Sanding rust down...how much?

[2nd Day]

87 gw, bone stock. Here's where I'm at, not going for pretty, just solid.

Planning on using a rust convertor/inhibitor and bedlining on primer.

Do I need to go zero rust or is smooth ok?

I've done paint work, but not with this much rust before. Going to fill and reinforce the seams and holes once I clean them up.

Not looking to weld in new floor pans. Primary use will be on the trails.

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[tgreese]

Any pro will tell you to start with bright steel. Anything less won't last as long.

However, there are many possible shortcuts. I have an opinion, but it's not up to me to do your homework for you. This topic has been covered many many times before, and there is plenty to read and think about if you search. You can look at forums like autobody101, or any of the car forums.

One thing the autobody101 guys point out - the pros typically find an approach that works for them and don't experiment. A pro's recipe will work, but may not be the best or only way to approach the process. You need to read, think, and then place your bets and take your chances.

I would also point out that the makers of treatments and paints are in business to sell you the product, and whatever they tell you has to be assessed skeptically. Personally I like Aluthane, and that has worked the best for me of what I've tried. The Permatex rust treatment si also good, but all these treatments are bandaids to some more or less extent.

[2nd Day]

Any pro will tell you to start with bright steel. Anything less won't last as long.

However, there are many possible shortcuts. I have an opinion, but it's not up to me to do your homework for you. This topic has been covered many many times before, and there is plenty to read and think about if you search. You can look at forums like autobody101, or any of the car forums.

One thing the autobody101 guys point out - the pros typically find an approach that works for them and don't experiment. A pro's recipe will work, but may not be the best or only way to approach the process. You need to read, think, and then place your bets and take your chances.

I would also point out that the makers of treatments and paints are in business to sell you the product, and whatever they tell you has to be assessed skeptically. Personally I like Aluthane, and that has worked the best for me of what I've tried. The Permatex rust treatment si also good, but all these treatments are bandaids to some more or less extent.

Thanks Tim, I have and continue to research.

Wondering if a small sandblaster would be worth trying.

I'll read up on those products as well.

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[tgreese]

There's a guy on autobody101 that did all of his engine compartment of a full-size car with a spot blaster like this - https://www.tptools.com/Siphon-Fed-Spee ... ed+blaster Harbor Freight sells a similar one.

You can buy coal slag cheaply at Tractor Supply, 50# bag for something like $15. Sweep it up and reuse it, and you can afford to lose some of it.

[Stuka]

From my understanding, if you get the rust smooth, so there is no longer any loose bits, a rust converter will take care of the rest. The exception being in corners, you need to get as much out of them as you can, as there wont be enough surface area for the converter to work.

For most of those areas you show, I would use a wire wheel to remove that. Its in a big open area that is easier gotten too.

[letank]

the floorboards are always damp... so it is a tricky problem to get them pristine: either the door gaskets or the fresh air vents drip a bit of water on the front end... and it trickles to the back. The rust converter works... but not under constant humidity... In the winter month I started to pull the carpet on rainy days!

As for your back seat floor... time to pick up a welder and practice... I have been an epoxy guy for many years, but after over 20 years I picked up an inverter and messed up some panels... I really fubar a few times... but after a while you get the hang of it, fixed the motorcycle muffler, the frame on another off-road motorbike... front fender holes on the waggy. I need to visit my neighbour and use his plasma cutter.

[SJTD]

I had my freshly sanded roof out in the rain under an aluminized tarp on top of a blanket. Tarp leaked and I had bad rust. Might have been some electrolysis going on to help it along. Anyway I put a box on top and taped it down around the edges and blasted it blind through a hole in the box so as not to make too big a mess. This was with my home made pressure blaster.

I have a HF blaster with the hopper on top. Rigged up a gallon jug with a hose to feed it so it isn't picky about position of the gun. Still makes a mess but if you put a blanket over where you're working you can contain most of it. Do use a material like Tim suggested rather than sand to avoid silicosis.

Also have a spot blaster with a catch bag and various rubber doohickys that you hold against the metal. Works great and no mess but too small for your application.

[AMC-COMMANDO]

I have used POR15 over smooth or sanded rust areas and had good luck. Currently working on a 3B and used the POR. It will get scuffed and then a coat of bed liner inside the tub. Also going to be mainly a trail rig.

[2nd Day]

I'm on a tight FSJ budget so I'm trying converters and paint. Got the back sanded good. Well see!

Thanks all!

