Primer for Rust-prone Spots?

[ammodram]

Guys -

I'm going to have a friend repaint the fenders from my Kubota L245DT.

The undersides of these fenders are really prone to rust, and they are getting hard to find replacements for. I want them to stay intact!

Is there a good rust-inhibiting primer I should have him use after he gets them cleaned up?

I was planning for the top coat to be the "old" color of Kubota OEM orange, but I don't know what to use on the bare metal first.

Thanks!
Matt

 

[Slacker]

I used "rubberized" undercoating on several jeep frames and they are looking great after 5 years. It's cheap spray bomb cans at the auto parts stores.

 

[ray66v]

Tractor Manufacturers are often guilty of using single step direct to metal paints, that do not protect metal well, leading to the situation you are experiencing.

I have tested every possible way of stopping corrosion repeatedly over the last 30 years in the Auto Body business.

There are many good primers avaliable today. However, they can be expensive.

A good primer will be able to self etch, (create a chemical bond), and have a strong high density, low porosity film. This film will protect the metal from moisture penetration and thus limit corrosion. If You Have a Sherwin Williams Automotive Store in your area I recommend NP75, (does everything including fill), although I am not sure if it comes in quarts.

Though some products out there are single component, (all in one can), and claim to be all the above, they are simply inferior. Only the 2 component primers are able to do everything well. Plan to spend in excess of $100 for a quart of primer and activator, at your local Auto Body supplier. They all make similar products, just make sure it is a direct to metal primer.

In lieu of that, you could probably do ok, after careful removal of rust in the affected areas, with a Rustoleum, or similar, primer, and some type of topcoat.

The rubberized undercoating from spray cans, mentioned in a previous post, is a cheap way to form a self adhering barrier, and is often used as such. However, I personally have not found this to be an effective way to really protect things. It is more suited as a way to hide corrosion. The barrier these products create, unlike professional undercoating, can be porous. This can lead to reoccourance, with the big problem now being the surface is covered with undercoating. Now you will have to remove the undercoating, (bigger mess), to treat the corrosion. NEVER paint over undercoating.

 

[swines]

I've had good results using Eastwood Company's two step process using the rust converter on rusted areas followed up by the rust encapsulator, and then final paint.

Eastwood Company: Search Results for rust

 

[ray66v]

I've had good results using Eastwood Company's two step process using the rust converter on rusted areas followed up by the rust encapsulator, and then final paint.

I have not used the Eastwood products, How long can you say it has worked for you? We tested similar products many years ago, on chain link fence posts, and found they did work, but, only about a year or so. I would think they have gotten better since then.

I have used a similar products to the fast etch they sell, it should work very well under most basic primers to give a good bond.

Both could be a good solution for rust you can't get to.

Since you can't always get a quality finish painting over some of these products, they should be tested, through trials to determine if they will cause shrinking or swelling with the particular top coats you want to use. Unless that is not an issue.

 

[RalphVa]

I'd use Rustoleum's Rust Reformer or NAPA's Trustan (think this is what it's called). These react with iron oxide (rust) and convert it chemically to a hard, black iron sulfide.

Ralph

 

[dqdave1]

You may want to try POR 15; look on ebay. people swear by this stuff.

 

[john_bud]

Dupont Corlar 2.1 PR. It's a 2 stage industrial primer and is hard as nails. It is a pure pain to work with if you are using garage equipment, but if your buddy has pro equipment, it's not too bad. The finish will look "hammered" and not flow out smooth, but for the underside - who cares?

PPG has an equivalent product.

Both REQUIRE supplied air respirators.

jb

 

[Skyco]

I like the cold galvanizing zinc rich paint for things that may rust. That stuff works great and even if chipped it will sacrifice around the chip so the chipped area still doesn't rust.

RustOleum.com

The stuff is real bad about clogging up the spray nozzle after use so be sure to do the upside down spray until just gas routine.

 

[sunspot]

I remember reading about primers on YT. There was a guy there that sweared by using a Phosphoric acid product. He said it blackened the metal sorta like gun bluing.
Anyone know of any products like that?