Preparation with new EDP coated panels?

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PostPosted: Tue Mar 20, 2018 2:01 pm
Hi, I'm fairly new to the auto paint world but I'm undergoing a personal project to replace the hood and driver-side panel on my 2005 Audi A4. I've done a considerable amount of research on prepping but there's not a lot of info specifically for new panels as most are regarding restoration. Due to that, I feel I might be overthinking a lot so I'm hoping someone can help clear it up for me.

I just purchased and received new aftermarket panels (Hood and Fender) and they both state on the website that they are EDP coated. In that case, is it safe to go ahead and wetsand 320 grit, clean and apply primer sealer before heading onto the painting stages?

Thanks for any help!



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PostPosted: Tue Mar 20, 2018 4:25 pm
Yes, I wet sand the new panels in 400, then epoxy and paint.

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PostPosted: Tue Mar 20, 2018 6:20 pm
I would first read the tech sheet of the product you plan to apply to see what the manufacturer recommends for their product. For example: I use Matrix Epoxy and their tech sheet says to scuff thoroughly EDP coated panels with a 3M 7447 Scotchbrite pad and then apply epoxy primer.

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PostPosted: Tue Mar 20, 2018 9:39 pm
Make sure it's a true EDP by wiping the new part with a rag dampened with enamel reducer. If the primer comes off on the rag, you need to remove it all. If the rag stays clean you're OK.

Many overseas aftermarket mfgs simply coat the parts with lacquer primer to prevent flash rusting in transit and call it EDP...
"If you can't move it, paint it." - U.S. Army



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PostPosted: Tue Mar 20, 2018 10:40 pm
all good advice ^^^ I think he meant wipe with lacquer thinner, if its a lacquer base material the lacquer thinner will remove it.
Jay D.
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PostPosted: Wed Mar 21, 2018 1:57 pm
First of all, thank you guys for responding so quickly!

I do know about the testing step to be sure it's legit EDP, I would imagine it is, the website I purchased it from seems very reputable but I definitely plan on testing it beforehand.

Someone once told me wetsand 320 grit over it, so suggesting the 400 grit instead, is that to be safer on not sanding off the EDP?

And two of you mentioned EPOXY primer, I was under the understanding that if it was a true coat of EDP that I wouldn't need to apply more primer, just primer sealant to help seal and color hide.

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PostPosted: Thu Mar 22, 2018 1:50 pm
Again, first thing is to determine what brand / product line you intend to use and then follow the steps as recommended by the manufacture. In my case, I use Matrix and this is how I would do the repair using their products:

1st) I would test fit the panels to make sure they fit correctly and then modify them as needed. More than likely the aftermarket panels will not be perfect bolt-ons out of the box and may have flaws, scratches, subtle dents, and imperfections. If you paint over these as is, they will be magnified.

2nd) I would follow the paint manufacture's process. In my example using Matrix, I would scuff the panel to create a mechanical bond and then apply two coats of Epoxy Primer. This does a few things. 1st) it protects any bare metal spots that may have been created during scuffing, 2nd) it has a strong mechanical bond with the scratches in the panel, 3rd) if the next product is applied within the re-coat window, it offers a chemical bond two that product.

3rd) I would then apply two coats of a polyester primer (sprayable body filler) during the re-coat window as specified by the manufacturer. The poly primer does not shrink and will fill the subtle imperfects. If the imperfections are more than the poly primer can fill, I would then use a body filler to correct as needed. At this point I have blocked the panel to 180 or 220 grit which creates tooth for the next product to grab.

4th) Once the panels are perfect, I would apply a urethane primer, which seals the porous body fillers products below it. Also, if they where perfect to begin with, I would have skipped the body fillers in step 3 and just applied the urethane Primer to the properly prepared EDP. Then I would block the urethane primer to what ever the manufacturer recommended. In my case 400 grit which is what the base coat needs for mechanical adhesion. If the finished color is all uniform, I could apply base directly to it or I could apply a reduced epoxy (which acts as a sealer). Either way is fine but the epoxy will grab scratches on the panel better than base. Then if I apply the base to the epoxy sealer within the re-coat window I have a strong chemical bond between the two.

5th) next I apply the base.

6th) Last I apply the clear.

Again, That's the manufacture's recommended process for their line of products. Find out what the process is for the product line you plan to use and follow it.

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