Question about sanding

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PostPosted: Wed May 20, 2020 3:40 pm
I primed my bumper with two light coats of epoxy primer with activator. I let it sit for 24 hours and I started sanding it with 220 by hand with a small 4-in block.

As Im sanding The primer started coming off easy so it's kind of like a guide coat. There's a few low spots but I'm not 100% sure they are low spots because I don't feel them. Little confused as I'm not sure if the primer is on there better in that certain spot or it's a low spot and I should keep sanding. Here's a pic of it Tell me what you think
https://photos.app.goo.gl/r7Yz9hJ9HeQG3FnXA

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PostPosted: Wed May 20, 2020 4:07 pm
Epoxy is not designed for use as a build primer and two very light coats will certainly be too thin to take sanding with P220.

If you need a primer to be sanded to achieve the finish required for base then use a proper high build primer. If you're using the epoxy as a sealer then it should not need sanding for mechanical adhesion - just denib if necessary and proceed with base.
Chris



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PostPosted: Wed May 20, 2020 5:28 pm
NFT5 wrote:Epoxy is not designed for use as a build primer and two very light coats will certainly be too thin to take sanding with P220.

If you need a primer to be sanded to achieve the finish required for base then use a proper high build primer. If you're using the epoxy as a sealer then it should not need sanding for mechanical adhesion - just denib if necessary and proceed with base.


Yes i learned epoxy is not made for sanding. Well since this is all i have, and the tech sheet says its sandable, I already see where I have to fill in and it looks like I don't have any low spots but I have some small scratches, is it possible that I can use glaze putty right on top of the plastic, sand it down to a paint ready finish, reprime with epoxy and proceed with the painting. The most important thing I'm worried about is adhesion, That's why I went with epoxy because it has really good adhesion. I had someone paint my bumper previously That's why I'm doing all this and the paint was chipping all the way down to primer and a lot of areas

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PostPosted: Wed May 20, 2020 10:49 pm
Yes, you can use filler over epoxy, sand back and re-cover with epoxy before your top coats.
Chris

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