[raposak]

My frame is badly rusted and it will take me a few weeks of grinding and replacing metal. My question is as i'm doing this, what should I put on the parts of the frame that I bring down to bare metal so it doesn't rust immediately as I'll be making repairs in sections. The frame sits in my driveway and there is no option to work on it inside (body is in garage). I plan on applying POR15 when its all complete. Thanks for any insight.

[nytrainer]

Black SPI epoxy (in my experience). Skip the snake oil (POR 15) and finish the epoxy with a quality chassis black or just leave it in black epoxy (even better IMO).

[raposak]

Thats good for when the entire frame is completed and ready to be sprayed, but I can't see mixing and shooting epoxy primer for a 1' section of frame as it gets done.

[nytrainer]

Any DTM (direct to Metal) primer worth using is going to be a 2 part (hardener or activator). Depending on the weather I've mixed SPI epoxy primer, used it, and then two days later was still able to use what was still in the mixing cup (covered of course and kept out of heat).
Any coating, even spray bomb primer, would hold off flash rust for a while but I wouldn't want that crap being my foundation layer.
I've used Ospho (you can google it if you don't know what that is) on bare metal panels which works well and super easy to use. Can't comment on other paints/primers that I haven't used but with SPI epoxy you must re-wet the areas you treated with Ospho with more Ospho (this could safely be done weeks later) and then rinse with water to neutralize area before priming with SPI epoxy.
Good luck with your project.

[70455HOVert]

Eastwood makes some stuff in a spray bottle that's basically just weak acid that's made to keep things from flash rusting after blasting.

[raposak]

Thanks guys. I'll look into each one.

[Judas]

People will disagree, but the POR-15 on my frame is close to 10 years old and still holding. It was stored outside for years and exposed to sun, rain, and snow.

What I've found is that when it works, it works great. And when if fails, it fails completely. If it doesnt adhere to the metal (like smooth new metal) it will peel off like a sticker. Crusty old metal- it sticks very good. I do wire off all flakes and then wipe down the metal to remove dust. For example, it did NOT stick to my control arms- the metal was still well-preserved and smooth (shocking actually). The paint delaminated like crazy.

I've also used Masterseries, which is like silver bridge paint. It sticks pretty well and doesn't seem to delaminate like POR-15 (much more scratch resistant). It does not seem quite as rust resistant as the POR though, with pin-pricks of rust coming through here and there.

I've used Rustoleum brush-on. it is crap. Extremely thin. Avoid!

Another that I am trying now is XO Rust brush on. Cosmetically, it sets up very nice with the brush marks flattening out and seems to stick pretty well. It's definitely thicker than the Ruseoleum and POR paints. Not enough time has passed for me to comment on it's rust resistance yet....time will tell.

Good luck!

[Mill67]

They sell a prep that etches any bare metal, and claim it makes the POR 15 stick to any metal surface.
Anyone try this yet?
I was going to use POR 15 direct on any rusted portions of my frame, and use the etcher in the smooth, non rusted areas, followed by POR 15.
http://www.por15.com/POR-15-Metal-Prep_p_15.html

[bdk1976]

Just get phosphoric acid from the hardware store instead of paying for the same thing with POR or Eastwood labels.

Spray/wipe it on, let it sit for a bit, then rinse off with water (or you can rewet with acid and rinse later as someone else suggested).

You may want to buzz over the treated metal with sandpaper just before painting depending on the coating you are using along with your comfort level.


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[Judas]

I used the etch, and was completely unimpressed by it. While it improved adhesion, delamination was still a problem.

It sounds crazy, but I really think the best way to get POR to stick is to set something out till it gets a nice, brown coating of rust then brush off the loose flakes.

My frame was basically "brown"; completely coated with rust and yes- had some pits too. This is where it worked best. On sheetmetal, even etched sheet metal, it was very poor and peeled off.

I hope that I am not coming across as endorsing it- I am just presenting the facts as it pertained to my use. The choice is yours. Honestly, I would go with either Masterseries because it 'stuck' wherever I placed it. Also, I did NOT put the black top coating on which might be why I had some rust points. I think the XO Rust might be worthy too, but I just havent had it on the car long enough to be sure it will hold.

Good luck!

[bdk1976]

Best surface prep IMO is sandblasting, but not exactly what the OP was asking. I agree he could probably just leave it and POR over any surface rust....or treat surface rust when all finished.

Sandblasted my 67 2+2 frame last summer with black beauty and used POR - came out great and stuck like glue.


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[Murf]

I've had great luck with this.

http://picklex20.com/

Kept rust from forming on some bare parts I had laying around for 2 years.

Good luck with your project.
Murf

[Willshire]

I have had great luck with Eastwood 2 part epoxy. It's also priced right. i had the same issue as you, being outside. I started in the morning, cleaned the frame to the firewall and epoxied it. the next weekend i did from the firewall to the back on the right side, primed, then the left side.