Do I need to prime over sanded fiberglass?

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PostPosted: Thu Jun 20, 2019 7:00 am
Hi all,
This question was my first post but never showed on the forum so I'm asking again.
I am repainting the area above the windshield on my motor coach due to peeling clear coat.

I sanded off all the clear coat with 120 grit, followed by 220 and feathered with 600 grit. Some of the base coat sanded off to expose the gel coat.
I'm painting with 3-M Diamont. Base coat is the same color (brown) followed by the clear.

Do I need to lay down a coat of primer-sealer? Or can I spray my base coat directly on the fiberglass surface I have now?

I do have a can of Eastwood 2K Aerospray Urethane primer I could use. But it's a rattle can and I'm not sure I will get a good even coat with it - so it may be better to not use this on such a large surface. I don't mind buying 3-M DP20K urethane primer if necessary, but that would cost me another $200 and of course I don't want to waste my money if I don't have to.

Thanks
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Coach repainting-repairing peeling clear coat on Beaver motorcoach

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PostPosted: Thu Jun 20, 2019 9:08 am
https://www.autobody101.com/forums/viewtopic.php?f=13&t=27546&p=205226#p205226

Maybe one of the Mods can merge these threads?

Since we now have a picture, it looks to me like you have a bit more prep to do before primer. Those edges don't look particularly well feathered to me.

Since you've changed your mind on buying primer then that is the better way to go, compared to using the rattle can.
Chris



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PostPosted: Thu Jun 20, 2019 9:43 am
Thank you for replying Chris. I did not realize my original post was in the Fiberglass section - I was looking for a reply here, in the "Body & Paint" section, which I why I thought it did not post.

It was stated in the other thread, that I do need to prime.
So I will order the BASF/3-M DP20 2K Urethane Primer-Surfacer.

Thanks



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PostPosted: Thu Jun 20, 2019 9:52 am
NFT5 wrote:Since we now have a picture, it looks to me like you have a bit more prep to do before primer. Those edges don't look particularly well feathered to me.


I can't feel an edge running my fingers over it. Feels smooth.
How should I test (what do I look for) to know the sanding is complete?
What grit should I end with (600?) before spraying the primer on?

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