Rustproofing

[Sureshot324]

My car has quite a but of surface rust on the bottom, though nothing's rusted through yet. I asked my local garage about rust proofing, and they said they basically just spray it over top of everything. They don't clean the rust off or anything.

Is this ok? It seems to me that the rust should be sanded off first so it doesn't spread.

 

[imported_Imp]

Sounds like a half-assed job. You could argue that rust is a protective layer in itself, but since it's an uneven/porous surface, it probably will spread. Not to mention since rust is so brittle, once the stuff comes off, it'll take the rust proofing with it.

 

[jlee]

What type of rust-proofing? There's some stuff that you're supposed to put on over rust (after you knock the loose stuff off), which basically solidifies and hardens into..something. I've never used it, though.

 

[JulesMaximus]

If your goal is to mask the appearance of rust and to have it eat away the metal underneath then yeah, I'd say go ahead and just spray over the rust.

The only way to get rid of rust is to remove it down to bare metal. Then you fill, prime, paint, and clear coat over it.

 

[thedarkwolf]

Originally posted by: JLee
What type of rust-proofing? There's some stuff that you're supposed to put on over rust (after you knock the loose stuff off), which basically solidifies and hardens into..something. I've never used it, though.

There are several but POR-15 is the one most people think of. I used it all over the place under my old 67 ford galaxie. Its one of those products that really does live up to the hype.

 

[brblx]

por-15 is pretty damn great, but it's meant to seal and to some effect neutralize rust. i did a rusty trunk pan years ago and it's still fine.

undercoating might have a similar effect, but sooner or later (probably sooner) oxygen and moisture are going to get under it and continue to feed the rust.

 

[Pacfanweb]

POR is a rust ENCAPSULATOR. It does not chemically react and neutralize rust, it seals it off from moisture so it can't rust anymore.

You aren't supposed to just paint it right over a ton of rust, you're supposed to at least wire-brush it first. But it's fine to leave some rust on there, that's what the POR (Paint Over Rust) grabs onto.
Another brand I can think of that does essentially the same thing is Eastwood Rust Encapsulator. Good stuff, too.

Now, there are other actual rust killers, or converters, like Rust-Mort. They react with the rust, and turn it to a paintable surface. You also want to at least wire-brush that off, then paint right over the rust. These products usually turn the rust black.

Eastwood has both a rust converter AND an encapsulator product.

 

[SparkyJJO]

Originally posted by: Pacfanweb
POR is a rust ENCAPSULATOR. It does not chemically react and neutralize rust, it seals it off from moisture so it can't rust anymore.

You aren't supposed to just paint it right over a ton of rust, you're supposed to at least wire-brush it first. But it's fine to leave some rust on there, that's what the POR (Paint Over Rust) grabs onto.
Another brand I can think of that does essentially the same thing is Eastwood Rust Encapsulator. Good stuff, too.

Now, there are other actual rust killers, or converters, like Rust-Mort. They react with the rust, and turn it to a paintable surface. You also want to at least wire-brush that off, then paint right over the rust. These products usually turn the rust black.

Eastwood has both a rust converter AND an encapsulator product.

I should use something like that on the underside of my car. It could use it before the rust gets out of hand.

 

[brblx]

Originally posted by: Pacfanweb
POR is a rust ENCAPSULATOR. It does not chemically react and neutralize rust, it seals it off from moisture so it can't rust anymore.

You aren't supposed to just paint it right over a ton of rust, you're supposed to at least wire-brush it first. But it's fine to leave some rust on there, that's what the POR (Paint Over Rust) grabs onto.
Another brand I can think of that does essentially the same thing is Eastwood Rust Encapsulator. Good stuff, too.

Now, there are other actual rust killers, or converters, like Rust-Mort. They react with the rust, and turn it to a paintable surface. You also want to at least wire-brush that off, then paint right over the rust. These products usually turn the rust black.

Eastwood has both a rust converter AND an encapsulator product.

por-15 sells a spray solution that they recommend with the paint, that's what i'm referring to as far as neutralizing. yes, if you just use the paint, it's still a really good sealer. and yeah, of course you want to get the scale off it, first, if present (the rust is pretty damned bad if so), but just painting straight over surface rust works fine.

 

[CurseTheSky]

Hmm, this is a subject I've been interested in too, for my Mustang.

Is there anything that works well on shiny metal to prevent rust? I was going to just undercoat everything, but I really don't want to find classic car cancer all over the floor pans, wheel wells, etc. 5-10 years from now. Now I'm thinking of doing a quick primer / enamel (Rustoleum, probably) with rattle cans, then spraying undercoating over that. I know a lot of people that swear by POR-15, but I've heard it doesn't stick well to shiny new metal.

Any thoughts?

 

[ballmode]

I need to paint haha