I know I've seen a similar message posted - but I can't find it on the board.
I'm going to have to do some bodywork to my 79 Bronco, but I don't have the time to do it all at once, and this truck is my daily driver. I've heard that if I prime an area after repair the primer will absorb moisture if it isn't painted. Most of this work will be a rattle-can job until I'm ready to paint the whole truck.
If I paint over the repaired and primed areas between work sessions, what kind of spray paint should I use? How many coats would be needed to keep the moisture out? Do I need to be careful about paint choice since I will be painting over this stuff (eventually)?
Thanks for any help or advice you guys can give.

 

It just isn't advised that you primer something and then wait 2 years to paint it that's all. Because primer is porous and moisture will penetrate it.

Rattle can will work fine temporarily and then once it comes time to actually paint you will sand it down and apply the true primer/ sealer.

Josh

 

I hope I won't have to wait two years to paint this thing, but who knows? My wife gives me a hard enough time about the way my truck looks, so after a fix I may cover the primer with a color just so it looks a little better until I can shoot it all.
I guess I'm worried about the compatibility of the spray paint with the primer I'll eventually shoot. I've never painted a vehicle, but will probably borrow the equipment and shoot it myself to save money (it's not a show truck).
Do I need to worry about whether the spray color is an enamel or laquer or whatever? Will the primer eventually shot on this truck stick better with any certain type of paint - or will it stick to anything as long as it's clean and sanded?

Thanks --sean

 

If you start working on an area and can't finish it, you should get some cheap enamal paint and apply enough to cover the work completely. Then when you find time to come back to it, remove all that paint and start working again.

When your finished with all the areas, you'll need to remove all the 'temp' paint treat any exposed metal with phosphate stuff from Home Depot under the Jasco name or Ras-O-Nil or Metal Prep.

Once the area is clean and dry apply a good coat of epoxy primer, I bought 2 gallons of PPG for $80 and I think NAPA carries some epoxy primer.

different primers won't work well together, the paint and primer from a can are design for shelf life and don't have the same catalyst that professional paints have, they end up not having the same toughness because of the catalyst (not to mention quality)

Some tips:
Consider all the rattle can paint to be a temp coverage just to keep moisture out or to be used as a guide coat when block sanding.

Bondo and other fillers ATTRACT and absorb moisture and must be covered

All rust and exposed metal should be treated BEFORE any bodywork or filler is added.

I've heard that NAPA sells some good paint for dirt cheap (about $100~150).

Beware of moisture in the line as you spray the paint, I have to redo a fender because of this.

Practic on a junk piece to get the hang of the flow of the gun, you want it thick enough to shine and cover completely but not to run or sag. With some practice, you'll see just when the paint looks ready to run but won't run.

 

Thanks for the replies. Are you saying that I have to take off ALL OF THE PAINT AND PRIMER that I apply with the can before shooting the truck? I'll have to sand down to metal, fiberglass, or filler? I'm not afraid of doing the work if this is what's needed - just wanted to make sure I wasn't misunderstanding.

Thanks again for the tips. --sean

 

Yes you must take all the rattle can primer off. I have been told that you can take the truck down to bare metal use epoxy primer than put your filler over the epoxy primer. I was told the epoxy will not absorb moisture and the filler can go over it. Then when you are ready to paint sand it just to roughen it up. Then spray a primer/surfacer (Thick primer that will cover miner imperfections) then paint. Eric

 

Sorry to say, but yes he's right. It's quite a bit of extra work but the only other idea is to rent or borrow a temp car while yours is down.

Your really don't want to mix the rattle can with the real primer or paint.

I've heard the same thing as Eric, apply epoxy directly over clean metal and you can also do filler over epoxy but don't forget to prep it first with something in the 80 grit range. I talked with a pro about my work and he suggested even rougher than 80 grit and to push REAL hard on the filler for the first pass so that it gets into the little scratchs for better adheasion.

