Bare metal epoxy primer for truck frame

[Hay Dude]

I am certified on a number of automotive manufacturers paint systems. NONE of them have, use, require or recommend a rust converter in their best practices. That should tell you something.

If you are not going to properly clean the metal for paint, it's a waste of time painting it. Rust converter is a gimmick for homeowners to use when they can't, or won't properly prepare the metal. If you remove the rust, there is nothing to convert.

Preparing that frame for paint while it's on the truck will be all but impossible.

The rust needs oxygen to form. If you cover the metal with anything that blocks the air and water from it, it's going to prevent corrosion.

I suggest you scrape and wire wheel it thoroughly, them apply a coat of a professional quality undercoating: Rusfree ruberized undercoating, which you can brush, or spray on, https://a.co/d/7hjbILp That will actually do more to protect it than anything you can do yourself. While it's a dirty job, it's very cost effective. It does dry enough to touch it without transfer, but will never crack, or flake off if the surface is clean when applied.

Just read a bunch of actual user testimony and write ups on rusfree. Looks promising.
A few recommended rust converter first, then apply rusfree.

I am kind of feeling overwhelmed with different tactics and products to do this.

Would the rusfree look like black paint enough when done to look good? If the frame is black and preserved, mission accomplished. Truck isnt a show piece. Longevity is the goal.

 

[dstig1]

The Chemists I have worked directly with in product development, and testing consider them all the same, and don't classify the primers with or without, in different categories. They say the "epoxy" aspect as a marketing gimmick, and it's all the same.

If "epoxy" primers were truly better, they wouldn't be making them without it. Most don't have it, regaurdless of cost.

I can further tell you I have used all sorts of products, in every possible application, over decades, and have found no discernible difference between products that use the term "epoxy" on the label and those that don't. They apply, and react exactly the same way.

Then if that is the case, they are mislabeling it as epoxy. It is a specific chemical family.

Epoxy - Wikipedia

en.wikipedia.org

Again, no opinion on whether or not it is the right stuff, just keeping terms straight.

 

[alexpops]

If Iwas looking for protection vs looks, I'd go ahead & blast/wirewheel/scuff pad everything reachable to eliminate loose scale. Then, I'd use a pump bug sprayer to spray the frame down with ospho/etch &prep or any other phosphoric acid I can find, paying attention to any internal surfaces i wasn't able to blast/grind. I'd spray 2 or 3 times to make sure everything got at least 1 shot of acid. It'll convert iron oxide to iron phosphate, and It'll etch the bare metal. Once dry, I'd powerwash to get rid of residue/ neutralize. Let the water dry. Then I'd spray the external surfaces with a good two part primer that's compatible with whatever you are top coating with. The internal surfaces aren't going to get decent paint coverage unless dipped, so I'd just hit them with a lanolin type or oil cover. The problem with the rubber coatings is that when they fail, they trap moisture salt etc., and start the rusting all over. I'd topcoat the external frame surfaces with a decent hard paint, or if i had extra cash & trusted the shop doing the spraying to do good prep, linex. Final step would be lanolyn type coating (fluid film/woolwax/surface shield) over everything with a plan to renew every year. Or ... skip the primer/ topcoat & run surface shield, fluid film, woolwax after pressure washing the ospho.

 

[Hay Dude]

Will Linex stick on and stay there? Or will it peel, chip soon?

 

[alexpops]

All depends on the prep. Linex is a polyurethane/polyurea, so in theory, it should work/stick forever on a good base. They give a no lift/no peel guarantee on bed liners. You want no oil/grease/wax, a solid base, and enough "tooth" for it to stick. If you have a shop near you, take the truck for a quote & ask the sprayer what prep would be needed/recommended to give you best results. Specifically ask about primer type as they may want polyurethane primer instead of epoxy. I'm guessing you could do 90% and they would need to scuff/degrease to be able to honor a warranty. I've done beds and inner fenders/wheel wells with great results, but never a frame.

 

[Hay Dude]

I have to come up with a plan in a few days.

Sandblast is of course the first step.
I think I’m sold on the Rust Kutter rust converter.

After that?

The shop thats doing the sandblasting offered rhino-liner type coating or prime/paint.

I want something black that will really stick without breaking the bank

 

[mrmikey]

.....offered rhino-liner type coating or prime/paint.

Only thing I don't like about your plan. I'd be scared that the liner is going to trap water in areas that are prone to water wicking. Cross member ends for example, wherever there's two surfaces fastened together and that won't be 100% clean no matter how hard you try. I'm thinking the liner will bridge across and form a pocket to hold water.
In the end, it's your rig. Let us know what you decide and how it turns out.

 

[Hay Dude]

He offered it and I was a bit surprised. I was thinking prime/paint.

 

[Snobdds]

Sand blast>primer>Top coat (JD industrial Black now called Blitz Black). You're not building a concourse quality truck, so don't overthink this and stick to the tried and true methods.

I don't think they make the JD industrial black as the same formula as they use to, but hopefully I'm wrong. That old formula was tough, because it had a lot of VOC's in it. Since you're not in Cali, you might be able to get it. If not use Blitz Black.

 

[Hay Dude]

A little more “fuel for the fire”.
We started a little sandblasting the frame and stopped. The rust jacking was bothering me so I took out a sledge hammer and proceeded to beat the the frame and the rust came out.

But now I got me a gap.

I think if I left it in, the fames would separate so much they would crack.

More time and labor.