Electrolytic rust removal

[MattF]

Seeing as the topic of rust removal, (electrolysis &/or citric acid), rust removal crops up occasionally still, thought I'd pop this up here just for some basic reference regarding electrolysis.

I set up a vat a few days ago, & then around 3 this morning I was hunting around for a small piece of cast iron sash weight I had knocking about somewhere, when I decided to start it going. Peculiar hour to get the urge, I know.

Still need to tidy things up a tad on the vat front, & optimise the setup a bit, but it's usable as-is.

The vat. A raised bed bought from Aldi. For what it cost, a damn sight cheaper & quicker than making one myself. Some diagonals fitted to the legs for rigidity, & lined with some dpm or suchlike.



This is the first piece to go in there. The handle for the Drummond shaper.



Running it at 12V, currently drawing around 140mA. Current limited to 500mA max.



Piece for derusting connected negative, suspended underneath that wooden slat on copper wire.



The cast iron weight in the corner connected positive.

p.s: Can we please refrain from the Google/internet experts, or doom & gloom mongers, turning this thread into a one-upmanship or bunkum roll please. Thankyou.

 

[Onoff]

Torx screws too, show off!

 

[MetalMonkey]

I set up a vat a few days ago,

I hope you have notified the relevant authorities about all this!
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You are going to have to get vat registered now.

 

[frank horton]

tell us more....real world experience pls....

 

[MattF]

tell us more....real world experience pls....

I'm going to pull that out of the vat later, give it a scrub, & I'll take a photo of it. It won't be blemish free, but it should be less rusty.

I've cleaned the rust off, (flap wheel on angle grinder), & cut up a sash weight this aft to replace the manky, rusty piece I dug out last night, so when I fit both these pieces in the vat, it should improve performance slightly. Current will always be limited to ½A at the psu end though, so as to not overdo/rush the process.

These are the anodes to be.



8" long. I'm probably going to drill & tap the tops so that I can make a guaranteed secure electrical commection.

I use cast iron as it lasts much longer than steel.

 

[Gregb23]

What is your power supply? Is it a battery charger of some sort?

 

[MattF]

Nope. A variable bench psu. That way you can control voltage, limit max current etc. It's a process best done steadily, rather than simply letting it draw as much current as it can.

Taken the handle out of the vat & given it a quick scrub.



The remaining black is where the surface has pitted. That, I'll just leave as is. It's of no detriment to the piece. Removing that would purely be for cosmetics. Compared to the before, a notable difference.



That's just over 24 hours at 12V, & approx. 150mA.

 

[MattF]

What is your power supply? Is it a battery charger of some sort?

This is a psu I had purchased specifically for the task.



However, the cooling fan runs constantly on that. Annoying to listen to. So, this one got pushed into service for the task.

 

[JOEPRO]

Electrolysis (or however you spell it) is very effective.

I use it for MB parts with great success. Heavily rusted items just wash off the rust scale after a day or two. It's amazing. But stuff does quickly flash rust.

So I dry it then blast and epoxy prime to stop the rust.

 

[Turbo]

Great also for stuff with loose paint over rust. The process will remove any bad paint leaving a sound surface to paint over.

I use a pressure washer to clean the item off. Good for washing the anodes too. I find that if you don't clean them regularly the process doesn't work as well.

Doesn't work well on oily or greasy items so clean them first.

Ps - I hope you don't mind us offering some tips and tricks we discovered using this method of cleaning.

 

[MysterG]

I'd be worried about puncturing the DPM?
I use a plastic crate with a snap on lid to cover it when not in use.

 

[MattF]

In the first photo of it, there's a piece of wood atop it leant against the wall. That's one of two which will cover it when not in use.

 

[MattF]

Ps - I hope you don't mind us offering some tips and tricks we discovered using this method of cleaning.

Not at all. That's the intent & hope of this thread. The more opinions, techniques, experience etc. the better.

 

[Blobber]

So what's the benefit of this method over the citric acid?

 

[MattF]

In my experience of both methods, electrolysis is gentler on the piece, (if done subtly), & I've never had problems with it affecting the surface appearance.

Citric, even though it supposedly doesn't touch good metal, does occasionally, (in my experience. Others experience & opinions may differ), etch/alter surface appearance.

Hence why my personal preference is the former. I always achieve the result I expect.

Plus, there are other points such as you could leave the part in the vat for weeks on end, without issues. I'm sure I'm not the only one on here who has forgotten they'd left a part in citric acid, & found a crusty mess, several weeks later.

 

[MattF]

Fitted the new anodes today.



Solid core wire linking them, which means it also acts as a hook over the rear of the vat to prevent them trying to topple forwards.

 

[Turbo]

In my experience of both methods, electrolysis is gentler on the piece, (if done subtly), & I've never had problems with it affecting the surface appearance.

Citric, even though it supposedly doesn't touch good metal, does occasionally, (in my experience. Others experience & opinions may differ), etch/alter surface appearance.

Hence why my personal preference is the former. I always achieve the result I expect.

Plus, there are other points such as you could leave the part in the vat for weeks on end, without issues. I'm sure I'm not the only one on here who has forgotten they'd left a part in citric acid, & found a crusty mess, several weeks later.

Cast metal is very reactive with hot citric and will dissolve quickly.
Citric is good at getting into nooks and crannies whereas electrolysis works on line of sight so some areas can be missed.

I've found that electrolysis is very good on heavy rust and will slowly strip an object back to bare metal.

The thick solid copper wire from swa cable is great for suspending objects.

 

[Turbo]

Can I suggest the moderators pin this thread?

 

[Turbo]

The process can be used on reverse to age metal. Just use the object as the anode and it will be randomly eaten away.

 

[OJCar]

I add washing soda to the water.
This sort of thing, couple of quid in the supermarket.

About 1 tablespoon a gallon, helps improve the conductivity of the water.
Used Electrolyte can still be disposed of in a domestic drain.

I prefer to use an anode that curves around the piece being cleaned to help with the "line of sight".
Complex shapes sometimes need multiple goes with the anode and cathode in different arrangements.
Anode should be cleaned every couple of days.

I just use an old battery charger with some bulbs in series to limit current.