Epoxy Primer

[Taylormade]

I'm getting conflicting messages on using epoxy primer on a sandblasted fender (1932 Dodge DL). I want to seal the fender as it's going to be awhile before everything is painted. I'm using Nason Ful-Poxy. My local paint shop insists I need to sand the already sandblasted fender with 80 grit to scratch it and get a good tooth for the primer. They say shooting epoxy directly onto sandblasted metal is a no-no and the primer will peel right off the surface once it dries. Several paint/bodyshop forums say just the opposite - that sandblasted metal is an ideal surface for epoxy application.

Anyone out there with real world experience that can offer some advice? I have a nice sandblaster setup and the fender is blasted and ready to go. The thought of having to sand the entire fender at this point is a bit discouraging.

[Tom M]

Taylormade,

I used their primers and trust what the user here have to say about it.

http://www.spiuserforum.com/showthread.php?682-Sandblast-then-Epoxy&highlight=sand+blast

[Dwight Romberger]

For real world advice about painting check out this guy's videos. If you are not offended by some of his "earthy" language, I have found his advice to be spot on.

Sorry, I had the wrong link

Dwight

Edited July 16, 2013 by Dwight Romberger (see edit history)

[Guest billybird]

I've always used PPG self-etching epoxy primer.

i always sand a blasted part before applying the primer,BUT, only a token job to remove the gritty feel. This takes almost no effort. Then clean with a good solvent, tack it off lightly, {tack cloth} and shoot. 20 years with this method and no problems. Don't sand epoxy primer until you are ready to paint as it may loose it's sealing qualities. The main thing is to use "self-etching" epoxy primer.

[jpage]

I had my body primed with an epoxy primer right after sandblasting; it's been about 5 years now,it's still in primer and only show a little rust on the bottom facing the cement floor. I have had no adhesion issues and you can use filler right over the epoxy if you wish. I've also used self etching primer and that stood up well also and again over freshly blasted metal. I'll sand it off again when I get around to the body work. That was about 6 years ago with no signs of rust!

[Taylormade]

Thanks everyone. I guess I'll just run a DA with 80 grit over the blasted metal to be safe and then shoot the epoxy. I know I could probably get away with spraying right on the blasted metal, but paranoia sets in when it comes to me and paint adhesion.

[Taylormade]

I got this reply from Dupont on primer application:

Hello,

The epoxy primer will have better adhesion over an abraded surface which

includes sandblasting. Sandblasting can lead to a coarser profile which

can telegraph up through the primer. Using 80 grit will help level the

coarseness resulting in a smoother appearance.

The important thing is to get primer on the bare metal within a few hours

to avoid corrosion.

Thank you for your interest in Axalta Coating Systems

Todd Brenner

Technical & Color Specialist

So, it looks like blasted or sanded metal is fine, with the sanded giving a smoother surface to the primer.