Rust prevention

[cruiksdr]

I've seen a number of excellent discussions here on this and on painting in general, but I am unclear about one thing.

If I use POR15 or a similar product on all of my bare metal to stop any new rust from forming and to kill any residual, can I then spray over the por 15 with primer and final color? It looks like some people are using por15 just in places that will not be seen (trunks and floor pans) but not other metal surfaces like fenders, etc. But some have alluded to top coating. But on discussions about paint, everyone seems to agree that all the paint materials should be matched by manufacturer. I'm confused. I'm getting ready to do my car, and I don't want to see any rust bubble up under the paint down the road. I'm going to preserve as much as possible the factory finish as a base, but there are places that will need to be stripped to bare metal. Can I treat these with por15 and then top coat? If not, then what is should I do here?
I've seen a number of excellent discussions here on this and on painting in general, but I am unclear about one thing.

If I use POR15 or a similar product on all of my bare metal to stop any new rust from forming and to kill any residual, can I then spray over the por 15 with primer and final color? It looks like some people are using por15 just in places that will not be seen (trunks and floor pans) but not other metal surfaces like fenders, etc. But some have alluded to top coating. But on discussions about paint, everyone seems to agree that all the paint materials should be matched by manufacturer. I'm confused. I'm getting ready to do my car, and I don't want to see any rust bubble up under the paint down the road. I'm going to preserve as much as possible the factory finish as a base, but there are places that will need to be stripped to bare metal. Can I treat these with por15 and then top coat? If not, then what is should I do here?

[dtw]

POR-15 is a great coating for wheel wells, cavities, etc. I personally would NOT use it as a base for "finished" panels such as quarters and fenders. I've read all Restomotive's documentation and talked to them about doing this. It is possible to do it 'on paper'; they sell their Tie-Coat primer which is definitely a great intermediate coat between POR15 and conventional topcoats. I've used this approach with success on frame bits and suspension pieces.

There are characteristics of POR15 that make it a sketchy proposition for underlying finished outer panels
-Spray characteristics are difficult to control; it goes on thick and runs easily
-It doesn't sand out - not even a little bit.

Thick coats are not really desireable for nice paint jobs, and sandability is a must-have characteristic. If you properly prepare your metal and use epoxy primer, you should have no rust problems at all. Epoxy primer is the choice of the DIY painter anyway - it is the only conventional basecoat (not talking about POR anymore) that does not absorb ambient moisture, destroying the paint.

Keep in mind that the POR is fine for other panels, though. I sprayed POR-15 on my entire front clip after stripping it to bare metal. I shot rubberized undercoat directly on the 2nd coat of POR15 with outstanding results.

There is an interesting counterpoint to the above, though. Jamie Novak has actually painted his entire car using Restomotive Labs products - he likes their Stirling Silver product so much, that he did his final paint job with that and their clearcoat product. The results so far are good, and the long term will tell how his unique idea works out. Note that his goal for the car is to have a good street/track car; show-quality paint was not the objective. I'm pretty sure he'll chime in on this thread in the morning.