Electrolytic rust removal

[MattF]

I've read, but never confirmed myself, that high-carbon steels don't like electrolysis much - particularly springs, which can become brittle.

With springs, I've occasionally had the odd spring which seems to become somewhat stiff after being in the vat, but usually just left alone for a day or two, they'll be back to normal. I've never had one snap/break as yet.

I've never looked too indepth into the hydrogen embrittlement topic, but seeing how a lot tend to run their setups, I believe the main problem is simply that most rush the process.

If I can ever find it again, I downloaded a document years ago on electrolysis in conservation, & slow & steady was pretty much a primary point. Haste does not help the part being processed.

 

[Seadog]

I've read, but never confirmed myself, that high-carbon steels don't like electrolysis much - particularly springs, which can become brittle. Maybe someone can either confirm or dismiss this, but it might explain why the business end of your screwdriver bit has turned out like that.
I've had a lot of success at de-rusting stuff with an old Halfords battery charger. Often when parts are finished and cleaned I paint them immediately with Kingston Kurust - it prevents the flash rusting and provides a basis for subsequent painting if needed, and its water soluble so you don't have to dry things after washing. Otherwise, for things that don't need or want to be painted, its wd40 as someone else suggested above.

That wasn't electrolysis. Just immersion in citric acid.

 

[Turbo]

I can confirm that you need to use caution using electrolysis on spring steel.

I had a good set of external spring calipers that needed derusted.
After a day or 2 in the tank I took them out and the spring piece on top crumbled away when I tried to move them.

I've also had coil springs go crumbly.

 

[JohnH]

Derusting an E28 rear subframe

 

[Onoff]

Derusting an E28 rear subframe

I did similar for a Focus subframe but "in one" and using LOTS of citric acid:

https://flic.kr/p/2hJackm

 

[MattF]

One item I've found invaluable over the years, for dealing with small pieces, nuts, bolts, screws etc., is a metal basket.



That's currently sat in that bucket of water just to stop the pieces flash rusting before I scrub & dry them.

So much easier to dump small bits in a metal mesh basket rather than connecting them all manually. But one connection to make, that way.

 

[OJCar]

I have an old kitchen sieve I use the same way,
do sometimes get some odd results unless I put a secondary cathode inside the sieve, not touching it or any of the contents.

Be careful of using kitchen sieve tho, most of them are stainless steel gauze.

 

[MattF]

Leading up to photo's of a derusted item over the next few days, this has been sat in the vat for a few days now. Powered off whilst I'm at work, but I've found that as long as stuff's left in the vat & fully covered by the solution, power off, it won't start re-rusting.

Been running it at approximately ⅕ to ¼ of an amp.




It's the cast door from an old heated garden wall fireplace. A smallish fire would be built in there, then heat got drawn through & up through several chimney holes atop the wall.

I've taken it out of the vat a short while ago, to give it another scrub, & it's getting close to done.

It was obviously extremely well rusted before going in the vat, so it's lost some notable amount of metal & definition from its original condition over the years of being sat neglected in undergrowth, (the door's framework rotted away & this dropped out years ago), but I'm quite happy with how it's coming along. You can actually make out now what those lumpy areas are on the front of the door.

 

[Turbo]

Some pics of my electrolysis setup.

It is located in an open ended shed that gets the weather. I installed some 13a sockets inside a weather proof box that also holds an old battery charger.
The negative from the charger goes out to an electrical manifold.
This has 6 2.5mm2 leads with crocodile clips plus an old welder earth lead.
The positive charger lead is bolted to the waste metal.

My tank is a 200l plastic barrel with the top cut off.

The waste metal is made from 6 strips of 3mm steel sheet welded together into a hexagon shape to line the inside of the barrel. It is in 2 halves as a full hexagon would be too difficult to lift out for cleaning. The halves are linked with loops of wire.

These strips will need replaced soon and my plan is to chop up a 200l steel barrel to line the plastic barrel.

