What Chemical is Best for Rust Removal (without flash-rusting).

[Guest simplyconnected]

Hydrochloric acid works great as a rust remover. It's available in Home Depot, Lowe's, and ACE Hardware as muriatic acid. After de-rusting, as soon as I rinse and dry my parts they flash-rust.

There's been discussion about home plating (or painting), but before we go there, all rust needs to be gone.

I have large-ish engine pieces that need to be de-rusted, like my valley cover, and down-breather tube, etc.

Last time I used HCL, I dried and immediately oiled the pieces. Next morning, the parts were all oily, but rust-colored. That's frustrating.

Does (hot tank) lye remove rust? I know it removes paint and greasy dirt (like for nasty shop fans).

[Bhigdog]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> After de-rusting, as soon as I rinse and dry my parts they flash-rust.

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That's pretty much the nature of the beast with that stuff. I cringe when I hear someone say to use that stuff to clean the inside of a gas tank. If you leave an open container of that stuff in your shop all your unplated tools will be brown, sometimes over nite. I don't have the rust removal answer for you other than bead blasting or a commercial dip tank place. Just thought I'd concur with your acid experiances....Bob

[msmazcol]

Evapo-rust. available at a good hardware store and also on line. It's a soak and be patient type though.

[Guest windjamer]

I took a washing mach. mtr. and mounted it with a 5 inch wire wheel and no shelds or obstructions. ALLMOST anything I can hold to that wheel I can clean to bare metal,including valve covers,oil pans and such.Yes I know OSHA would give me he**, but I get the job done.

[Ivan Saxton]

Try adding a proportion of Phosphoric acid to your hydrochloric acid, and use it on a test piece.

Ivan Saxton

[rsb]

I have had good luck using electrolysis to de-rust my parts. Of course you need to be able to submerge the part. It doesn't tend to flash-rust after like HCl and it doesn't attack the good metal either. All you need is a container, sacrificial anode(s) (rebar works for me), water and sodium carbonate as an electrolyte and a battery charger. Google has tons of info on the subject.

Best Regards,

Ron

[JohnD1956]

How about coating the cleaned parts with the NAPA Rust treatment ( a permetex product)? It will convert the surface rust on contact, and form a protective coating. Later you can lightly sand it before final priming and painting.

[Ben Bruce aka First Born]

Dave, The Evapo Rust mentioned above works great. I have used it on anything i could dunk in it. Any thing left more than an hour comes out clean. Dont believe you will be disapointed.

Ben

[Durant Mike]

Can you still get the product Ospho? I use to use it and it would turn the rust to an inert black coating that could be painted right over. Haven't seen it in awhile though.

[bill pritchett]

http://www.ospho.com/ is still sold there.

[Guest simplyconnected]

Guys, you all have real good methods, and I'm glad others have run into the same results I did with HCL. Bob Beck, HCL is nasty stuff... period.

I've been perusing the net on this subject, and I hit on a couple answers that you guys already mentioned.

For small 'dunk-able' parts, I would go with msmazcol and first born's suggestion, (Evapo-Rust) I wonder what's in it?

Certainly, wheeling rust off the metal is the preferred and fastest method, windjamr. THEN, I'd use chemicals to remove the residual rust.

I read, using phosphoric acid not only strips rust, it also coats the metal with a chrystal (which stops all further rust. It's really another 'dunk' method, or 'keep it wet' works too. I went to Lowe's. Employees scratched their heads when I asked for phosphoric acid (they had nothing). Then I went to Home Depot. Again, they're scratching, but one guy in Paint was willing to really look hard. We found a one-qt spray bottle of phosphoric acid for $8. “THE MUST FOR RUST” made by Krud Kutter. It’s the only phosphoric they had, and I’m thinking, “Crap! $32/gal is outrageous, and I need a couple gallons.”

Brought one qt home and tried it on those parts with flash-rust. It's slow (about 20 min.) but it really does the job!

Now all my parts are rust-free except for an oil pan I didn't get to. It has caked rust in spots, but it is real heavy steel. I put the phosphoric acid on, just like the other parts, and kept it wet for two hours. The heavy rust never budged. Ok, HCL! Nope, it sat on top for an hour. Then I got course sand paper, and scuffed it to the metal. Eureka, HCL worked again. Apparently, the phosphoric acid formed a 'salt' on top the rust that nothing but sandpaper could penetrate.

Ivan Saxton, you have a great suggestion. HCL is fast, but it promotes rust. Phosphoric acid removes thin rust, then puts a protective barrier on the metal. I never thought of mixing the two. I only did half the oil pan, I'm going to try mixing for the second half.

John De Fiore, your NAPA product's description sounds exactly like phosphoric acid. If it is, that stuff has the best properties for metal prep. Just a thought, why not just paint over the phosphorus? It's already etched into the metal, and paint will stick to it real well.

I'm used to using gallons of HCL. It's cheap at about $6.50/gal. HCL used BEFORE or WITH the phosphoric acid, makes parts ready for the chromer (or painter) in no time.

Ron, I don't know much about electrolysis other than for electroplating. In my case, since the parts will be plated, I could. Frame parts are another story. Rust converter paint (POR-15 stuff) is made for that.

To summarize, so far the best treatment is, wire brush as much as possible. If deep craters remain, HCL. Wash the part real well, and use phosphoric acid, (or Evapo-Rust); it will clean-up the flash, etch to the metal, and deposit a protective coat that is good for 12 months. By the way, after using the MUST FOR RUST, I still have over 3/4 qt left.

Thanks to all you guys. I was confident you would come through. This is a great site for us to share and learn. Any more ideas are always welcome.

Dave

[Guest]

Of course you could always resort to a bio-degradable method of rust removal that has been around for almost as long as there has been steet. Works great for thigs that you can dunk. A 50/50 mixture of molassas and water. You can use it over and over and when it is finally depleted or you don't need it any more just pour it out in the garden.

[KenHupp20]

You might also check out rust -beeter on the internet.

[PRNDS]

I used Rust Kutter after I messed up on my table saw using muriatic acid. Rust Kutter uses acids and other stuff but it doesn’t rust afterwards. I used a razor scraper and Rust Kutter and it made short work of returning the table surface to a new finish. 

[Tom Boehm]

EVAPO RUST   is the way to go!!!!    Non toxic. When it is depleted you can dump it down the drain. It has an ingredient that prevents flash rust. It will only attack rust. It will not eat away at the solid metal underneath. I used to use phosphoric acid but I prefer Evapo rust. I think it works about as fast as phosphoric acid and is not hazardous. It will not remove plating. 

[jan arnett (2)]

Depending on what I need derusted, I use electrolysis in a 55 gal plastic drum or a  commercial dip and strip company in Cincinnati.  Here are the fenders I got back for my 23 Moon as I picked them up and after  painting with epoxy.  Their process removes everything, paint, rust, lead and bondo.