Primer question

[41chevy 74]

I’ve read everything I could fine about painting on here. When I get my frame washed down, scraped, cleaned and ready, I see where most people use etching primer, from a spray can. I plan on buying oil base I H red along with reducer and hardner. Am I right in assuming you paint red right on top of it since it says you don’t sand etching primer and it would be next to impossible to sand the frame anyway?

Next question on the sheet metal would I spray it with etching primer then regular primer after the etching drys? I’d planned on blocking the sheet metal and you can’t block etching.

 

[oldredrider 2,548]

I use 400 grit sandpaper on self etching primer. Gives a great finish prior to top coating. Just following directions on the primer can...

[WHX?? 48,800]

@Achto ? 

[Achto 27,512]

37 minutes ago, 41chevy said:

Next question on the sheet metal would I spray it with etching primer then regular primer after the etching drys? I’d planned on blocking the sheet metal and you can’t block etching.

 

You are on the right track here.

 

Spray your frame and rough parts with self etching primer. After the primer flashes off (looks dull) you can follow right behind with the paint.

 

Sheet metal - spray self etching primer, wait for it to flash, spray your sand-able primer. TIP -  I like to mist a thin coat of a different color primer on the parts once the sand-able primer has dried. When you go to block out the part, just sand until the top mist coat is gone. Lets you know where your imperfections are and also keeps you from missing spots

 

I finish sand with 400grit.

Edited December 8, 2021 by Achto

[41chevy 74]

I got it, thanks for your input, you’ve answered my questions.

[PetesPonies1 117]

Spraying top coat over primer without sanding is called wet-on-wet. Meaning, you allow the primer to flash enough, then go with the top coat before it totally dries or cures. I do this often with epoxy. If using etch, then it can be used that way as well, or if enough coats are used, it can be lightly sanded as well, with some 400 or 600. I will use some etch for burn throughs on primer, after sanding and before paint. 

[76c12091520h 3,608]

The only thing that should go on over etch primer is either some type of urethane sealer / high build primer in order to seal the surface, and not epoxy. The acid in the etch primer can affect dry times, cause blistering, or adhesion failure. Etch primer is designed for use on new or clean bare metal. If you use etch primer over existing paints or primers, all bets are off. 

[oliver2-44 9,710]

On existing paint, I have sanded it heavy 180 or 220 grit on things like the frame, lift linkage, etc,  Everything I paint gets sanded; If its hard to sand I use the coarse red scotchbrite.   some of its not easy, but I feel you need to get that oxidized top layer and any rust off. then i wipe it down with paint thinner or lacquer thinner. On sheet metal gets 220.  If I'm using rattle can I use Rustoleum High Build Primer, Allow to try then block it all with 360 or 400 grit.  Then I use Rustoleum Regal Red in spray can or I really like to use Regal Red in my spray gun with hardener.

Edited December 10, 2021 by oliver2-44

[PetesPonies1 117]

2 hours ago, 76c12091520h said:

The only thing that should go on over etch primer is either some type of urethane sealer / high build primer in order to seal the surface, and not epoxy. The acid in the etch primer can affect dry times, cause blistering, or adhesion failure. Etch primer is designed for use on new or clean bare metal. If you use etch primer over existing paints or primers, all bets are off. 

I've been painting a long time. I even taught Auto. I stand by what I do and profess. You change one thing about it, you might get different results. But the way I explain and use it, it works. If you think epoxy isn't it's own sealer, you don't understand epoxy.

Edited December 10, 2021 by PetesPonies1