I suspend the stuff being cleaned in the barrel but this device is useful for items with a wooden shaft.

 

[MattF]

Leading up to photo's of a derusted item over the next few days, this has been sat in the vat for a few days now. Powered off whilst I'm at work, but I've found that as long as stuff's left in the vat & fully covered by the solution, power off, it won't start re-rusting.

Been running it at approximately ⅕ to ¼ of an amp.

View attachment 495531
View attachment 495532

It's the cast door from an old heated garden wall fireplace. A smallish fire would be built in there, then heat got drawn through & up through several chimney holes atop the wall.

I've taken it out of the vat a short while ago, to give it another scrub, & it's getting close to done.

It was obviously extremely well rusted before going in the vat, so it's lost some notable amount of metal & definition from its original condition over the years of being sat neglected in undergrowth, (the door's framework rotted away & this dropped out years ago), but I'm quite happy with how it's coming along. You can actually make out now what those lumpy areas are on the front of the door.

I'm classing this as done now. There's only a tiny amount of flaked rust left.

The rear of the door.



The front.

 

[MattF]

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View attachment 495602


View attachment 495603

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View attachment 495606

Some pics of my electrolysis setup.

It is located in an open ended shed that gets the weather. I installed some 13a sockets inside a weather proof box that also holds an old battery charger.
The negative from the charger goes out to an electrical manifold.
This has 6 2.5mm2 leads with crocodile clips plus an old welder earth lead.
The positive charger lead is bolted to the waste metal.

View attachment 495607

My tank is a 200l plastic barrel with the top cut off.

The waste metal is made from 6 strips of 3mm steel sheet welded together into a hexagon shape to line the inside of the barrel. It is in 2 halves as a full hexagon would be too difficult to lift out for cleaning. The halves are linked with loops of wire.

These strips will need replaced soon and my plan is to chop up a 200l steel barrel to line the plastic barrel.

View attachment 495609

I suspend the stuff being cleaned in the barrel but this device is useful for items with a wooden shaft.

Nice setup. You'll be able to get some good size pieces in there.

 

[Smallfry]

I use an old plastic loft water tank.

With two stainless steel drainers cut from sink units as anodes

 

[OJCar]

do sometimes get some odd results unless I put a secondary cathode inside the sieve

That should read "secondary anode" NOT cathode.
Sorry

 

[Turbo]

I use an old plastic loft water tank.

With two stainless steel drainers cut from sink units as anodes

You SHOULD NOT use stainless steel as your anode.
You create a nasty substance in the liquid that is very harmful.

Google hexavalent chromium!

 

[Seadog]

Yes, extremely nasty.

 

[MattF]

This is a chipping hammer I got from @RWD3M, last year. Popped it in the vat yesterday. Just given it a scrub down a short while ago.



Afters.

 

[Ace Paul]

Yes I did this during the #PLANdemic

A) you *MUST* turn the power off before poking around in the drum. If you get a spark the oxygen and hydrogen go bang

B) most odd never got a shock off the charger as it was did off the solution

C) solution works best 2 days old, when solution goes black ditch it, not on concrete

D) if turned off for sometime with brown water it draws tons of power

E) mine got left for few days, came to it, freezing cold but tank was 30degress c and drawing 30 amps.

F) DO NOT USE STAINLESS STEEL. Not sure why but it’s makes the water poison

G) not sure what difference metal stops the brown stuff

H) supermarket basket kind of affair to stop your item dropping and getting dissolved

J) not tried it yet. Positive rod to sacrificed anode, plastic drain pipe, then melt the end, stops it dissolving, hopefully

K) copper pipe as anode to coat your thing in fine layer. Need to repeat this experiment, as not sure results. Copper soon dissolve

L). Never got round to it. Two containers that look like wheely bins, top to top, bolted and tiger seal, then cut to make a coffin .

M) DO NOT SMOKE NEAR IT