Technical Tech: Simple rust removal with citric acid

I read on another thread about citric acid that you could use liquid dish soap to neutralize the citric acid. That is what I use after I clean the rust off with a nylon brush. Squirt some soap in a bucket, fill with water, rinse and wipe with an old wash cloth, rinse with water, dry and all is good. Some pieces I have used a metal wire brush on to remove the rust I had to put Gem Rust on, a phosphoric acid, to stop flash rust.

 

I could not recommend the use of any acid product on panels or items that have seams or joins in the construction.
It would seem that it is almost impossible to get all residue of the acid out.
It may look great and you feel satisfied that it is all gone, but just give it a few years and it will eventually start appearing in patches.
I've seen this occur especially after acid treatment of windshield frames that were cleaned by chrome platers.
I'm guessing they did not go to much trouble to neutralise their work, but it just never seems to completely wash out.

I would predict that once a panel has been acid damaged, it is highly likely that it is a throw away item after a prolonged acid attack has occurred.

 

I make up the baking soda solution, again 1 lb box to a spackle bucket size of water. I just swish the part in it for a few seconds or just leave it in for a minute or so if I have a basket of small parts.

I keep a Kitchen Aid plastic strainer with my acid dip containers. Old cat litter tubs with a lid are good to soak small parts in. I attach a wire to smaller parts and hang it over the container ledge so I don't have to put my hands in the solution.

 

im sure somebody already asked, I have a scwinn bike with lite to medium rust on wheels and other chrome parts ,handle bars etc., will this work on bike parts without destroying chrome?

 

I do this too. Works great.

No, it won't hurt chrome. Ok, maybe if you left it in for months, it might etch it a bit.

The active ingredients in molasses as far as rust removal is citric acid, so using pure citric acid makes more sense.

Yes, residual acid in seams and such is not good. But with thorough neutralizing and attention to detail, (pressure washer) there's no reason not to use this method.

 

Also, it will eat aluminum. I put an old Moon cap in my tank(just to see), and it started to dissolve instantly.

 

You just solved a a 48 year old mystery I've had. I left for a tropical vacation in Viet Nam in May of 1970 and return in May of 1971. I had just bought a 1929 ford 2 dr sedan that was in primer but had a newly chromed windshield frame. I left it in my parents garage with a light coating on wax on the face of the frame and when I got back, it was so rusted that it looked like it had been underwater the whole time. I could never figure out what happened.

 

Im sure what the chrome shop uses for an acid bath is far more potent than this. In fact this stuff is sold for making bath bombs, its that mild. I dont see any reason a soak in soda bathing wouldnt get in the seems just as the acid did, and in turn neutralize any residual. Don't over think it guys, the best way is order some and experiment for yourselves. Its rewarding and kind of fun to use once you realize the possibilities. Thanks for everyones input on the thread, I've learned some things myself. Thats what I like about the Hamb, the sharing of our collective knowledge makes this place a wealth of info.

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Wondering if could give me the name of the place where you purchased the Citric Acid online.
Thanks for sharing your knowledge with the rest of us car crazy guy's
Jimbo

 

I bought mine through Amazon. Quite a few vendors. Buy enough to get free shipping!

 

@Jimbo17 I just went on ebay and search "powdered citric acid" and looked for the best price. The sticker on the bag says www.soapandthings.com I think it was about 16$ free shipping for this 5lb bag. Or If you dont do ebay Algoma56 said its available on Amazon as well. I've only ordered online, not sure of any local retailers.

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A drilling fluid supplier will have it in 50 lb bags, if you have one local to you. Of course, if you know somone who works on a drilling rig...

 

I just ordered a 5 lb bag from EBay. $16 and free shipping. Going to give it a go as soon as it shows up this week. Sounds alot easier than media blasting every
little part to remove surface rust.

 

You'll love it, Bugguts. It leaves a very thin blackish residue that gets on stuff, but it comes off easily.

It's the only thing I would use on large flat sheet-metal panels that sandblasting can easily warp. Soda-blasting for removing only paint might be ok, but if you have rust and have to sandblast a '55/'56/'57 Chevy deck-lid, know that it can cause the middle portion of the leading edge to rise as much as 1/4" proud of the adjacent panel.

 

I’ve been going through several different tests on my Caddy. Phosphoric Acid, molasses, vinegar, citric acid. I need something I can de-rust the roof, because it has that wormy looking rust in the bare steel, and without dipping or blasting. By far the citric acid has worked best. Just mix it up, soak a towel and lay it down for a little while, use a slow turning wire brush to work the rust, and clean any little pits. Clean with baking soda after all rust is gone. Tough spots may need a second application. The finer the wire brush the better. Keep it wet while using the brush. I still keep it out of seams, like drip rails and similar.
I love EvapoRust, but the price, molasses worked well, but slow. Still a good choice for the guys not in a hurry, and I’ll bet it won’t affect paint from leaking out seams. Ospho has been my go to for 30 + years, but it’s more “work” to scrub rust pits with it, and getting it in seams is worrisome. I’ve personally never had a problem with it, but I clean the hell out of everything before paint.
The ease of just laying a citric soaked towel down and it working was the best part. Just keep it wet. Too easy, as it doesn’t lose strength before the rust is gone.

 

Tried it on these seat brackets instead of media blasting. Totally sold on it. Super easy, no physical labor except a rinse and scrub with water. I left them soak 3 days and checked them once just to see if it was working. Definitely going to do this more now.

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Citric acid is so easy and cheap! These were brand new but sat outside on a car for years. 18hrs later.

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You don't remember the name of the place Stan? Thanks

 

I had to trudge threw the snow in this beautiful storm we are having right now to get to the garage. It`s Terry. 402-676-7542. It`s by the water works plant, so I`ve been told.

 

Wow. I've been doing ectrolisis for years but this looks like a really good alternative especially for stuff you can't just drop in a tank. Thanks

 

I just mixed up a batch and through a cylinder head with surface rust on it into a tub and dumped the mix in. It started to fizz fairly quick! But here's the rub, once I dumped the mix in it started to smell like rotten eggs. I didn't think this stuff was supposed to smell. Should I be leaving this outside? And do you cover it while it soaks, or leave it exposed?

Edit: it didn't smell when mixed, only when it came in contact with the head.

 

I've always soaked my parts inside.

 

It eats aluminum, and will fizz as soon as it makes contact.

 

Good tips .

 

stanlow69, I noticed in your post what looks like some rubber taillight gaskets. Does citric acid rejuvenate them and bring them somewhat back to life?

 

Yes, somewhat. My batch is 3 years old now. Have a seat out of a 34 Ford in the tank now. Takes a little longer but still works.

 

That's what I needed to hear. Thank you, sir!

 

I have noticed a smell now and then, probably a reaction with grease and grime. I leave mine outside in a covered container, lid on loose to keep squirrels from falling in. If you have little kids around, put something over it. After the batch is done (used up) I mix my rinse pail of baking soda in it and dump it down the storm drain in front of my house.

 

No young kids here, but it is loosely covered. I left it in the garage overnight without any issues, plus it doesn't smell as bad today. I cleaned as much oil and crud off as I could before soaking it, so I don't think it's from the oils and such, but the runners had a bit of carbon still in them. I'm wondering if it was from that?