Repainting an old rusty trailer frame.

[Tearsthuseist]

I have been in the process of angle grinding away all the thick layers of paint and rust off an old trailer frame I recently bought. There was kind of a lot of both on this particular frame. Some of the frame is slightly pitted from the rust, but all in all its in pretty decent shape, however I haven't started on the underside yet, it might be worse under.

I've been doing some research on the best way to prime and re~paint it. Some things I've read that people do is simply put on Rust~olium's Rust Reformer and spray on truck bed liner rubber over the top. However, on the car restoration sites, I've read about a special primer called etch primer ~ Dupont Variprime. It goes on bare metal and I understand it chemically bonds to the first few layers of the metal. Sounds great but it's very expensive and a quart supposedly cost around $60.00 and up, plus it's difficult to find a place to get the stuff at.

I'm in a tricky spot because It's the rainy season here... I'm doing this frame grinding outside, and the whole top is finished, and is under a tarp. I feel like I should put something over the bare metal now, before it rains again, and before I flip over the whole frame and commence work on the underside.... Supposedly no rain till Sunday.

Anyone have had any experience with Variprime? Or, any other technique that really works. What's the group's consensus as the best way to paint and keep new rust away at the same time??



Here is the worst of the rust damage so far after grinding... I dunno, no holes thru, but maybe I should reinforce that.

[KCStudly]

Yeah, that last bit looks a bit too far gone. Cut out one side and weld in some flat bar, or just scab on a piece if you can make the extra thickness work easily with the fit of your floor to the trailer. The longer more tedious option would be to try and weld all of the pits up and then grind back close to smooth, but you would risk blowing through, and heat warp issues.

When you say you are using a grinder do you mean with a flap sanding disk or a hard stone? Be careful not to take away good metal. Use a wire wheel or cup to get the rust out of the pits without taking excess metal.

POR 15 rust encapsulating paint worked really well after power wire brushing my car trailer frame. It had sat out in the weather, including several years of snowy winters, incomplete and raw steel, unprotected. Use the UV blocking top coat, also available from POR. Not cheap, but well worth it.

I would do the whole thing with the wire wheel before paint.

Good luck in your build. You have a good start.

[Dale M.]

I would not mix products... IF you decide to use say, Rustoleum products, I would use appropriate rust encapsulation primer and then top coat..... Putting bed line on something and then getting moisture under it will just breed more failure (rust).... Also bed liner is miserable to clean off if you have to do any welding repairs....

I painted a new steel trailer frame with Rustoleum (regular ) primer with a brush (yes a brush) and put a top coat of semigloss black over it, it sat in storage for about 3 years and now has set outside almost 4 years, and it has not rusted yet!...

Love Rustoleum products you just have to have reasonably clean base to apply it to...

Dale

[Tearsthuseist]

@KC~ Yes I've been mainly using a wire cup brush on the grinder, I also have been using a flap sanding disk for stubborn spots, but even used a stone grinder where a few screw heads broke off as I tried to get the last few out of the frame.

By the way I found a few spots with little rust holes all the way thru. Definitely will need to be fixed. I own an Oxy/Ace set up... However I have a friend who's licenced as a welder, and I'm certain there's better ways to fix those spots than with Oxy/Ace... He said to drive it up to his shop when I'm ready, tons of scrap around his shop he said I could use for free.. Bad part is that he's about an hour and a half drive from here, better get the temporary tag ready.

@Dale ~ Yea, I ended up using Rustolium Rust reformer over the whole top, and plan and doing a few coats of flat black Rustolium, probably also brushed on because the previous owner of the trailer gave me a new quart of the stuff. I might as well use it... Probably thicker coats instead of spraying anyway. I would've liked to wait and sand the entire frame before I started painting it, but it's going to rain over the next few days. I don't have a garage so, I'll have to do it in sections.

[amelia]

Try to rent or borrow a sand blast attachment on a pressure washer. That will shift any corrosion. Then you can feather the edges of the surrounding sound paint whichever way you prefer.

[Super Dave]

I also recommend POR15.com as I used it on the frame of my camper. You have to follow the steps they tell you to do in order for the paint to adhere properly but results are well worth it. As a added bonus, the paint actually is cured by the moisture in the atmosphere and is tuff as nails when done. As long as it is not exposed to sunlight on a permanent basis you don't need to topcoat it. It's not cheap but you'll only have to do it once

[asianflava]

I used www.rustbullet.com it was a one step process with a foam roller.

[48Rob]

To those who have used these different paints/coatings designed for rusty metal; how many years have they lasted before rust showed up again?
And; do they act like powder coated metal, where rust starts unseen and eats away at the steel until the powder coat can no longer "hide it" and it falls off in chunks, exposing the rot?

Rob

[KCStudly]

Must be at least 4 years since my car trailer was coated with POR15 and the matching top coat. There is a little bit of green mold or moss growing on it. It sits under trees that dump their leaves and I don't get out there often enough to clear them off. It has seen at least 8 ft of combined snow fall in the last 2 -3 years alone, and the leaves and dirt under it hold moisture. I see no signs of any breakdown in the paint whatsoever. I am convinced that the metal will rust out from the inside before the paint breaks down.

Now, if I were to actually use the trailer and perhaps abrade the paint around the tie down points by dragging chains and the load ramps over the paint there might be some local damage, but it is pretty tough stuff.

[48Rob]

Thanks KC,

My real concern is that the very tough finish forms a "skin" that conceals continuing rust/rot under that skin, hidden from view until the damage is so severe it can not be repaired, or causes a structural failure.

Of course if you get 100% coverage, it is 100% protected, but if it gets a nick or scratch, and moisture gets in, is it (damage, rust streaks, bubbling, etc.) visible so you can make repairs to the top coating?

Rob

[High Desert]

Rob, the POR15 product goes on basically water thin. It is designed as a rust inhibitor and penetrates into the rusted areas. They say the oxidation action of the rust wicks it in. I've used it on old cars around fenders and other rust prone areas. You can also apply it with fiberglass mesh, which will cure hard as a rock. I rebuilt a partially rusted through battery tray using the mesh as an experiment to see if it was as good as they claimed. Reinstalled it in a daily driver. That was 5 years ago now, it's still solid. Pretty good stuff in the proper application. Paint over it and you can have a relatively permanent repair.

[KCStudly]

Not sure how it does with poor prep, but over power wire brushed steel, wiped down properly, like what the OP has shown, it will bite right in and you're good to go.

It’s not going to solve flaky rust, but it will encapsulate minor pits and areas that the wire brush can't get 100%. All in all it is certainly better than rattle can primer and paint, IMO. And for my money it was worth the added cost (even if I had paid for the base coat... I bought the top coat and used the money I saved on the donated base coat to pay Karl's helper to help with the wire brushing).

[48Rob]

Thanks guys,

I don't have a seriously rusty frame.
The frame I need to paint is a mix of old and new steel, that has a little surface rust here and there (no pits, nothing scaley) that will be at least wire brushed if not media blasted.
I bought some epoxy primer that the local steel yard uses on everything they send out, but asked about the other options in case they were a better bet.

Rob

[Super Dave]

POR15 states that even if you manage to scratch through the paint only the exposed metal will rust and it will not crawl under the surface and lift the paint. If you do right the first time with this product you'll never have to do it again.