Awesome Rust Removal for intricate parts

[shenkmen]

And lastly, when in doubt, consult the experts. Here's where I learned about eletrolytic derusting more than a decade ago. These guys do it for a living and they're working with historical treasures that have been soaking in salt water for centuries:

Iron Conservation: Part I - Introduction and Equipment - Conservation Manual - Conservation Research Laboratory - Center for Maritime Archaeology and Conservation - Texas A&M University You're interested in the section on 'electrolytic reduction cleaning.' Note that they get their anode and cathode terms backward because they are archaeologists, not solutions chemists. Also note that they are probably much more worried about chloride (from seawater) than you need to be.

Here is the new link - http://nautarch.tamu.edu/CRL/conservationmanual/File10a.htm

 

[Robo McDuff]

De-rusting some of the hydraulic control valve assembly of a 5-ton

Trying to get the rust of the actuating lever of my M51A2. Reading up the alternatives including vinegar and molasses, steelypip came up with the idea of electrolysis and I thought to give it a try. Checking older threads through the links from Steelypip, I ended up with the clearest explanation you can have about using a mobile phone charger and clear pics how to do this. We have several old mobile phone chargers laying around, so why not. They ranged from 5 volt to 15 volt. However, there was only one with a clear black (-) and black-white (+) wire, so I used that one; it was 7.5 volt. The positive, I connected to a simple large nail. The negative I connected to the pieces I wanted to clean.

First five minutes I made a mistake having the + to the stuff to be de-rusted, but then corrected it and off it went.




The first two pics show the actuating lever and the pin being de-rusted in the first few minutes. Some bubbles but no discoloring of the water yet. The next two pics show the valve control assembly. I put only the down part where the lever turns into the electrolysis; I did not want to touch the interiors and the valve spool.

After two hours, the pin was back to really smooth, but the lever still had some rust, especially inside the hole for the pin which is the most crucial point. After that, I put the assembly in, but only 30 minutes (we had to go out). No new pics yet an I will continue tomorrow, but it looked a lot better already! This definitely works and I am going to use this more often; never knew it would be so simple to set up.

 

[steelypip]

Yes, that's the thing about it - it's easy and completely non-damaging to the work item as long as you hook the wires up the right way. The only thing I've had problems with was cooking my current sources with too much load.

 

[Robo McDuff]

Maybe a good idea to add some thoughts to this thread on how to preserve items directly after they come out of the electrolysis so to prevent they start rust immediately again. I can spout some ideas what I think but that would be without any basic knowledge on the topic. Not talking about when using electrolysis as alternative to sandblasting for your fender or sheet metal that gets to be primed and painted anyway, more like what to do with these rifle parts discussed or tools or stainless steel, that kind of stuff.

 

[steelypip]

I've thought about post-derusting preservation a good bit, as I've derusted quite a few things over the years. My answer is: it depends.

The good news is that electrolytic derusting does a good job of removing chlorine free radicals from the metal, which means that the metal will rust when it comes out of the bath, but the rusting won't be catalyzed and accelerated even if the item was exposed to salt at some point before derusting. You're starting off with a clean slate, chemically speaking, except for the aforementioned hydrogen embrittlement.

if it's an internal part of something that will be bathed in oil - I successfully resurrected a differential that had been left in a field partially open to the environment, then the answer is just to bathe it in oil. I got good results from this with the diff carrier and its components - just bathed them in used motor oil and stored in a heavy plastic bag until it was time for assembly. That's also what I did for the very first item I derusted - a fine Goes & Co. monkey wrench from about 1900. It was a rusty mess when I got it, but removing the wooden handle and derusting the rest resulted in a wrench that looked great -I could read the name and patent stamping easily in what I thought was pitted rusty metal.

If it's something like a bodywork item, then I tend to spray it with one of the rust catalyzing primers and then with a protective layer of an appropriate general purpose primer-sealer over that. If it's the backside/inside of something I usually use an epoxy primer. I did a battery tray on a truck about ten years ago and it remains completely rust-free after this treatment.

Stuff that gets too hot for normal paint, or I don't expect to paint for a while, or I might want to powder coat gets sprayed with phosphoric acid solution (metal prep). This puts an insoluble phosphate layer on the ferrous metal (iron phosphatizing - first cousin to Parkerizing) and makes it pretty resistant to corrosion while sitting on the shelf in the shop. A rinse in water after the acid has done its work followed by drying the part thoroughly renders it ready for application of VHT paint, powder coating, or shelf storage.