sheet metal/paint technique question

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Stepper

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I'm planning to begin some (I think) simple sheet metal and rust repair on my 69 Dart. I've never done it before, but an feverishly reading and soaking up all the information and technical know-how that I can before I begin.

In the end, I'll plan to have the car professionally gone over and painted. But, I hoping I can cut down on the end cost by doing some of the grunt work on my own. Which leads me to this post.

If I repair a section, for instance either patch in sheet metal or simply just work out a dent and apply body filler, is there any long term negative impact to me using some sort of a spray can primer over the repaired area?

I know enough that bare metal shouldn't be left exposed. However, I won't be able to get the entire car squared away and repainted in a short period. I'll have to repair small projects here and there over time. So, I'm wondering if I can work on a small area and protect it with a spray can primer. I don't have an air compressor to shoot primer.

And finally, do you guys recommend a particular brand of body filler and primer?

Again, thanks. You guys are always great for this stuff.
Stepper
 
As far as the filler goes I would use a light weight filler just because it is much easier to work with than the bondo stuff that you find at autozone. You can pick it up at any automotive paint supply store. As far as the rattle can primer goes, duplicolor makes an etching primer in a can. I would use that over bare metal and filler, because it bonds really well to it and gives you a good foundation to work from. Then I would just spray over that with a duplicolor primer sealer until the car is ready to be scuffed and painted.

LOL. Look at mine. It is about 4 different colors of primer. I plan on doing the paint next spring, but I like to drive until that day comes.

ride3.jpg


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Nothing wrong with the rattle can primer, but I wouldn't leave it there. Primer is porous and will allow rust to start underneath it. After you've primered, apply some type of top coat to it, maybe rattle can it the color it is now.
C
 
How do you plan to do the metal repair without an air compressor? Do you have access to an air compressor? (Friend? Rental)? If so, here is an idea you can try. Get a cheap paint gun ($20) from harbor freight. Buy a quart of a good filler primer that has corrosion resistant properties. I can suggest one from PPG. NCP 270. It has great filling properties, and awesome corrosion resistance. You can put it over bare metal and is a 9 out of 10 for corrosion resistance.

If you are going to take the time to do all of the bodywork and prime it with rattle can... you will eventually have to sand the rattle can primer off, or the bodyshop you hire will have to. Then you will have to prime with an appropriate primer. So why bother? Just do it correct the first time. The reason you don't want to prime with a rattle can primer is that when sanding it off again you will be affecting your body work. You will eventually break through the primer and start to sand into your already completed body work.

So, that being said, if you have access to an air compressor, do your body work, get a good primer, and spot prime each area. It will hold up just fine as long as it isn't seeing severe weather.

Lastly, etch primer is not meant or even recommended over body filler. It is "acid" based and eats its way into METAL. That is how it gets such good adhesion. It is put on very thin, "see through" coat. And has little to do with corrosion resistance. It's primary function is adhesion.
 
Most rattle can primers you buy at chain stores are laquer based and are not compatable with urethane or epoxy primers that would be used for the over all paint job. They will soften, bubble and lift if the urethane/epoxy primer is sprayed over them so they will need to be sanded off before final paint adding to the cost.

I recomend you go to any Autobody Supply store and SEM has a line of rattle can primers that are intended for spot repairs and will be compatable with urethane/epoxy primers.

Also, as previously stated primers are porus and if the car is kept outside will not protect it from rusting again unless you use an epoxy primer then it seals.
 
UPOL also makes a line of aerosol's compatible with professional paint refinishing. You'll find them at the jobber too.
 
please do not use any rattle can primers. I work at a body shop and we just had a 72 stang came in that some guy did all his own work...terrible.

First off, before I started doing this kind of stuff I was all for DIY, but after having to fix peoples stuff its a REAL big hassle, I can even see your point of view of wanting to keep costs down but a paint job is only as good as the products underneath it. Cheapo primers from a can(maybe not all but all I've seen) have NO FILL, its as I put it basically a thick guide coat. Say you weld in a patch, and say your a ok welder, and have no access to sand blasting, well when we get done welding we grind it down then sand blast the seam to inspect for any pin holes, make sure all of these are gone, then apply a fiberglass reinforced body filler, typically called mars glass or dura glass, over the weld seams to make them water proof and resist cracking. Oh and never apply any filler over any paint, glazing putty can be applied over paint as long as it is scuffed.

The best method to start out in my opnion would be to first get an air compressor, even rent one and it will be fine for just shooting primers but probably not ok for paint/clear cause it wont keep up on the air pressure. In my car I'm stripping ALL of the paint off of it, you never know what some 'hack' did back in the day or if that paint isnt going to just flake off some day, better to be safe the sorry, So get all the paint off then start by pulling dents using a dent removal gun or welding in patches, if for some reason you have to do the old fashion way of pulling dents of drilling a hole and using a screw to pull it out, weld the hole up, there are all sorts of old cars out there fixed this way and have 'worm holes' going though the metal with mud hanging inside, terrible way to fix things. Use a good quality body filler no 'bondo' and a good glaze, it does suck since I know its expensive but hey these things are expensive as hell. After the body work is done, assuming you didnt strip the cars paint, We apply polyester primer, it has a high build and sands great, Its actually Transtar brand, all of there products are great along with Upol Part number is 6541-g I believe, works great, Then block sand your work, along with feel it every way you can, up and down, left right, side ways, I say this cause Doing that mustang at work, the guy felt stuff Horizontal, which was ok to say the most, but once you felt it up and down it was way messed up.

Oh and I was going to mention, about primers, do your body work apply epoxy primer or a high build primer from a roller, and that way no need for a compressor, a body shop can just pick up where you left off and you know the stuff will hold out problems(epoxy will anyways for sure) Then the body shop can just sand it(epoxy) spray a blocking high build primer on it and start off where you left off, That would be the best way for a DIYer to do IMO. No rattle cans, no bondo, no problems!

I know I typed a book here for you so i'll stop and allow you to ask questions if you want Pm me is typically the best way since I may forget about the thread.

Good luck,
Jack
 
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