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Tue Oct 12, 2010 6:02 pm

Hey, all,

I have a noob question about preparing the chassis for painting.

I've been using a wire wheel to prepare the metal, and some areas are left smooth and shiny, but in other places there's some surface rust that isn't coming off. Here's a photo:

I was planning to use Rustoleum's Rusty Metal Primer, but the label on the can says that it is formulated to adhere only in the presence of substantial rust, and that the oil content of the primer will not allow it to adhere well to shiny, un-rusted surfaces. For that application, they recommend the white clean metal primer.

Here's what the company's website says about it:

Quote: Q Can I use Rusty Metal Primer on clean metal?
A No. The fish oil that is in the primer needs to penetrate into rust to seal out air and moisture. If there is no rust, the oil will rise to the surface making adhesion of the finish coat difficult.

You can't really see it in this photo, but to my untrained eye, it looks like the rusty and non-rusty areas are mixed together, in kind of a jigsaw puzzle. The whole rest of the pan is like that, too -- rusty spots in patches, separated by areas of clean metal.

Do I apply rusty metal primer to the rusty spots, and clean metal primer to the clean spots? Or do I use one type of primer for the whole thing? I only want to do this once, and I don't want to screw it up.

Tue Oct 12, 2010 6:12 pm

there are many choices for you. i like marine clean, metal ready and por 15. just scored some ospho so i'm experimenting with that acid wash. good luck

Tue Oct 12, 2010 6:45 pm

i would buy a small sand/media blaster. for bare metal i would use etching primer. if has rust would use por, but only if i couldnt get the rust off. doing some old doors making it suicide and chopped, gonna put por on the inside of the door.

Tue Oct 12, 2010 7:00 pm

I usually treat the rusty areas with a rust converter, then use epoxy primer.

Tue Oct 12, 2010 7:21 pm

i just stripped a whole floor pan, new floors and it had the same kinda rust all over it after i used the wire wheel.

i used the POR-15 line and i loved it.

Tue Oct 12, 2010 11:38 pm

Im not much when it comes to VWs, but Ive done a fair bit of bodywork. Just like LowNslow said, rust convertor on the rusty parts(follow directions closely) and epoxy primer over that, That is the best way to do it You could also use etching primer over the bare metal but epoxy primer is the best. It completely seals the metal, sticks great and everything sticks to it.

Wed Oct 13, 2010 11:41 am

Thanks, everyone. It looks like a rust converter is the step in the process that I have been missing.

Tue Mar 20, 2012 6:11 pm

Sorry to jam my foot in the door just as it closes here, but I have similar issues; my wheelhouses, pan bottom, and inside spare area have the clean metal-slash- rust combo, and my pan inside is shiny, new looking black from the factory (1960), but the channel pressings, or low spots, are all bright orange with surface rust, and it is pitting a bit into the metal. I am not doing a pan-off, and want to leave the car as original as possible, leaving the black finish where it has done so well for 52 years. Is there a way to just scrape and sand at those pressed channels and not have to remove the undamaged finishes on the pan?

And then, what is the best rust converter to use?

Tue Mar 20, 2012 6:33 pm

My .50€ worth.
I wire wheeled what I could, sand blasted the areas wire wheel could not reach. Used master series rust sealer paint, then painted it with chase black paint. Turned out great.

Tue Mar 20, 2012 7:44 pm

If you've gone thru this much trouble, don't use rustoleum. Get POR 15. This is a paint that sticks to rust very well and seals it so it will not continue to rust. Paint over it with a two part epoxy primer

Wed Mar 21, 2012 12:23 am

dugsgms wrote: Im not much when it comes to VWs, but Ive done a fair bit of bodywork. Just like LowNslow said, rust convertor on the rusty parts(follow directions closely) and epoxy primer over that, That is the best way to do it You could also use etching primer over the bare metal but epoxy primer is the best. It completely seals the metal, sticks great and everything sticks to it.
_______________________________________________________

I agree, but I would blast sand/media all the rust away. If you leave bits of rust like you have shown, then Por15---but just remember Por15 is only the first step with that product, you must use their Tie Coat primer afterward only then can you use epoxy over all of that.

D.

Wed Mar 21, 2012 6:55 am

Personally I would wipe it down with laquer thinner to remove any grease and oil and stick with the Rustoleum Rusty Metal Primer.

I have been using that product for years with extreamely good success. I've NEVER had it come off of anything we put it on. it's good stuff and stops the rust!

It's also a lot more affordable then most of the other rust products on the market, and if you ever need to repair a section, that is also a very easy task.

We had a 356 dirt track car here that was built in the mid 70's. A lot of the car had been painted underneath with rustoleum rusty metal primer. The car got wrecked very early on and sat outside in an unpaved area until last summer. Thats over 30 years!

