Hi all,
For sometime now i've noticed that many of the rusty vw's out there that have 'restored' at some point that were done back to bare metal are worse off than cars which still have the original paint underneath (or on top for that matter ).
Now I know this is very generalised, and doesn't take into account of poor workmanship, materials and etc.

What are people's thoughts to this? I am now inclined to leave the factory paint where possible (off course some bits need to go to bare metal for welding and etc) in an attempt to reduce future rust.

-Rob

if there is nothing wrong with the factory paint then there is no reason to strip it, sometimes its hard to see the crows feet or crazy cracks in old paint and they will show up in the new paint, there is nothing wrong with taking back to bare metal, if rust comes through its usually due to poor preparation and surface rust building up under the paint

When I painted my daughters L I left a lot of factory paint on and just sanded the bare metal parts of repair work and painted areas together, the finer grades seemed to integrate the areas ok. I used "protec" industrial paint and remember the shop selling me a "blocking" primer so the top coats didn't react with the old paint, worked well enough, about two years now and I can't see any demarcation on the paint and no rust. If I was to do bare metal I reckon my patience would have been tested so hat's off to those that do!

go back to BARE METAL as most of the new paints react with the old type paints
even using the special sealers as such

We get quite a few 'project' cars come to our work to have the restoration finished. The owners want it just to be painted, as they did the body work over the last 10 years. The first thing we do is strip the body completely to bare metal inside and out using abrasive blasting - soda and garnet, depending on which part of the body. Then within 24 hours the body is metal surface prepared, surface acid etch coated, and epoxy sealed. This gives the body a totally sealed metal surface.

The biggest problem with 'bare metal restoration' is the time between starting and sealing the surface. Bog should not go on metal if you want it to last, as it absorbs moisture. Spray can primer absorbs moisture. Weld primer absorbs moisture. Only takes days, and the surface of the metal is already rusting. Flash rust at this stage is only going to accelerate later on.

My personal opinion is not to bare metal unless you have some serious rust issues. I bare metaled two cars recently and absolutely regret the last one. You will simply keep the panel beater and the bank manager happy. If your body work already lasted 30 or 40 years, why would you want to remove it all to start all over again? Of course bare metal might be required in some situations but be prepared to pay a LOT more for the job and wait a LOT longer for it to be done
Think carefully, if you don't have to do it, don't
Raf

By all means strip it back to bare metal if you're prepared to deal with what's under the paint. If you are trying to save money, DIY using 400 grit wet rubbing back the top layers. Spend the time working on one panel at a time. Rub back the layers of paint until you get to the original paint. Don't rub into the original paint and don't go back to bare metal at this stage just remove each layer and don't work just one spot on the panel, move all over the panel so you can see what's under each layer. It's like peeling an onion, and each repair will come to the surface. Basically you will begin to see whats hiding under each previous layer of paint. I have been amazed at the quality of the original paint that lies under a cheap nasty flakey paint.
If the paint is cracked with crows feet, or stone chipped with rust pits there is no option other than going back to bare metal, then treating the metal, primer etc.
If you start with the worst panel first, it's great experience. The end result depends on your dedication to learn from your mistakes. Everybody has to start somewhere.
You could bog it back up, or massage the metal back to the original shape. Both methods require skill and that comes from experience!

It's all going to come down to how much time you have as well as patience, your budget for the finish you are after and that's going to depend on the intended use of your car.
If you want the best, you will need to have deep pockets or know someone talented that will "help" you out (and that's after you've shelled out for perfect body work)

Cheers
D

It's great to hear how it should be done professionally. What kind of reactions can you get with new paints vs the old paint?

they can have a different thinner base and cause one paint to EAT into the other and make it flare and blister

after all you will probally spend around 15 to 2K on materials no use wasting that money if it reacts

I am doing the back to bare metal ..it is a time consuming job but at least I know what is below ....if you are anal about the car then it is worth it ...he says 3 months into it ..with plenty to go ...... I treat the job as therapy!

It may be worth looking at using Deoxidine [a phosphoric acid based preparation] on the bare metal, before any primer.

Deoxidine, De-Oxit, Deran A etc. are all phosphoric acid based preparation products. If your bare metal has been in the open air for more than 2 hours, then you must use this to positively remove any trace of oxidisation (rust). DO NOT use bare hands ever on any bare metal. Your hand sweat will start oxidisation of the surface invisibly in minutes.

How anal do you want to be? We take it very seriously at our work, and we know what it takes to be 100% sure there will not be any rust on the surface.

IMO you will not get better adhesion than the factory primer , so I always only take only what is neccasary of the original paint off,
if it hasn't lost adhesion after 40 years, it's not likely to in the next 40