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So after 4 years im done with cutting and welding and its time to put my baby back together. What is the recommended way to strip old paint and primer. I struggled for about 2 hours tonight on the trunk lid to get the old paint off. The primer underneath was the hardest. I tried flap discs, chemical paint remover, the hard spongy cup brush, and finally sand paper on a body block. Getting down to the old primer was easy but getting that off was a challenge. I finally gave up and blocked it relatively smooth with 120 grit. I then sprayed a few coats of epoxy primer on it. I can still see the areas where I didnt get all the old primer off. Is this something that will be taken care of with high build primer or do I need to take it down to bare metal. My plan is to drive the car for a short time in epoxy primer before sending it off to get painted this winter. You can see in the picture the areas that still have old primer on it (different color). Thanks again for the help.
 

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Have you considered sandblasting?

Very messy if you are doing it your own shop - depending on the anount of room you have - but very effective.

One of MY favorite gadgets for rust removal is an air needle scaler.
It does truely amazing things down to the tightest places.
A bit slow on large areas but still works fine.
If it NEEDS to be removed, the needle scaler will remove it.
I can't count the times it punched clear through the metal when I thought it was solid and found out otherwise.
I'd rather find out at that stage then find out 2 years after the paint is on...

That initial coat on sheet metal is EDP from the factory - Electro Deposit Primer.
Very tough stuff to be sure.
As long as the metal is good underneath the coat is generally just scratched up - 80 grit or so to give it some tooth - so that it will accept paint/filler on top.
Just be sure the metal underneath is good.

I'm down to that same position at the moment with mine...
 

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If that old primer is the original factory-applied primer, DON'T REMOVE IT! Nothing you can apply in its place will be as durable or will adhere as tightly to the metal as it does. It was applied at the factory using a process that's impossible to duplicate anywhere else. The best approach is to get down to that layer and then prepare it to apply the subsequent layers (epoxy, primer/surfacer, finish coats) over it.

Bear
 

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What Bear said, and never sand blast sheet metal. Nothing beats factory applied primer. It was the good, lead based stuff and applied with factory techniques that can't be duplicated in the field. Of all the cars I've had repainted over the years, the ONLY ones to still look good 25 years after re-painting are the ones where the factory primer was left intact. The ones that got stripped to bare metal always had rust pinhole issues after 10 years or so.
 

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I stripped my car to bare metal (sanded with 36 grit and sandblasted all the jams) and it was painted in 2002; looks as good now as it did then. Personally I would never leave old primer underneath anything new


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I'm gonna side with Bear and GeeTee on this one. My car was original paint under a coat of black epoxy when i got it. I ended up taking it all down until the blue was removed and i kissed into the primer. The only spots that i have had any issues with in 4 years with my paint are the spots i had to take down to bare metal for a few small dent repairs. Once the metal is exposed, if it is not cleaned and primed IMMEDIATELY it will start rusting especially if touched with bare hands. I would get down to the primer then spray a base coat of epoxy to do the final body work over. Never apply filler to bare metal.
 

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I had a '66 GTO taken down to bare metal all the way back in '82. I was at the shop and saw it with no paint anywhere. It was a ding free, dent free, rust free body, the straightest I've ever seen before or since. It was bare for only a short while in the shop before they primed it and painted it. It looked absolutely killer for ten years, then the small pin-points of rust started to show through the paint. Have not had that problem with any of my cars that had the factory primer left in place, and I'm talking one 29 year old paint job and one 21 year old paint job. They are as solid as the day they were painted. Absolutely nothing beats the factory applied primer....at least I've never seen it, looking at 100's of cars.
 
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