This car had NO side windows or rear window in it, and was never covered. So when we got rain and snow, it got inside.

When we rolled the car out last summer, EVERY part of that car that had Rustoleum Rusty Metal Primer on it was in just as good of shape as the day it was painted over 30 years ago. The rest - well the unpainted parts didn't fair so well, but fortunately most of the underside and interior of car had been painted with the Rustoleum Rusty Metal Primer. It is now being ressurected to live again!

Be aware, many of the other expensive rust products will not hold up well to UV light. So they have to be top coated if you ever plan on taking the car out into the light of day.

Wed Mar 21, 2012 9:28 am

I also use Rusty Metal Primer alot. It sticks very good to the rust, and I dont think it would be a big issue on the smoother cleaner metal. Just clean good with laquer thinner as mentioned.

What I DONT use that much is Por15. WAAAY over-hyped. That stuff will peel right off in many cases. It doesnt penetrate the rust that well IMO.

Ive also been trying the self-etching primer that is on the market now in spraycans. It seems pretty good and is supposed to be very good on the rusty spots.

Wed Mar 21, 2012 6:41 pm

Thanks for the advice! drscope, I have read a few of your posts about rusty metal primer, and you have been pretty convincing, so I have purchased some that I am using on items that are rust-pitted. Time will tell, I suppose, but before I start spraying or painting the RMP on more critical items, like the pans, I have got to ask pointedly about my inside floor pans. They still have primarily the factory finish (that semi-gloss black paint) but the channels that run in a grid pattern are orange-rusty and definitely pitted. Can I spray the RMP directly on the original black finish and expect it to stick? Or do I need to wire wheel it all down to metal, or maybe just scratch it up with 80-120 grit? The car you sprayed it on 30 years ago, I assume had some painted finishes, some scuffed, etc... I just want to be sure I don't make a mess for myself down the road.
Thanks for contributing to the thread!

Wed Mar 21, 2012 7:21 pm

If the car is all together - body on, I wouldn't use a spray can.

Buy it in a quart or even a gallon and apply it with a brush. If you have them shake it when you buy it and it's warm enough to paint, it will lay down very well and you really won;t have many brush strokes.

Using a spray can often creates a bigger mess as the overspray goes everywhere and the rest of the interior of the car like windows and headliner will get covered in red mist that won;t want to come off.

On your floors, just use a wire wheel or brush to lightly remove the loose stuff. Then vacume it up and wipe it clean with the laquer thinner and paint away.

It will stick fine to the shiney stuff, but you could always scuff it up a bit with a scotchbrite pad if it makes you feel better.

Just be aware it takes time for this stuff to really dry. It's NOT going to be dry in 15 minutes or an hour. It's best to let it sit over night before you do anything else.

And it will stink for a few days, but that will go away within a week.

If you don't like the color, you can always use other Rustoleum products to cover it.

Thu Mar 22, 2012 6:32 am

Rustoleum Rusty Metal Primer.....Is FANTASTIC..It will stick to just about anything that is cleaned and preped correctly.....It even sticks nicely to parts that arent preped too good. I always at least scuff the areas, with 80 grit, just to take the gloss away from any surfaces, and wipe it down with Acetone before application. The key is to coat to seal.
My biggest issue is supply. Most suppliers are always sold out of the gallons. The word must be out. Gallons are the best buy if you have a sprayer to use, if not buy the bombs.
I agree with drscope. It takes a long time to dry. Depending on temps and humidity, Ive had it take over a week to cure to point where it can be sanded.

Great stuff....

Thu Mar 22, 2012 8:51 am

Just wanted to point out one thing.

Rustoleum Red Primer is NOT the same as Rusty Metal Primer! They look the same and are the same color, but they are not the same product!

So when you go to buy, make sure you get the Rusty Metal Primer.

Thu Mar 22, 2012 9:03 am

I dumped a quart of Rustoleum Rusty Metal Primer inside my tunnel (rocked it back and forth to get even coverage), it adhered perfectly and appeased my OCD tendencies in that regard.

As for my outer chassis and pans, after sandblast and some wire wheel touch up, we sprayed on epoxy primer and followed up with a polyethylene single stage paint.

Thu Mar 22, 2012 9:32 am

I picked up an economy Schutz Gun for chassis application. Its like a undercoating gun. You can lay pimer and paint on the chassis, as thick or as thin as you want it. With the extended spout you can stick in places a brush wont reach.

Thu Mar 22, 2012 9:37 am

VOLKSWAGNUT wrote: With the extended spout you can stick in places a brush wont reach.

That's what she said.

I'm sorry, I'm apparently 5 years old. :oops: