bluecab

I am getting ready for primer on my Toro project and there is a bit of surface rust on the bottom of the rockers and trunk drops. Can any of you advise me on primer use for these areas? Should I sand to bare metal and then cover with the PPG DP90 Two part primer or should I scuff it less and spray some rust converter primer on before the Two-Part primer? Does the Two-Part primer seal everything that is under it, including other primers? I have read some of the discussions about putting body filler under VS. on top of epoxy primers but I don't have any idea how this works with primers and old factory paint from the 60's

68442

Rust never sleeps. You must get rid of it regardless of what you put over it otherwise it will come back to haunt you. A two part primer is not a sealer to underlying paints or rust. An epoxy is used as a good sealer for questionable "SOLID STABLE" older paints/fillers then use your 2K primer over it. Lot of debate with plastic(Bondo) over epoxy I have been doing it this way for 20 years with no problems.

brddg

Remove the rust thouroughly by sanding, sandblasting or using chemicals such as naval jelly or muratic acid. most 2K primers are not dtm (direct to metal) so you will need an etch primer or wash primer on the metal first. you can epoxy prime dtm but it does take much longer to dry than an etch primer and therefore would have some risk in the application of a 2K primer over it unless you wait for it to cure and then sand it. As far as using it under the filler I never saw any advantage that justifies the extra step. High quality fillers have great adhesion to metal that has been prepped with 80-180 grit and shouldn't have any corrosion issues if primered and topcoated correctly.

69442C

Given the description of some of the panels having surface rust, I would say you are not ready to spray primer on the car especially if you want to achieve a final result like that in your photo. Rust converters will convert and seal rust to prevent the rust from getting worse but it doesn't make it go away and it will not smooth the panel. And you should not use a filler primer to try to smooth out poor prep work. Remember, when you paint a car, roughly 90% of the paint job is the prep work to the body and its the prep work that separates some paint jobs from others. You should sand down any surface rust and make sure you remove all of it. There can be pits in the metal and if so the area should be lightly blasted to remove all the rust from the small crevices. Once the panel is fully prepped, you can spray it with the DP90 to seal the metal. Some 2 part filler primers don't always bond all that well to bare metal to the best way to do it is seal everything with epoxy and then follow up with filler primer over it.

If the panels still have original paint on them, you need to be certain the paint is still adhered well and that it does not have any cracking or checking going on. If so, it must be removed. Eliminate all the problem areas before any primer, epoxy or filler primer, is applied if you want to have a nice result that will last for years.

You can do body work with filler over epoxy primer or under it and it comes down to preference. If you had a body completed stripped and you wanted to seal it, you would spray it with epoxy to seal the metal. When it was dry, you would scuff the areas needing filler with 100 grit paper without sanding through it and apply the filler over it. The thinking here is the metal below will stay sealed. However, if you are working on a few panels at a time, you can do the filler work and then apply epoxy over the panel and then follow with filler primer to block sand the panel. Be sure to follow the instructions on the DP90 as you can spray I, let it sit for approximately 30 minutes and then go right over it with the filler primer without the need to sand the epoxy. But if you let the epoxy fully dry, you will need to sand it before applying the filler primer. DP90 can also be thinned and sprayed as a sealer and allowed to dry for approximately 30 minutes before you spray your color top coats.

Brian

coppercutlass

BTW imo The dp90 on the body panels is such a waste of time and money. Dp90 is an epoxy if i remember right. It resists chemicals. This primer is great for under body, frame , fire wall ., areas that will actually come in contact with solvents. I would use an etching primer or a high build primer that has corrosion preventitives and etching qualities like the ncp270 for panels . A light coat will protect then when you body work is done under reduce it 10 percent and lay it on to have a nice surface to block out.

steverw

I use DP primers and have since the mid 80's, on bare metal. I think its excellent! My old paint guy told me years ago that PPG says it gives a 100% moisture barrier. They also say body fillers will stick to the DP better than metal. This is just what I was told many times by the guy that sold me paint. He went to alot of PPG classes. If you do put fillers over it, I suggest putting another couple of coats of the DP over the whole car, once all the body work is done. You have up to 7 days to top coat DP epoxy primer, after that it will need to be lightly sanded and reapplied. Then you can put on your 2K primers and block sand the car until its where you want it, then apply your paint.
As stated above, DP primer will not solve rust problems. Get the metal sanded to clean metal, blast it, cut it out and replace it, what ever it needs. If you have just a VERY small amount of rust like in pits, I might be ok with rust convertors. Just be sure you treat it good and let it dry before you prime over it. Of course all rust gone is the best. The one rust convertor i did like was called One Step, but i cant find it anymore. Also as stated above, the prep work is 90% of the paint job. Darker colors will show imperfections more and will show dirt more.
Again you can also put it over older paint so long as the paint is on the car good, not peeling or crazed, cracked paint. You would need to sand ALL the old paint first to remove the top layer, something fairly coarse like 220 to 320 to give it "tooth" for the primer to sink into and grab on. Others may have opinions that are likely good as well.
Good luck with your task, I hope it comes out looking like that pic.
Steve

