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Awesome Rust Removal for intricate parts

Hooty481

Member
707
4
18
Location
Russell County Kentucky
I have a turbo exhaust manifold that has been setting outside for a while and I know there is some big rust flakes inside. do you think this would work for this process? will it remover or loosen the bigger chunks
 
I only stripped the insulation enough to make several wraps (about 4") around the chain. it bubbles right away like alka selzer. you will know it's working in about a minute. no bubbles no work. It may work better with the electrolytes that others have recomended but BS worked for me. maybe even just simple salt would do it.
I put the BBQ grill in last night and it came out covered in black grit. I put it under the hose it all came off. The grill looks great- no rust no crud...
 

68t

Active member
375
55
28
Location
Michie, ,tn
I left the battery charger on about 3 hrs. did not get a bubble. I will try again. I knew i did not get something right.
 

Hooty481

Member
707
4
18
Location
Russell County Kentucky
I have already burnt up one charger. Not sure why because nothing shorted out. I felt of it and it was really hot I thought no big deal then I came back about 2 hours and didn't see bubbles and charger was cold checked voltage and had none so I grabbed another one and here we go again
 
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Hooty481

Member
707
4
18
Location
Russell County Kentucky
The charger I burnt up was 16volts and 1 amp output. I tried another one and it was 15volts 900 mah output and I left it about 30 minutes and I checked out and it was really hot too. I found an old phone charger. Tried it. Not know the voltage I was curious and it was putting out 4.5 volts not sure the amps. But I didnt seem like enough. So I went with a lawnmower batter and a battery charger on 2 amps gonna see how this works. Been going for about 30 minutes.
 
i tried my battery charger and it just got confused and didn't work. i thought about hooking the charger to a battery as a buffer and then to the leads on the pieces. i just ended up using my cell phone charger. it got hot not really hot. like i said before look for bubbles right away. I think it is only a 9volt charger.
 

steelypip

Active member
769
68
28
Location
Charlottesville, VA
I have a turbo exhaust manifold that has been setting outside for a while and I know there is some big rust flakes inside. do you think this would work for this process? will it remover or loosen the bigger chunks
Yes, this works great on exhaust manifolds. An exhaust manifold was my second test part when I was in the 'this is too good to be true' phase of experimentation. Remember, though that the sacrificial cathode has to be in line of sight from the parts you want the rust to disappear from. For big pieces, this usually means you turn it over/turn it around in the bucket a few times to get all the sides and corners.

Your manifold will be gray and rasp-like when it is done. That's bare cast iron. You'll need to hit it with some rust preventative pronto or it will turn brown. I use phosphoric acid to pickle it, like OsPho, Prep Sol, etc. For exhaust manifolds, you hit it with the phosphoric, let it dry off, then spray it with header paint. I blow a heat gun through one port with all but one other blocked off to get the manifold hot and cure the paint. If you keep fingerprints off of it, the header paint will stick very well to the derusted, phosphate-coated iron.

I've generally used scrap black pipe from plumbing jobs as the sacrificial electrodes. I also had an exhaust manifold with broken ears that worked well. For something irregular shaped, I'm guessing the expanded metal mesh would probably be the ticket. Nearly anything ferrous metal will work, as long as part of it projects out of the bath to be used as a wire attachment point.

I've generally found the hardest part is maintaining good contact between the sacrificial electrode (I usually have several in a daisy chain) and the wires coming from the power source. The electrodes rust away, and so you're usually going after the out-of-water end with a bastard file, wire brush, or something to find some clean metal to get a connection to. It's not trivial, because running voltages are usually in the 2-5 volt range and it doesn't take much resistance to stop that entirely.

Power supplies do indeed have to be rated for the amount of current you're pulling. The good news is that you can adjust that current by using a lower concentration of washing soda or lye.

The easiest way, frankly, is to use an ammeter. Stay at about 50% or less of rated current on the supply and all should be well. If you overshoot, don't panic - just dip out some electrolyte and replace with plain water.

Also be warned that, like most chemistry, it's heat sensitive. Current flow goes up when the water gets hot. If you are putting lots of current into the water, you get it hotter, which increases current flow and next thing you know you've fried the power supply. Yes, I've done this. That's why I say do it at 50% of rated current.

As for current demand, that basically figures out as how fast you get your part cleaned. Current over unit area is a constant, so more is necessary for a bigger part to get the same rate of removal . If the voltage across the electrodes is high enough, you WILL get removal. It might, however, be very slow... If the inter-electrode voltage drops below the minimum EMF required to convert the rust into black magnetite then absolutely nothing will happen, except that your part will rust in the water bath...
 

68t

Active member
375
55
28
Location
Michie, ,tn
I got the bubbles going today , it works. I got a chunk of cast iron, file off some of the rust to get a ground for the pos +. side . then got the part that needed the rust off, file it so the neg. would ground. I hooked my car battery charger, red to cast iron. black to part. Put it down in the water with baken soda. It started to fizz.:jumpin: Put the two pieces about 3 inchs a part.:grin:
 

steelypip

Active member
769
68
28
Location
Charlottesville, VA
Can you use a mix of water and vinigar with this?
Yes and no.

Vinegar is great stuff. It's my favorite carburetor parts cleaner. That said, the chemistry of using an acid (acetic acid in this case) is completely different from using a base (alkali) as your rust remover. All acids etch metal. A salt, by definition, is the result of the action of acid on metal. So if you want to eat the metal to get the rust off the outside, acid etching (a-la Naval Jelly, Os-Pho, or whatever) works well. But it does eat the metal.

The alkali electrolytic process we're talking about removes no metal. It converts the layer of rust closest to the metal into black magnetite, which is easily removed with a stiff brush.


So when I hook the wire to the part being derusted that wire need to be out of the water? Is that correct?
Wires are copper. Copper in an electrolyte bath can result in copper plating. It's always best to have the sacrificial electrode sticking partially out of the bath so that it's easier to keep a good connection between it and the wire.

Steel alligator, crocodile, or battery clips are good for the work. These can be immersed in the electrolyte, but you'll need to scuff a spot down to metal to get good contact initially. Then the rust removal process will kick in and contact will only get better as the part gets cleaner.
 

Hooty481

Member
707
4
18
Location
Russell County Kentucky
i am getting some really good results with this. the only thing is if your part doesnt need to be completely submerged then how do you keep the other end from rusting when you turn it over to do the other side?
 

frodobaggins

Active member
2,861
16
38
Location
Ruston, La
i am getting some really good results with this. the only thing is if your part doesnt need to be completely submerged then how do you keep the other end from rusting when you turn it over to do the other side?
Cooking spray. (or other light oil) Careful not to get on the part of it you have left to do.
 

steelypip

Active member
769
68
28
Location
Charlottesville, VA
i am getting some really good results with this. the only thing is if your part doesnt need to be completely submerged then how do you keep the other end from rusting when you turn it over to do the other side?
Obviously immersing the whole part is best if you can pull it off. If you can't then derust part, treat it with something (phosphate is good), then flip it over and do the other part.

what will happen if the oil is on it when i am derusting
Nothing. That's the problem. The oil keeps the electrolyte from getting to the rust.
 
I just put my grandfathers cemetary medal in the vat. It is what looks like cast iron. They must have not had bronze available during the war. He was a WW1 vet Died Durring WW2. It had been at a small cemetary for years and years . It is in pretty rough shape. I plan to restore it and protect it. Lets hope this works.
 
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