Surface rust repair - best method?

[thomasando]

My 80 used to be a workhorse in a previous life, and had a 'tradesmans' roofrack (that is both ends open to carry long objects). My guess is as a result of carrying something-or-other up top, the paint has been scratched away in a few places on the roof. It looks like it's only surface rust as it appears to be fairly recent, and only present in the actual scratched areas.

What's the best way to repair this? Should I grab some fine grit sand paper, sand it back until the rust is gone, and paint over it with spray paint?

Looking forward to the advise on offer!

 

[IdahoDoug]

Rust only continues to grow and damage metal when it has oxygen. Many people go crazy on rust areas on cars and feel they must cut it out and replace it because it's "like cancer", etc. It's not like cancer - won't grow if it's coated with paint. I've watched with dismay as this mistaken belief has led people to cut out sheet metal with a bit of rust far beyond what is needed.

If these are thin deep scratches, I would simply rub in the direction of the scratch with a terry rag to remove the loose stuff - perhaps with some rubbing alcohol on the last bit of rubbing to ensure adhesion. Then fill with a Toyota touch up paint bottle - the type with a brush built in.

Don't go nuts and try to sand the area down and respray. It would take an expert to make that look good.

DougM

 

[thomasando]

Thanks Doug. I'll have to track down a bottle of touch up paint. Most of the scratches are thin and not very deep, but there's a few there that are fairly deep as well.

 

[Tools R Us]

I prefer to kill the rust before painting. By using phosphoric acid the rust is converted to black oxide (like on impact sockets) and will not grow. The process is simple, tape off where you don't want it, wipe it on, allow time for it to work, rinse, dry and paint.

The product that I have is SEM Rust-Mort, have also used Jasco Metal Etch and Prep & Primer all good stuff, that are available at hardware and paint stores.

http://www.jasco-help.com/products/prod_mg.htm

http://www.sem.ws/product.php?product_id=164

 

[jamisobe]

I prefer to kill the rust before painting. By using phosphoric acid the rust is converted to black oxide (like on impact sockets) and will not grow. The process is simple, tape off where you don't want it, wipe it on, allow time for it to work, rinse, dry and paint.

The product that I have is SEM Rust-Mort, have also used Jasco Metal Etch and Prep & Primer all good stuff, that are available at hardware and paint stores.

http://www.jasco-help.com/products/prod_mg.htm

http://www.sem.ws/product.php?product_id=164

X2. I have success with Rustoleum Rust Reformer available at the hardware store.

 

[super90]

I did exactly what Doug described but before I painted I used a bit of phosphoric acid to neutralize any oxidation there. A little extra insurance.

R.

 

[C6H12O6]

I'd dip the whole truck in thinner and coat it it POR-15, followed by Line-X.

Seriously, I'm sorta with Doug on this one. The people who run into trouble with rust bubbling back up from under the paint usually didn't really seal the rust off. If you do a good job with prepping the area and get good coverage with whatever touch-up method you choose, you shouldn't have a problem.

Rust needs oxygen. If you cut that off, it maybe doesn't die, but at least goes dormant. One major exception is rust that goes through to the backside. If the metal is rusted through, you need to take care of both sides, or cut it out completely. Probably not an issue in this case.

 

[RavenTai]

If these are thin deep scratches, I would simply rub in the direction of the scratch with a terry rag to remove the loose stuff - perhaps with some rubbing alcohol on the last bit of rubbing to ensure adhesion. Then fill with a Toyota touch up paint bottle - the type with a brush built in.

Don't go nuts and try to sand the area down and respray.

Who are you and what did you do with Doug!
























sorry just seams out of character


I would sand it down, phosphoric treat, tape off, prime, then paint. it will not look as good as Doug's way but I would feel better about it, I have 4 rattle can patches (roof rack feet) on my roof, they do not look good on close inspection but they are not noticeable up there

 

[Skillet]

I have used a product called Navel Jelly. Probably the same thing as the rest but it worked well for my 40 in some problem areas.

I also used it on the bottom of my gun safe, worked well.

It turns the present rust into a black, paintable surface.

My $.02

 

[AJP]

"Naval Jelly" worked well for me too...had some rust coming up on the front bumper ... after repeated attempts at sanding/wire brush/priming and touch-up...it would return in a few weeks. Last time I did this I brushed Naval Jelly on the sanded bare metal ... left it 10 minutes...washed it off with warm water.. dried..primed & touched up...and no recurrence. This seems to do the trick in "killing" the oxidation process so you can seal the metal off properly...

 

[IdahoDoug]

Raven,

Yeah, it's not the usual OCD solution - heh. But I restored several cars and was part of that community decades ago in Michigan - a rustbelt state. A scratch can be made to look quite good with a steady hand, and if it's also followed up with a bit of clearcoat it is a permanent solution. It was always a pet peeve of mine to watch with dismay as people mistakenly believed the presence of a little rust meant that particular area of the sheetmetal was contaminated as though it were a bacteria. They'd go nuts cutting out chunks of perfectly fine sheetmetal rather than cleaning and sealing a minor blip.

I like the solutions to neutralize before painting, BTW.

DougM

 

[RavenTai]

I certainly agree that no need to start cutting for surface rust that has not gone all the way through yet. a metal patch is certainly more prone to corrosion than properly dispatched surface rust, especially if you do not have good access to the back side to properly seal it.