Electrolytic rust removal setup

[Henrik]

I had a play with electrolytic rust removal in the weekend, and found it interesting. I had an old toolpost from a lathe, and also the associated washers and bolts that go with it to de-rust.

The method itself works fine, but my issue with the method I used was that i was fiddly to set up (basically, I ended up using a copper pipe hanging over a bucket, and then I suspended the bits from this using bits of wire, so that I could do all 5 bits at once (toolpost, washer, 3 bolts).

For smaller items, it would be much easier if the bits could just be "chucked in" into some metal basket (i'm thinking "chip fryer" style). Does anyone have any thoughts on why this would not be a good idea? I'm just looking for ways to get around the fiddlyness of setting bits up - for something like bolts, washers etc it's a considerable faff, so if they could all be chucked down into a tray of some sort, that'd be much easier. The tray would be attached to the battery charger.

Would a basket work as a faraday cage?

 

[rtbcomp]

The items would be connected electrically to the basket so current would flow through them, but current would also flow directly from the basket to the other electrode, in time the basket could get eroded away but I would guess the saving in time and faff would be worthwhile.

 

[atomant48]

For my zinc plating setup which is similar, I have seen people use plastic containers (old butter containers etc) with the copper wire threaded backwards and fowards so the parts sit on it. I find it easy enough to thread each part onto a piece of wire - gives something to hold onto as I move it through each stage.

 

[MattF]

The basket will only erode/corrode when it's out of the bath, so any loss will be due to the corrosion and subsequent removal when it hits the bath. Whilst ever it's in there and connected, it's safe.

It is a method which works surprisingly well. I originally had similar concerns about it working as a Faraday cage, (the basket outcome is yet further proof that the 'line of sight' anology is complete bunkum regarding this process), and the process obviously sinks more current due to the basket being there, but it does work surprisingly well. I made one a while ago to test, for the same reason. It was a pain in the backside stringing up nuts, bolts and other small pieces. That basket has had a fair bit of time in the vat and it hasn't dropped a beat. Just make sure that the stuff is grease free, and that any really rusty stuff you just make sure there's at least a bit of surface which has rust cleaned up as best as possible beforehand, so that the pieces can readily make contact with some surface, and you're good. I have a photo of the basket I use knocking about. I'll dig it out and post it shortly. It's no work of art, but it does the job.

 

[MattF]

This is the basket. As you can tell, made for functionality over form.

 

[Maker]

What about using citric acid and no electricity? I've tried both and found both to work well but I've never done a side by side test of the two. I use citric acid for everything now because you can simply throw things in like you said.

 

[MattF]

Citric is generally fine for some things, (tool steel is one thing which springs to mind), yet literally the kiss of death for others. If it's a piece where finish, effect, zero or minimal degradation of the surface etc. is important, citric is not the option to use. I have a pile of bits which look like crap due to citric, so it's not an unfounded judgement.

 

[Maker]

So will citric acid dissolve the not rusted steel then?

 

[MattF]

To be totally honest, I'm not sure exactly what it does. Some stuff just doesn't come out well, but exactly what's happening to it I'm not clued up enough on chemistry to explain. It's just what I note from eye and feel, and in direct comparison to using electrolysis on the same pieces or type of. The actual chemical intricacies are beyond my ken though.

The general type of behaviour I've noted is that steels will generally be fine. Brass can end up being pink, as if the surface metal is being leeched somewhat, and proper iron or variants of, barring steel, (even that can be hit and miss), just do not seem to like citric almost all of the time.

 

[wristpin]

Been derusting the inside of a fuel tank, works well using the fuel tank itself as the negative electrode , filling it with the electrolyte and inserting a positive electrode through the filler orifice but insulated from the tank.

 

[500e]

"The general type of behavior I've noted is that steels will generally be fine. Brass can end up being pink, as if the surface metal is being leeched somewhat".
It removes the copper content I think, happens to bronze props in salt water

 

[Henrik]

"The general type of behavior I've noted is that steels will generally be fine. Brass can end up being pink, as if the surface metal is being leeched somewhat".
It removes the copper content I think, happens to bronze props in salt water

Hmm, must be the zinc it removes, right? Given that zinc is much less "noble" (i think that's the term) than copper.

 

[Henrik]

This is the basket. As you can tell, made for functionality over form.

Matt, I like that a lot, very good idea! Is it a mild steel mesh or something else?

 

[Coo]

I bought kitchen chrome type shelf to make a basket to lay stuff on....but had to grind a lot of the chrome off as it was not as conductive....

Not happy with the battery charger being used, its an auto charger and keeps flicking on and off. Told my mate who is usng it just now to get a PC power supply to mod and use.

 

[MattF]

Is it a mild steel mesh or something else?

I'm not sure exactly what type of mesh it is. It's too hard to be mild, as I had a devil of a time cutting the stuff. The piece of mesh I cut that from is one of those things which was knocking about at my parents since I was knee high to a newt, and then it ended up here somehow. I was just glad to finally find a use for it other than gashing my leg or arm with the edge of it as I clambered by the stuff in the shed. What/where my dad originally got it from though, I have absolutely no idea.

 

[pedrobedro]

Would a basket out of a chip fryer work ? She'll never know you borrowed it

 

[MattF]

It would. Only problem with those is that the hole size is a bit large. A flour sieve would probably be the best thing for a fine mesh. It's finding a decent size one which is the problem though. A fine mesh is one of those things which you don't appreciate how hard it is to find until you're looking for some. I spent ages looking for something before I ended up making that basket.

 

[PhillipM]

Hmm, must be the zinc it removes, right? Given that zinc is much less "noble" (i think that's the term) than copper.

Yes, citric will strip zinc plate rapidly. Ends up as a scum on the top of your bath.