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[letank]

you can try milkstone from tractor supply https://www.tractorsupply.com/tsc/produ ... 1de21d1f65


or phosphoric acid... works really well... the underhood light was a rust capsule

UnderHoodLIghtFSJx.jpeg

[TeaBag]

phosphoric acid or "ospho" can be purchased at Home Depot for a reasonable price and works very well. Get as much of the loose rust off as possible. The more shinny metal you expose, the better- not only for the acid to penetrate, but also for whatever paint or coating you put over the top of it, to stick. SATURATE all of your areas with "OSPHO". For small parts, I will soak them, but for this I would put it in a spray bottle and spray it on. Follow the instructions on the bottle. Once the acid has dried (probably 24hrs), you can overcoat with whatever product you desire. Your best chance of preventing further rust will weigh heavily on how well your top coating (pain,. por15, bed liner ) can keep moisture away from the metal.

[2nd Day]

phosphoric acid or "ospho" can be purchased at Home Depot for a reasonable price and works very well. Get as much of the loose rust off as possible. The more shinny metal you expose, the better- not only for the acid to penetrate, but also for whatever paint or coating you put over the top of it, to stick. SATURATE all of your areas with "OSPHO". For small parts, I will soak them, but for this I would put it in a spray bottle and spray it on. Follow the instructions on the bottle. Once the acid has dried (probably 24hrs), you can overcoat with whatever product you desire. Your best chance of preventing further rust will weigh heavily on how well your top coating (pain,. por15, bed liner ) can keep moisture away from the metal.

Thanks, hadn't thought of those options.

I guess without spraying the undercarriage and living on the east coast with humidity it's going to be a constant battle.

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[2nd Day]

Trying out what I picked up on Amazon.

Looks like Pepto Bismol.

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[SJTD]

Looks like it did about as much good as Pepto Bismol.

[2nd Day]

Looks like it did about as much good as Pepto Bismol.

Well, yep.

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[tgreese]

Looks like this product is a rust convertor, like "Naval Jelly." It changes the oxidation state of rusted iron from "red" oxide (hematite) to "black" oxide (magnetite); it does not actually dissolve or remove the rust. The black oxide does not flake off like red rust, and the surface is kinda sorta stabilized - compared to how it was. Looks like your treatment worked mostly. Possibly it has a latex base that "seals" the surface once it dries. The Permatex rust treatment is similar, but seems to contain a lot of active ingredient, since it does not take a lot of material to turn a rusted surface completely black. These products need a top coat, since the converted surface is still exposed to the air and any moisture.

If this were mine, if I did not blast or replace the steel, I'd go at it with a coarse cup brush in an angle grinder and remove as much rust as I could. To me, that surface prep looks ... inadequate. The paint will surrender to the grinder well before the rust will be even mostly removed. Spend money on the brush and use any old angle grinder (Harbor Freight is fine). I would pick their cheapest one with a paddle switch.

I'd also suggest - the more rust you remove, the further and better your rust convertor will work. It's a chemical, and gets used up in the converting process.

Then I'd top coat with a good moisture-cured urethane - I like Aluthane. There are lots of options: Aluthane, POR-15, Rust Bullet, Hirsch Miracle Paint, Rust Encapsulator, likely many others. Aluthane is currently about $50/qt. These products cure by cross-linking water in the polymer, and will harden from the moisture in the air. The Aluthane site suggests filling the can with butane from your torch before you seal it, or else you'll have a urethane brick in a few days. I've had good luck leaving the top on, and punching a hole in the lid which I fill with a sheet metal screw. I shake the can and squirt out what I need into a paper cup. This will stay mostly liquid in the can until I use it all. The web site suggests you save up your projects and use the whole can in one session of painting.

https://www.mcmaster.com/brushes/brush-style~cup/

https://epoxyproducts.com/aluthane.html Try it - you'll like it.

[SJTD]

It may be chemically stable but it looks like a lot of it's ready to flake off. Be a bitch to remove but prolly flake off once it's painted. Just one of the perversities of life.

So I agree with Tim about the prep before using the magic stuff. I'd use a grinder. Carefully. Even heavy wire cup brushes seem to polish that stuff rather than remove it.

[tgreese]

A flap disk would be a little more aggressive than a cup brush, and less danger of removing a lot of steel than a grinder. Cup brush gets into the grooves and edges well, and does not wear out like abrasives. A rotating brush will shed wires, so wear PPE. Suggest you buy both and try them out. Both will fit on the arbor of a cheap angle grinder.