeman383] #1312541
09/30/12 06:26 PM
09/30/12 06:26 PM
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Vicksburg, MI
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coffeeman383 Offline OP
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Nope, scuffing with a red pad and applying a high build primer was a bad idea. No bite and/or just incompatible. The primer is cracking like a drying mud puddle and is able to be scratched off with finger nail. Data sheet for the primer says 220 grit, doh!

Monday I'll start to sand off the primer and get back to the base coat with 220 grit. Still not sure what to do, will try to get ahold of a PPG rep.

So, what would bite best on fresh basecoat?

Re: sanding swirls under my fresh base coat...what to do? [Re: coffeeman383] #1312542
09/30/12 08:08 PM
09/30/12 08:08 PM
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Spokane Washington
ScottSmith_Harms Offline
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Sounds like you need to strip (it all) off and start over to do it right?

Re: sanding swirls under my fresh base coat...what to do? [Re: ScottSmith_Harms] #1312543
09/30/12 08:49 PM
09/30/12 08:49 PM
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Cincinnati, Ohio
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Quote:

Sounds like you need to strip (it all) off and start over to do it right?




This is the best way.

You pretty much have to anyway to reapply the fill primer to get the sanding scratches out. They will keep coming back no matter how many coats of fill primer you put on top. So I would
sand it all off and do it right. Why in the world would skip sanding and a sealer?

Re: sanding swirls under my fresh base coat...what to do? [Re: Challenger 1] #1312544
09/30/12 10:42 PM
09/30/12 10:42 PM
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Amherst,NY
challengermike Offline
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i would say they were incompatible. Im pretty sure the red scuff pad is equal to 220 grit. when you can just scrape it off like it didnt cure its a compatablity issue. I had that happen 1 time when i used ppg base and put sherwin williams clear over it. The clear wouldnt cure.

Last edited by challengermike; 09/30/12 10:46 PM.
Re: sanding swirls under my fresh base coat...what to do? [Re: HotRodDave] #1312545
10/01/12 12:15 AM
10/01/12 12:15 AM
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Jacksonville Florida
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Quote:

I am having a similar issue, I was gonna just wet sand the red with 1000 grit then spray another coat. Is that a big no-no? I already wet sanded the hood and looks like all the scratches came out




As long as you are in basecoat stage and no clear has been applied and scratches are very shallow like from 180-220, you should be OK. Just keep in mind that these scratches might show a little in the gloss.They can be buffed out after clear has cured and hardened up. Do not try to do this with 80 grit scratches







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