Painted Surface Rust Advice

[Dyn Blin]

Good evening all- I'm looking to the wisdom of the collective on this-

'Prior owner stored my truck just off the east bay, prone to salt fogs and winds. The truck is generally rust-free, but I've noticed surface rust in some areas, so I'm trying be preventive before it can get a foothold.

I spent part of the weekend getting the chrome shiny again, and removed the bumpers- taking the rust off the back of the bumpers with naval jelly, thoroughly rinsing and neutralizing with sodium bicarbonate, and sealing with a coat of POR-15.

As I moved on to remove the door panels to repair rod linkages in the door frame and locks, I noted the inside of the door skins have a very light coat of rust on the "orange peel" surface of the paint.  I'm presuming this has been exacerbated by missing door glass runs, channels and lower seals.  I'm also presuming any rust, no matter how light, means it has made it past the thin paint layer.

What recommendations would the group have to tackle this "right"?  Stripping the paint before using the naval jelly? Or, will the naval jelly take off enough of the painted surface with the rust?  Or, what are other recommended processes & products have worked for you?  

[Gary Lewis]

POR-15 actually adheres better to rust than it does bare metal.  You need to remove flaking rust and any grease or dust, but you can paint it right over the rust and it is supposed to kill it.  So, you could coat the inside of your doors with it and that should stop the rust.

[Dyn Blin]

Not the answer I expected, & great news Gary, thanks.  

That should save me a good amount of time.

[Gary Lewis]

From the instructions:

Surface preparation: Rusted surfaces are best; seasoned metal and sandblasted surfaces are also good.
SANDBLASTED SURFACES; Apply POR15 Rust Preventive Paint directly to the sandblasted surface.
SEASONED OR RUSTED METAL: First, wire brush loose rust and scale. Then remove any grease or oil with POR15 Marine Clean and prep with POR15 Metal Ready, leave Metal Ready wet on the surface for 20-30 minutes, then wash off with water. Dry the surface completely. Failure to do this may trap moisture under the paint and rust will form again.

[PetesPonies]

Not  a fan of POR at all. And my business name has RUSToration in it  :) Simply, don't use it over bare metal, period. If you want a material to use, use Master Series silver. If you want to know why, google PetesPonies and Master Series. I think I have written a book on it. Treat rust like this . . .remove all paint. mechanically remove rust. Use a DA, if on sheet metal to be painted. use 80 grit or more coarse. After that, apply Phosphoric acid. Keep it wet, use a scotch pad to work it around. Keep it wet, don't let it dry. When you are satisfied, remove it with clean paper towels. No water, I don't care what the instructions say. Again, google PetesPonies, phosphoric acid, and DuPont to find out why. Then spray ( or brush depending on where it is ) Master Series silver. At least two coats. YOu can wait for it to tack up and spray epoxy right over that. Or, let it cure, scuff it , then apply epoxy. Once the epoxy is down, treat it just as you would any other metal. You will NOT have any more problems for that area, promise.

[Dyn Blin]

Thanks Pete, that was a a deep and educational rabbit hole returned in the search results.  I just ordered a quart of the Master Series Silver and will give it a try according to your instructions.

[PetesPonies]

I've been doing this for a long time with good results  :)

[PetesPonies]

I use it on every welded seam as well. If I can get to the backside, the weld is sandwiched in Master Series.

[FuzzFace2]

PetesPonies wrote

I use it on every welded seam as well. If I can get to the backside, the weld is sandwiched in Master Series.

Little late to this party but got a question.
You can weld thru the silver master series like weld thru primer?
If so I may have to look into it.
Dave ----

[PetesPonies]

No, and weld through primer is a misnomer. Everything burns. It's supposed to seal back up afterwards, BS. I never use the stuff, it's pure BS. And I taught welding for a long time :)  I seal the welds after welding, before any filler or epoxy.

[FuzzFace2]

Looking closer at the picture of the inner wheel well it looks like you only used it on the area above the lip and not where the outer skin & inner meet and would be spot welded right?

As for the weld thru yea it will burn thru but my thinking is all around that area will have a coating the rust would have to get thru so hope to slow rust down a little.
Dave ----

[PetesPonies]

That's where I used it in that situation yes. But it can go everywhere you want it to go.
This entire cab has been primed with Master Series.