Another tip: I'm using Acetone to clean with and I keep wiping until the towel is clean. One time saver is the two pass wipe down, one paper towel with Acetone second dry towel to pick up the Acetone from the work. This works faster and better than just one towel that smears dirt all over. Throw out the second towel often. I used a whole roll of towels on just the back half of the frame alone. A spot of oil can ruin your day.

 

You guys are killing me. What about the Ford factory paint? If I use a spray can to cover a fix and cover some of the factory paint, do I just need to sand down to the original paint when it's time to shoot the whole truck? Won't the new (real) primer stick to the factory stuff? I don't have to sand down to metal where the original paint is still intact, do I? Thanks again.

 

You can primer and paint over the current paint if it is in good condition and not cracked or peeling. Is it the factory paint or has it been painted before? If you use an epoxy primer I have been told you have to take it down to bare metal. You might be able to just use epoxy primer where you repair so it wont rust. Eric

 

I forgot to mention the most important things before painting is to make sure it is preped right and that it is clean with no oils or finger prints on the body. A finger print can show up a while after it has been painted. When I painted my dash I wiped it with laquer thinner before priming and painting but I didn't sand around the edges real good and it is starting to peel. It only has been painted for about four months. Eric

 

This might help some:
Right now I have both fenders primered and fully painted and sitting indoors for the last 6~8 months. One door is fully painted and the other door is painted on the inside waiting for primer and paint on the outside.

the reason this happened was that I was painting indoors in a custom made booth and it was the best weather and conditions I could get at the time.

It worked out just fine except that I wasted a bunch of primer and some paint. the problem is that you have to guess how much primer you need for the area you want to cover + a bit extra and the gun will not pick up the last 1/4~1/3 cup because of where the tube stops. I noticed how much of my two gallons of pimer was gone so I stopped and decided to do all the rest at the same time so I wouldn't have to buy more primer.

The reason I'm pointing this out is that you can paint 1 fender then the next fender and so on so that you have 1 day jobs out of each and wont have to worry about rain or driving etc... However, I'd expect to waste about 20% more paint/primer because of this, not to mention recleaning the gun each time.

In your case, I think this is best way to go, one panel at a time and worked until finished, you should be able to complete a door or fender in one day (depending on condition) As for the bed and cab I'd do what was described in the other posts as far as using cheap paint then removing it completely.

 

Thanks for the advice. I'd like to do this thing a panel at a time, but since I'm going to have to borrow all of the equipment, it's probably not practical. Besides, most of my problems are behind the doors - typical Bronco rust where dirt or mud collected at unions of inside and outside sheet metal. I have two good fenders and a driver's door ready to bolt on and paint, and the other door and hood have minimal repair needed.

Think I'll have to go with the sand it all off before I paint it for real method.

Here's another question... When I grind, cut, or sand the areas that are bubbled from rust, is there something I can do to keep the areas from rusting again? Some of these areas are impossible to hit with sandpaper from behind (example - the area between the rear fender lip and the interior sheet metal that meets it).

Thanks again. sean

 

I used Por15 for all the underside of the bed and cab as well as the frame. Because it has two drawbacks: 1. sensitive to UV (so don't use where you'll have direct sunlight or coat it) 2. you have to buy a second product to paint over it properly.

Because the frame and under bed don't see the light very often, I used it there.

On the outside body parts, I'm using Ras-O-Nil and then epoxy primer over bare sandblasted metal. You can use Jasco's rust converter from HomeDepot as well for about $8/qt then use a good primer then paint.

If it's an are that doesn't see light on a regular basis, I'd use the Por15. I researched this topic for quite a while and found that Por15 and Eastwoods rust products were the best.

 

Not all epoxy primers are the same. If you use epoxy primer I suggest you use the water proof PPG type. I have used this for my customers who need to take their cars before work is done. It works very well and we have not had any vehicles rusting prior to refinishing.

 

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As a follow up to the last reply, I understand that some primers actually seal with the application of water. I was told this was problematic if you attempted to wet sand the primered vehicle because teh water sealed the primer and the paint would no longer properly adhere. Anybody heard of this?

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