Rust: Rust coverter srpay instead of sand/prime/paint?

[JEDI]

2005 mazda 3i, 180k miles

I have a little rust around the bottom edge of my rear wheel well, about 3" in length.

I was going to sand that small area, apply primer, then use touch up paint.

then I read about rust converters:
http://www.wikihow.com/Remove-Rust-from-a-Car
"Unlike the standard scrape, prime, and paint regime, the user does not have to bring the surface down to bare metal. "

just spray on affected area. the spray will convert the rust into iron tannate.
$3 at walmart. then use touch up paint, which I already have (size of nail polish remover).

What do you say ATOT mechanics?

 

[Tweak155]

I have a 2003 Expedition with some rust starting on the bottom inside of the doors. This would be awesome if it actually worked...

 

[jumpncrash]

It does work to a certain extent, however the rust underneath what it converts will continue. I usually use a 2 step approach. Mechanical removal with a wire wheel/brush and then I rust convert that area.

 

[thedarkwolf]

I've used Por 15 and Navel Jelly and had better luck with Por 15, might just have been the Navel Jelly was on much MUCH worse rust. Still have to knock off the loose stuff.

 

[monkeydelmagico]

If you can get down to bare metal and get rid of the rust completely then sand prime paint is the way to go. If you can't, like on closed panels or ones you cant cut and weld, then wire brush and naval jelly are a good way to slow down the cancer.

 

[CurseTheSky]

As others have said, rust converters only chemically convert the top layer. Rust will continue underneath or from the other side of the panel. It will slow down the progress, but it won't stop it. It also won't look pretty, as it (IIRC) converts rust to a black oxide that is more stable than standard red rust. Probably Fe2O3 -> Fe3O4. It'll look poor on the outside of a car, so I'd limit usage to the underbody, panels hidden from sight, or on a vehicle that you don't care about the looks of.

Your best bet is still to sand, fill, sand, prime, and paint. Always extend out from the rusted area by a little bit (at least a centimeter) to ensure that you got it all.

 

[sontakke]

Mazda? Rust?? Who would have thought

Seriously, I have no idea what Mazda puts in their metal but they start rusting prematurely.

 

[Pacfanweb]

Converters DO work. However, you still need to brush/grind/scrape as much rust off as possible first.

Get it down to bare metal and the pitting, THEN use a converter, and the rust is dead.

 

[Tweak155]

Mazda? Rust?? Who would have thought

Seriously, I have no idea what Mazda puts in their metal but they start rusting prematurely.

I just recently saw a 2006 Mazda 3 with rust that went all the way through, thought it was pretty odd on a 7-8 year old vehicle.