Guidance on paint and rust issues

[3 pedals]

Hi all, got a few areas on my 79SC with checking, crazing of paint as well as some rust areas where the PO had a crappy paint job done and it's flaking off.. I took one area and sanded it down to bare metal, wiped it down with mineral spirits and applied etching primer to the area. I have some filler primer I was going to put over that but don't know if the spirits is going to cause a problem later when I go to re-paint the car. I've got to do something to arrest the rust for now. I'm assuming the areas that are checking and crazing will eventually have to be taken down to bare metal also to prep those areas to paint. Am I going in the right direction? Thanks, Kip

[962porsche]

mineral spirits is a product you never use on a vehicle for any reason in any place for any purpose .
if you have bare metal and need to wipe it down you would want to use a metal wash product made for doing such a task. if it's a premiered or painted area and you need to wipe that down you would use either a pre paint cleaner or a grease and wax remover again made for auto body repairs.
when it comes to an etch primer in many cases it's best to use a epoxy primer.
etch primers are good for a car that will be sitting in primer for a long length of time say a year or more. this way the etch properties will have time to be less aggressive and not want to attack the other undercoats or top coats your looking to apply over the etch primer.
epoxy and etch both are good for protecting the bare metal it's simply etch primers are more aggressive. there is also the fact some undercoats and top coats can never be applied over a etch primer.
RE checking or cracking top coats:
in some cases you do not have to strip to bare metal some times you will find the undercoats ( the factory primer's and sealers ) will be ok and no need to remove them.
the factory undercoats are some of the best in quality and how they are applied and it's good if you can leave them. if you need to strip to bare metal you can replace them with a quality epoxy primer. the down side to stripping any car is when you do so to a car that has a galvanized coating your also going to be removing that.
many Porsche owners are hooked on the galvanized coating but the fact that all cars started using it about the same time period Porsche did so you will run into this with just about any make of vehicle.

[3 pedals]

Thanks 962 Porsche for the info. Can I buy the wipe/cleaner at a store like PPG as well as the epoxy primer? Kip

[962porsche]

you can buy the products you need for any number of the automotive body supply stores.
I would recommend you pick a product line and stay with all the products in that product line. so if your going to go with PPG than only use PPG products.

[Bill Douglas]

Haha, whatever you do, do what 962 says. He is SO correct in all of his advice.

We are lucky to have him giving out great advice.

[Otter74]

This seems like a good thread on which to piggyback another question for 962porsche - what primer should be used in a case where the car will go some time before it gets a color coat, including being driven? My Fiat Spider is finally getting a body restoration and my budget for the year allows for everything up to final paint but almost certainly not that. In the meantime I'll do all the deferred mechanical maintenance and finish the bodywork next year, driving it later this year in the meantime. I'm sure the shop that is doing it knows this, but I'd like to know for myself.

[Dpmulvan]

Originally Posted by Otter74

This seems like a good thread on which to piggyback another question for 962porsche - what primer should be used in a case where the car will go some time before it gets a color coat, including being driven? My Fiat Spider is finally getting a body restoration and my budget for the year allows for everything up to final paint but almost certainly not that. In the meantime I'll do all the deferred mechanical maintenance and finish the bodywork next year, driving it later this year in the meantime. I'm sure the shop that is doing it knows this, but I'd like to know for myself.

You don’t want to drive a car with just primer on it. Primers are not formulated to be exposed to the elements/ water et.

[Otter74]

Originally Posted by Dpmulvan

You don’t want to drive a car with just primer on it. Primers are not formulated to be exposed to the elements/ water et.

I had assumed as much, but didn't know (since I am not very knowledgeable on paint) whether there was a thin coat of something that could be sprayed on top of it in the interim and sanded down when the car is prepped for final color. If the car gets driven (I'd certainly like to), it won't be in wet conditions.

[962porsche]

it's not even a good idea to let a car sit inside for as long as your talking about with just primer on it. moisture even simple humidity goes right thru primers. the only protection against rust protection is the top coat AKA paint /single stage color coat or clear.
primers are designed for adhesion not protection.

[Otter74]

Thanks for chiming in - is there anything short of applying the color coat that will mitigate the downside?

[962porsche]

no !!!!!!
paint AKA top coat is what protects the metal.