coppercutlass

I always like the dupont variprime etch primer. I would normaly do minimal coveragve. Now here is a good story. The driveshaft that's on my 72 has been in use for 7 years and its only coated in dupont vari prime. I drive it in the rain no rust at all . When I was doing the body work on my 72 my car sat for 7 months and I saw no rust and all it had was a light coat of vari prime and ppg k36 primer . When I had a steel hood it was in primer for 2 years . I regularly washed the car and I saw no rust . I'm not saying the dp90 does not work but primers have come a long way since the 80's . Many urethane primers are dtm and have rust and corrosion resistant properties which make it a product with more than one use.

oldsguybry

I never sprayed epoxy before . I was a painter and know how to use HVLP along with mixing varnishes and what not so you don't get the orange peel effect . I noticed that epoxy's have three parts to them ? A hardener , reducer ? i was a bit leary of trying this out since It's been a while since I painted and never had to mix three components together . With how expensive this stuff is I went and bought a spray can epoxy that will mix the components as you spray . This would be a lot more expensive I would imagine . I would love to get some epoxy on my car eventually .

bluecab

So, it seems from the replies that I should be sure to get out all the rust and then use etching primer under the DP90?
I guess using epoxy primer is overkill but I have never painted a whole car before and bought the DP primer after reading about the various PPG products.
My plan at this point is to finish the body repair and get some primer on the bare spots to avoid flash rust and then coat with the DP primer.
The car may stay in primer for a season before I get the time to put the finish coat on, one of the reasons I thought an epoxy primer would be an advantage.
I am trying to use compatible products from a single manufacturer: is PPG Deltron K38 hi build primer and the PPG Concept acrylic urethane going to work ok?

69442C

Etch primer is old school and is not widely used anymore. DP primer replaces etch primer and is a better alternative to completely sealing the metal from moisture. DP primer, while epoxy, is not a chassis epoxy paint and is not intended to be used as a means to protect against chemicals. It is a moisture barrier and it is to be applied directly to metal and it sticks like crazy, far better than other primers. This is another reason it is more widely used today. DP must also be top coated. The correct sequence is sand to bare metal to get rid of any rust, clean the panels with wax/grease remover, apply DP primer, use PPG 3035, K38 or K2 high build primer to block the panels, apply a sealer, apply color coat and clear with 2021 clear if you want a really quality paint job on your car. Your final sand on the primer before applying sealer/color/clear will be with 800 grit paper. Be prepared as these products are not cheap and you will spend close to $2K for all of the materials if you do it correctly. Given you lack of experience, I would suggest you give thought to a different direction. If you want to spray the DP and high build primer that may be OK but consider letting someone else do the finish work. Or, look into paint products sold by Eastwood. They sell the same types of products such as an epoxy primer, high build primer, sealer, color and clear for significantly less money. This way if you want to do all the work yourself and you screw up, you don't have a fortune tied up in paint materials. Painting is more difficult than it appears and a black car will show every flaw in the prop work and poor body work. To me, a car that is painted with the best products but has wavy body panels and sanding marks ends up looking like a cheap paint job, especially with black. As I mentioned before, you will spend 90% of your time on the prep before you even think about applying color. If you do it correctly, use quality products and maintain the finish correctly, you will have a final product that will last for many years. One more thing: since you are using a solid color like black, you can go with a single stage black which means you spray the color and do not apply the clear. Single stage colors can look fantastic once they are wet sanded and buffed, like you would do with a clear finish.

oldsguybry

This info is priceless ! Thanks Brian .

Rocketguy

It is about using a product for the specific purpose at hand. Each paint product is carefully designed for a particular purpose.

There are primers (like DPLF) that are designed for maximum adhesion and metal corrosion resistance (a heat box, a frame, a fender, a radiator top plate, whatever; it is all steel). These are not designed to have the properties of primer surfacers or body fillers; in fact they really suck to sand.

Other primers like primer surfacers are designed for maximum film build and easy sanding. They are not designed for maximum adhesion or metal protection like DPLF type primers (though technically they do work for bare metal).

Body fillers are a different product yet designed for another purpose. I hope your getting the idea

I agree with as stated above; the best results come from clean Clean CLEAN bare steel, then catalyzed epoxy primer, then body filler, then catalyzed primer surfacer, then catalyzed sealer and then catalyzed top coat. I painted my 442 (and dozens others) using this exact procedure the day after Christmas '95 and it still looks excellent.