Rust Remover

Tom in St. Louis · Aug 12, 2023

I am sure this topic has been covered before so, sorry if it is a repeat.

I am looking for advice for a good rust remover for steel, something like a paste or jell. Don't want to sandblast. Since there is some pitting, it needs to get down into the pits and get the rust out.

I am also looking for advice on a good filler. I have Bondo, but wondering if there is something better.

Thanks.

Tom

rrlund · Aug 12, 2023

Why don't you want to sand blast? I took a tractor hood to a body shop to see if he could make it right. I had used a wire wheel on an angle grinder on it. He told me I'd have to have it sand blasted to be sure filler (Bondo) would stick.

Mike(NEOhio) · Aug 12, 2023

I've used EvapoRust with good results. If the part is too big to immerse you can cover the area with a ER soaked paper towel and the a plastic sheet to keep it wet. It works by chelation, not acid. A glass reinforced filler like Duraglass will hold up but harder to sand.

showcrop · Aug 15, 2023

Yes, this comes up very frequently, but usually on the paint forum. The far most popular answer is phosphoric acid rust remover/converter. You are correct in that you want to get down in the pits because you can't count on the blasting to clean them out. There are many different brands. The phosphoric acid not only eats away much of the rust, but also converts what is left to inert iron phosphate which is the same coating as they put on your impact wrench sockets. After giving it 15 minutes to work with some agitation you rinse it off aggressively to minimize any residue. I have the main two pieces from a Rest-o-Ride seat sitting in the rain right now, getting rinsed off.

Dave G9N · Aug 15, 2023

I would not use Bondo directly on bare metal without a primer and preferably a phosphate treatment like Ospho, Showcrop's milkstone cleaner, or POR 15 metal prep (Zn Phosphate). Any phosphoric acid cleaner can leave an iron phosphate coating that provides some rust protection. It is best to rinse with clean water. Any loose white powder will prevent the paint from reaching the metal.

Electrolysis is a good option for parts that you can fit in a plastic container. So I have read, but have not tried. As far as I can determine, the usual additive is washing soda or baking soda; something to make the water more conductive without chlorides. Epsom salts might work too. The lye mentioned in this quote is rough on paint, easy on iron.

(quoted from post at 22:09:27 10/16/21) For sheet metal and small parts, I take a 55 gal plastic drum and cut the side so a 16" wide rim will fit in there. Then I take some heavy scrap metal like mower blades and brake rotors and weld them to the fit inside the drum and some is sticking up out of one side. I fill it up with water and "PhUP", a pool chemical from walmart, and I also add some lye. I suspend my part to it does not touch the metal and connect a battery charger to it and the scrap metal. Sometimes only 60% fits so I flip it. There are youtube videos with the details. The rust comes off via electrolysis as Fe3+ and the paint where it was not rusted bubbles up from the lye. Power washing takes off that remaining paint and scotch brite gets any final spots. Small parts get passivation dunked in Ospho as you will get flash rust otherwise as soon as it dries. Larger parts and be sprayed with a trigger bottle. Spot putty will fill any major pitting. I prime and sand several times to build up while identifying rough spots. I use good PPG automotive PU which is better than those old tractors ever had when they left the factory, or even most cars. I follow the instructions for my paint and shoot it with a cheapo Harbor Freight top feed gun to get the solids I paid for, but I filter carefully and use dry air. No problem. I like to go a little wet, cheating by moving my parts into optimum position to avoid sags and that's how it dries, looking wet. Good paint is expensive and primer is cheap by comparison so really prime and sand several times, build it up.

EDIT Better link for electrolysis
https://forums.yesterdaystractors.com/viewtopic.php?t=1630663

This post was edited by Dave G9N on 08/15/2023 at 05:52 pm.

Rust Remover

Tom in St. Louis

Member

rrlund

Well-known Member

Mike(NEOhio)

Well-known Member

showcrop

Well-known Member

Dave G9N

Member

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