[60sRacer]

Etching Primer provides a thin zinc coating that (slightly) penetrates metal surfaces (aided by the phosphoric or sulfuric acid etch), inhibiting rust problems. It should be used only on bare metal. It's recommended here is a variety of threads for a variety of uses.

Epoxy primers are catalyzed (two part) primers for use on bare metal. It's recommended her too.

Can or should epoxy primer be used OVER an etching primer coating?

Should either (or both) be followed by a high-build primer to make a smooth surface?

Robert

 

[Luscombe1940]

Good question.
I have very limited experience with this. I have decided to use SPI epoxy primers and other products. I understand the epoxy can be applied over other paints as well as bare metal.

Couple of links for you to check out.

The founder and inventor of the Southern Polyurethanes SPI products, Barry, will respond to cell phone calls any time any day including weekends to help with technical questions about his products. When he answered my call on a Saturday, that was good enough for me. One of my friends who is also on this forum and has been a bump dent and paint man for 20 plus years uses SPI stuff exclusively. Again, good enough for me.
I am sure others will have different opinions.

Epoxy Primer | Auto Restoration 101


Tech Sheets

Good luck.
Gary

 

[VeloceGT]

Great info just wanted to post so that I can find latter for reference...getting ready to restore a 1970 GTV and will need all the help I can get

 

[60sRacer]

Bump. Can anybody contribute?

Roebrt

 

[aralfa8589]

I work for a PPG/3M body shop supply store and have painted a bunch of cars, so here we go:
A very light spray of spray can etch primer on bare metal, followed by epoxy primer is the way to go. It is best to put the epoxy primer over the etch primer within a half hour or so. This gives the epoxy a good bite. Epoxy primers are not meant to be sanded. This combination will keep your car from rusting until you go to the next step, which is a high build polyester primer. This is the stuff that you block sand to get the super smooth finish-600 wet is good. Polyester primer is not a rust preventer, it fills scratches and builds surface. Two wet coats will fill 180 scratches! After sanding be sure to let it dry for a day or two in a warm environment as the poly primer is hygroscopic. Then you are ready for color coat, either single stage or base/clear.
Hope this helps!

 

[aralfa8589]

I'm only familiar with PPG products so:
SXA 1031 etch primer, spray can-just mist the panel very lightly
DP epoxy primer in various colors, one wet coat
MP 243 polyester primer, 2 wet coats

 

[60sRacer]

Thanks for the input. I understand that etching primers go on bare metal. If the epoxy primer should be used immediately, do you deal with body filler and smoothing issues after the epoxy and before the high-build primer? Or does the body stuff go before either primer?

Thanks

Robert

 

[aralfa8589]

My mentor in all this (he builds 50K '55 Chevy hot rods) did his metal work, then etched the bare metal and epoxied. Then filler and sanding then another shot of epoxy (with or without etching) over the repair (since you're back to bare metal all around the filled area), high build primer and final sanding. For small dents a lot of body shops put filler right over the top of the repaired bare metal scuffed with 180 (no etch or epoxy), sand and then use the high build primer. I've done the latter on small door dings etc, but the former is better. The modern fillers are pretty good as they are designed for fast production-insurance-jobs and don't shrink or crack like the older stuff. Just try to bring your metal out to where you don't need more than 1/8" of filler. 1/16" is way better.