How does everyone deal with metal that has pitting in it when doing bodywork? Do you replace it, just use filler or what? Working on a project right now with alot of the body has light to medium pitting that gives it a rough finish....how have you dealt with it in the past?
If not replacing the panel I like to use a rust converter, like POR15, on these areas. The rust converter may even fill some of the smaller pits. Then, after that, a skim coat of filler should do the trick. Of course, new metal is usually the best option.
Disclaimer: I am not a professional body tech. Having said that, I have worked on a lot of old tin. As mentioned the depth of pitting may drive the repair vs. replace. In any case I have found the getting the rust out of the pitting is the key to a lasting fix. Depending on the size of the area I have used a chemical rust remover or gentle blasting with a spot blaster. Once the rust is out you can access the depth of pitting and go from there. Unless it's real deep, primer and filler works. A few gentle pokes with a pick will test the strength left if the pitting looks deep.
First, get the rust out. Can be done with sandblasting, or some sort of acid dip. Just grinding the surface off will not remove it from the pits, so don't waste your time. I don't believe in "rust converters". Then, if there are no holes, just pits, a high build primer should be just fine. If there are shallow dents or other surface imperfections, use some filler on the nice clean bare metal.
This thread got me thinking and wondering......wondering what something like this would cost to own and operate! It would be a game changer if it really works and it wasnt cost prohibitive.
I am doing the body work now on my 41 PU and it has acne all over the front fenders. I bought Evercoat Super Build polyester primer and a new spray gun to apply it with a 2.5 tip. Basically spray on bondo. It goes on pink and sands gray so it has a built in guide coat basically. I am painting the truck gloss black so prep is everything.
Here's a video I did 2 years ago. Did not win an Academy Award for this one. This is how to level heavy pitting and pinholes. I threw this Fender outside the shop and it's sat in a couple of feet of snow this past winter it still looks good. For years people have stolen the pigment from the bottom of the can to fill in pitting in so I told them to give them a whole can of paste for situations like that.
Thanks for all the responses everyone. Gonna try to get a few pictures of the areas I'm talking about, I'm thinking high build primer may be enough in most areas, but there are a few that are more severe.
I’m a fan of epoxy primers as the first layer over bare metal, after the pits are free of any rust of course. We mix up a bit of PPG CRE epoxy primer and don’t thin it. It’s one of their industrial coatings. Builds much better that DP epoxy. Brush a couple layers on the pitted area and let it dry a couple days or so. It sands well. After we’ve sanded the area with somewhere around a 150 grit to level off the pits, we’ll then shoot a couple coats reduced just a bit on the area. Works very well and is a very tough.
My coupe was a rusty pile before I built it. There were many large areas of pitted metal from years of setting outside. The areas that were still solid, but pitted, got sanded with 36 grit to get to the bare metal surface. The area was cleaned in accordance to the rust converter instructions and two coats of converter were spread. That was wet sanded with 400 paper and cleaned again. Then the areas were primed, and skim layer of body filler was used to cover the area. After the body work, paint was applied. 10 years later I had to address an area I didn't fix the first time. When the finish was removed, the area with the pits still looked the same as it did 10 years before. The new work was completed and the whole area had the body work done again. As far as I'm concerned, the rust converters work pretty well, but you need to follow the directions on the labels. Gene
Epoxy primer it's not airtight. Automotive zinc phosphate epoxy primer does around 700 hours of salt fog before it deteriorates. The sealer I use is airtight and will do thousands of of hours of salt spray. In the old days when we painted the car , a historic car with the idea of preserving it for time and memorial we could not afford to take a chance with rust returning. In those days we would put 14 coats of lacquer plus primer sanded every coat and then cut and buff. Nobody wants to go through that again That was my biggest fear. Now granted the cars that we drive usually have a sheltered life . their garage kept , the kept out of the elements , there waxed and have a great life. Now when you keel over where will this car windup ? Every week I see an obituary and I see a lot of cars sitting and rotting. As Remo would say why take a chance?
The Three Coat Polyurethane System is one of the most powerful anti-corrosive systems. It's used by the Armed Forces. Bridges coated with this system will go 15 to 20 years or longer. They got a call the other day from the fishing boat Mary F out of Oregon, they put in a pretty good-sized order . The captain said that they got nine years out of the last load. I was lucky to discover industrial primers three decades ago I use an industrial primer ,automotive color coats because of the great pigments The last clear I used is what they use on the bottom of jet aircraft for stone shipping .Right after I painted the car I dropped a Sears timing light on the front fender . It dented the fender but it didn't chip the paint
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