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Hey guys I had a question. Part of my car is already bare metal while parts of it still have the old paint of when it was first bought. Now im told to prime the bare metal part only but I'm not sure if that will really level out the surface of the car. Also, its almost impossible doing it that way for my car because the bare metal parts of the car are random so it would be impossible to mask it off and then only prime those parts. I was wondering if I could priming the entire car (so I would be priming the bare metal parts and the already painted parts) layer by layer that eventaully they would both become the same shade of the primer colour (which would tell me that they are now level). Will this idea work or does anyone have any other ideas/solutions on this one? Many thanks

P.S I did use a paint stripper (came in spray form) from my local Canadian tire (the only thing they had to strip paint) and it didn't work out that well. If anyone has used a certain product/chemical that worked amazingly, please do tell!



The short answer ( as if I have ever done that... ) is that you should get out your powersander with a nice 180 or 240 grit paper on it and sand down the surfaces to narrow the gap between the edge of the old paint and the areas where it is already bare metal. This will at the least feather the edges so that they blend in and are not so prominent.

Then I would probably use the Brightside primer ( which you can roll on ) to lay down a coat of primer over the entire surface. Now.. the reason I am specifying the Brightside primer in this instance is that it is thicker when rolled on then some of the areosol spray bomb primers which go on pretty thin. This would be your best shot at getting the bare metal surface to level off with the sanded painted surfaces.

Once you roll on your first coat of the Brightside primer you can let it dry and then put the car under some sunlight and start inspecting to see if you were able to get one level surface coating where you can't detect where the bare metal layer was and the sanded painted surfaces were.

IF you are able to spot slight differences in the elevations of the two surfaces, I would be tempted to lay down a second coat of the primer.

At this point you would have 100% color coverage of the primed surfaces and enough of a build up of primer so that you could now wetsand the primer with a nice 1200 grit wet sanding paper to smooth out the surface.

I would probably want to put the wet sanding paper on something wide and flat - with a bit of firmness to it. The idea here is that you want the wetsanding paper to maintain a wide flat surface for when it is in contact with the primered surface. IF you used a flexible backing or too small a surface the wetsanding would ride up and down between any surface deviations and not really help the situation any. But with the wider and firmer wetsanding, it will be spread over a wider surface and tend to produce a smoother overall surface.

Imagine this : YOu are on a bicycle and you ride the bike into a pothole. The odds are that the thin bike wheel or tire will drop down in to the pothole. BUT if you had a nice wide low profile car tire on your bike, like a 235 x 50 x 15, it would tend to ride over the pothole and give you a smoother ride. So in the example about the wetsanding, you won't be riding the 'potholes' ( if any ).

But I suspect with two coats of Brightside primer rolled on to your car there will be sufficient build up of primer that there probably won't be much in the way of potholes.

IF you go with a spray on primer, I don't think I could guarantee that you would be happy with the results. It simply can't lay down a thick enough layer of primer.

And to answer your other question... primer tends to 'build up'. That means when you are spray primering, it is building up the bare metal surface at the same rate that it is building up the painted surface. So they tend to go up in height similarly, leaving the original difference in surface elevation still visible. AND if you go and spray extra primer on the metal surface to try to level it up with the painted surface, what you will notice is that it tends to crack as it dries. ( the only way to avoid that is spread out that type of spray over a couple of days so that each previous days priming has fully dried ).

Just to confirm some other questions :

Yes you can substitute the liquid Rustoleum/Tremclad primer for the Brightside primer when rolling.

Yes... you can use either primer with either type of paint. There are no problems in compatibility.

AND don't forget that you can add 15% of paint to your primer to help get it started at pre-coloring the primer for when you start actually using that color of paint on the car. Be sure to allow a little extra time for drying when you are adding that tinting touch of paint to the primer.

OH... and bye the bye... the only canned paint stripper that I can think of that would really rip the old paint down to metal is AIRCRAFT PAINT STRIPPER... That can rip a paint down to metal pretty quickly BUT IT IS NASTY stuff to work with. That stuff eats rubber, hands and driveways.

Because you mentioned that you had attempted to use a 'stripper' on your old paint - I would strongly suggest :

a ) take a bucket with some dish detergent in it and warm water. Take a clean cloth and wash down the car thoroughly. I know it will look funny to your neighbors giving your patchy looking car such a loving sudsy washing... but do it. Then rinse it down like you were planning to eat your dinner on it... !

b ) once it dries, give the entire body a really thorough wiping down of the surface of the car with a rag that is damp with mineral spirits.

You really have to take this extra bit of effort to assure yourself that NOT A HINT OF that previous stripper remains embedded or absorbed in your old paint or in the old exposed primer. The dang spray stripper stuff is at this point a potential contaminant that may have an effect on your primering or painting. So be Mr Clean and get that surface contaminant free before you get moving on to the next stages..

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Last edited by Marq; 04/27/08 11:11 PM.