Electrolysis using lye

Up until now, when performing electrolysis rust removal, I have only used the sodium carbonate solution, but I am considering trying the sodium hydroxide (lye) solution that has been touted by several individuals.

My reason for avoiding lye has been the safety issue and that sodium carbonate solution is pretty tame to have around.

But......all electrolysis users are familiar with the non-soluable carbon compound that is deposited on the de-rusted parts, right ? It is a pain in the kiester. Reading up on the archaeological preservation site, they talk about this deposit and say that if lye is used in the solution, the deposit does NOT form. There is no mention of any nuisance deposits using lye.

Perhaps some have further experience and can share their experiences with the lye solution. Is it correct that the non-soluable carbon doesn't precipitate when using lye?

I'd be very interested to learn where it is being touted that the black slime is Carbon. Removal of the black slime is relatively easy, as long as you remove it while wet. Use of lye in this process doesn't seem to offer any advantage I've seen in anything I've read. I certainly can't think of any advantage of lye that would lead me to dealing with the residue, or the corrosive propertys of lye.

I believe I said non- soluable carbon compound, not carbon. I just "cleaned" 14 spoked wheels and about a dozen other iron objects using electrolysis with a sodium carbonate solution. I found the deposition difficult to remove thoroughly and time consuming.

Here is a page discussing this very subject, in detail. The entire site is worthy of a peek ! I think I learned about this site here on Harry's.

http://nautarch.tamu.edu/class/anth605/File10special.htm#Sodium Carbonat

A quick read of that site tells me it is primarily concerned with rusted relics recovered from salt water, and that a lot of the information is either identicle to or follow on of the Texas A&M work. Items recovered from salt water are a totally different ballgame from fresh water or atmouspheric rust, primarily because the salt in the object and rust quickly contaminates the solution. Having done the process a time or 200, I've experimented a bit, and have yet to run into a problem with the so called "Carbon or carbon like" coating, because I remove the slime coating as soon as the object is removed from the tank, either by scrubbing and rinsing with dish soap (wife still can't figure out why consumption is up), or pressure washing. I've seen a lot of postings complaining about the resultant coating post process, and have yet to duplicate the problem, other than when I pulled a chunk of derusted iron from the tank and let it dry without washing it off. Metalurgists I've talked to tell me the coating might be FeO3, a form of iron oxide, but without analisys they can't be sure. I fail to see how carbon could be occurring in the solution, or getting precipitated out of the object being derusted. Problems might be occurring because the solution is contaminated, or overly concentrated, because greasy objects are being put in the tank, or because people are trying to run the process too fast, but I'm not seeing this problem. Since this is essentially an electroplating process where the rust is being plated onto the anode, a certain amount of attention should be paid to the solution, with particular attention paid to your water quality. Going to a lye solution will only increase your problems, and make the process a lot more dangerous.

Each part I "clean" is scrubbed with scotch-brite or something immediately after removal from the solution. For example, each 16", 5 spoke wheel takes me about 45 minutes to get it as clean as I want it and still it will smudge a bit.

The most likely source of the carbon compound is the carbonate ions. The web-site is clear about this substance. As it is non-soluable, it doesn't seem to interfere with a paint coating if the majority is removed.

Anyway, I think I still have one of my old college chemistry books which I will need to remember how to make up the sodium hydroxide solution by percentage. This isn't anything close to 'full strength' lye and I want to try it.

Just looking for some new ideas. Thanks for your interest.

[Robt.]

I set up an experimental tank in a steel drum to try the lye process. It's been a while and I didn't keep notes, but scaled up the proportions I had read elsewhere for the larger volume. The cylinder was from a salt water cooled marine engine. The cylinder had been baked at 800 odd degrees in a self-cleaning oven (junker of course) to burn off any oils etc. (Only to be done on very windy days!). Power supply was a marine trickle charger. There was lots of activity for a few hours and then the process more or less stopped. As the cylinder didn't seem to be completely done by any means, I assume something leached into the solution and interfered with the process. It's still sitting in the drum as it needs to be kept wet anyway once the salt has got in the iron.

Just an aside, but there seems to be some kind of chemical reaction with some vegetation that inhibits or even prevents/removes rust. I remember turning over one old engine that had sat on a rubbish pile for 30 odd years and the underside was literally bare metal like it had been sand-blasted a few days before. The rest of the engine was a ball of rust. Found a cylinder head lying in grass just off the seashore that was obviously off a salt water cooled engine and had been there for at least 40 years, looked very sound.

[Tom Kilgore]

What is the mix of sodium carbonate per gal of water? I need
to know so I can try this on some items. anyone????? regards tom

[Elden DuRand]

Tom:

What I do is to get the tank ready with the anode and the workpiece in place, fill it with warm water then turn on the juice and slowly add the sodium carbonate while stirring briskly and watch the amps. When the current quits rising rapidly, you've got enough.

Take care - Elden
http://www.oldengine.org/members/durand/

[Robt.]

A few photos I found of my first attempt. Was working well at that point!

http://img.villagephotos.com/p/2007-...9/DSCF0125.jpg

http://img.villagephotos.com/p/2007-...9/DSCF0126.jpg