View Full Version : Stablizing rust on sheet metal parts

11-15-2008, 06:05 PM
I did a search before posting and did not find anything in the Paint forum. So here's my question. I am resurrecting an original paint '47 Knuck in Skyway blue. Today I pulled the taillight and fender light off to find nasty rust from moisture collection under the light gaskets. The paint is excellent around the light gasket, except for some rust invasion just around the edge of the gaskets. I'd like to stabilize this rust with one of the products on the market like POR 15, Rustoleum, or Extend. On the rear fender, the rust continues into the tailight wiring looms that are spot welded to the rear fender. So I plan on rigging a swab up so I can drag whatever I use thru the looms to stabilize any rust in those areas.

It's amazing how good the underside of the fender looks compared to what I found under those lights. The taillight area is the worst of the two.

I'm looking for recommendations or warnings basedo on personal experience and not second or third hand info.


11-15-2008, 07:29 PM
I have used Extend for the reason you mention. Apply it carefully as it will be noticable after dry, the rust will turn an ugly black and it will look kinda like dried elmers glue over top of paint or chrome. I haven't tried it over parkerizing but I imagine a similar effect. I have used it mainly for rust at the welds on chrome plated parts , applied very carefully with a Q-tip. Seems to last about ten years or so in regular service.

11-15-2008, 07:58 PM
Thanks for the quick feedback Brian. I used Extend many years ago and it's precursor, Trustan, which had the chemicals that stabilized the rust but without the polymers that make it more like clear paint. I had pretty good luck with it. The new POR 15 products seem to get rave reviews, but I'd like to hear more before I start to slap it on my knuck. The POR 15 products offer a clear, that just might keep the rust looking like rust while killing it's spread.

No Extend in my local hardware store. I looked for it tonight while doing a load of shop towels in the local laundromat. Pretty sure Lowes or Cheapo Depot sells it.


40 Nuck
11-16-2008, 08:13 AM
Haven't used the POR product, but really like the Extend. I've actually thought that it looks a bit like a near-black parkerizing. You probably already know this, but since the rust is mostly hidden, I would suggest taking off any heavy rust/crustiness before applying the Extend. Getting it as close to "surface rust" as possible, will allow the extend to penetrate better. I've used extend on cast iron that is in the weather, and gotten about three years of life out of it even sitting in the rain as long as I wire-brushed it down before-hand. Also, FYI, the first person that recommended it to me was an old chemist that worked for an industrial paints and coatings firm.

11-16-2008, 11:56 AM
That's right. Extend is not a rust remover. You still have to get the metal as clean as you can. I really like the stuff. I like to pour it into places I can't get to, like the inside of handlebars, etc. But I still think of it as just a surface prep, to be coated with something else. I also like the Klean Strip "rust converter". You can discolor stuff with it, so be careful. Thankfully, it just polishes off of chrome easily.