How fine of a grit can 2k Primer surfacer be sprayed on?

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PostPosted: Thu Oct 18, 2018 8:47 am
Hi there!

Onto a new project, all coming along nicely. Me being me, I start stressing about things that haven’t occurred yet but I anticipate an issue down the road. Anyway my question is, will 2k surfacer successfully adhere to 600 grit primer?

I final sanded my roof (600 grit), and cut through to a small patch of bare metal, and decided to spot prime a couple of coats of my surfacer over the general area. I could of used my primer as a wet on wet surfacer and continue with base but I decided to let it dry and reblock it with 320, then 600. I thought this would be safer for my skill level as I wouldn’t run the risk of a high spot because of extra material or any unessesary texture.

I kept away from the masking but I did get a bit of a paint edge that the 320 took care of.

So now the primer is blocked and feathered, I can’t feel an edge or see any wobbling when I’m wet checking, but the feather edge looks weird to me, it looks “tight” and not a long gradual feather edge like other panels.

Someone please tell me i’m going to be okay!! Hahaha otherwise I’ll long board the roof with 320 dry and reapply primer and final sand again!

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Cheers

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PostPosted: Thu Oct 18, 2018 9:13 am
Try shooting a reduced coat of 2k primer as a sealer coat over that panel. If you can still see it after that then you need to shoot some more and re-block.

The unwritten rule of thumb is to wet sand with 400 for solid colors and 600 for metallics. Any finer grit than that you risk adhesion problems.
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PostPosted: Thu Oct 18, 2018 9:58 am
To truly level a spot you need to sand it first with a grit more
coarse than 320. You need a guide coat to see it.
I very often sand my primer over body work with 180 first,
then re-guide coat and sand it again with the finer grits.
If it looks unlevel in primer it will really look unlevel in paint.
JC.

(It's not custom painting-it's custom sanding)



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PostPosted: Thu Oct 18, 2018 11:30 am
:goodpost:
Jay D.
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PostPosted: Thu Oct 18, 2018 4:51 pm
So I’ll get no issues with applying that primer over 600 grit? The roof is blocked and flat, it’s just the spot prime I’m querying. Thanks

Edit: and the different colour of primers is the same stuff, the darker is when it was mixed up in hi fill mode

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PostPosted: Fri Oct 19, 2018 7:29 am
UCANG wrote:So I’ll get no issues with applying that primer over 600 grit?


No problem at all.
Primer will adhere to much finer grit with no problems.
Body shops spray primer all the time where it extends into blend
areas that may have only been scuffed with gray scotchbrite pads
and that's like 1500 grit. Never an issue.
Being clean is more important than grit size.
JC.

(It's not custom painting-it's custom sanding)



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PostPosted: Fri Oct 19, 2018 7:47 am
Thanks! Thats great to hear. Yes rather than repriming and blocking the whole roof for one small cut through (after I finish sanded 600 ready for top coat), i put a couple coats of 2k over the general area and blended it out. I didn't put a harsher grit over the area that I spot primed and started to stress out. At least I won't have much shrinking issues with a 600 grit! :D

Anyway its all blocked and looks great with no transition to be felt. Even wet checking and sighting the panel yielded a nice result.

Top coat to follow in the upcoming weeks. Just have to first clean my DIY booth, inspect, mask, inspect, clean, clean, inspect, clean.

Cheers

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