Electrolytic derusting advice

[mattthemuppet2]

Hi all,

I just set up a tub for electrolytic derusting, using some rebar, a constant current power supply and some sodium carbonate (washing soda). +ve to the rebar, -ve to the thing to be derusted



The question is - how good a result should I expect and how long will it take? The chuck in there wasn't hugely rusty and it went from that to mostly not rusty in a couple of hours (7V and 1.2A), but isn't completely clean of rust after being left running overnight. I've also stuck a cross slide cover and a toolholder in there (one on either side of the chuck) and left those overnight at 3 - 4V and 2A, but they don't look any different.

Did they volts drop because I have more items in the bath?

There are plenty of bubbles coming up from the items (lots at 1.2A and a storm of them at 2A) and slightly fewer coming from the rebar. Are bubbles supposed to come up from the rebar?

Should the items be completely free of rust or should I expect some wire wheel work to remove the last of it?

Any other suggestions?

 

[dracozny]

This method seems to work great for removing a majority of rust from badly rusted items. I might suggest using a larger anode such as a rotor instead of rebar. the solution also could be too light on electrolyte as well.

https://www.youtube.com/watch?v=y4yYF8gSHdA

Electrolysis works off of the more jagged areas first, and bubbles forming is normal. You should notice more bubbles on the part being derusted vs the anode.

voltage wise you are creating a parallel circuit so you will see less voltage per part.

here is the Tublacain version if you haven't seen it. http://youtu.be/ka6ArN_ehas

 

[shoeboxpaul]

Those bubbles are Hydrogen, the same stuff that the Hindenberg was filled with. Keep your tank in an area with no flames or sparks and if possible , ventilated. Watch this video: http://youtu.be/ka6ArN_ehas
Tubalcain does a very good presentation.

 

[Billh50]

I usually use a battery charger when I use this method. I think the more amps the better and faster it works.

 

[mattthemuppet2]

This method seems to work great for removing a majority of rust from badly rusted items. I might suggest using a larger anode such as a rotor instead of rebar. the solution also could be too light on electrolyte as well.

https://www.youtube.com/watch?v=y4yYF8gSHdA

Electrolysis works off of the more jagged areas first, and bubbles forming is normal. You should notice more bubbles on the part being derusted vs the anode.

voltage wise you are creating a parallel circuit so you will see less voltage per part.

here is the Tublacain version if you haven't seen it. http://youtu.be/ka6ArN_ehas

thanks Drac. With the rebar I was trying to get all round coverage to avoid the line of sight problems I've read about. I'll scout around the scrap yard and see what I can find. I threw a bit more sodium carbonate in this morning (not very scientific I know) so that may help. Thanks for the videos, I think I'm doing it mostly right (wouldn't stick my bare hands in washing soda though).

I'll see what the parts are light when I get home. It'd be nice to take the chuck apart and get that done.

Those bubbles are Hydrogen, the same stuff that the Hindenberg was filled with. Keep your tank in an area with no flames or sparks and if possible , ventilated. Watch this video: http://youtu.be/ka6ArN_ehas
Tubalcain does a very good presentation.

very true. I've put my indoor firework testing on hold for the duration Good point though, I'll be careful. It's in an attached garage that's used for storage so nothing much of risk in there and I don't use the room for anything else.

I usually use a battery charger when I use this method. I think the more amps the better and faster it works.

I'll keep my eye open for one at the garage sales this year. WHat I'd really like is a 30V 10A adjustable power supply, which would work very well for this and for anodising (current PS is 250V/2.5A which will just about do), but that'll have to wait for more funds.

 

[randyc]

...Did they volts drop because I have more items in the bath?...

I would imagine that the voltage drop was caused by the amount of ferrous oxides now in solution in your bath. I know nothing about this process but it would seem like the solution should be changed regularly, like PC board ferric chloride etchant. Just a suggestion -

 

[Billh50]

Electrolysis to remove rust will actually stop all by itself once the rust is removed from the steel. for a 5 gallon tank I use my battery charger set on the 30 amp fast charge setting and leave it run overnight. I have taken some heavy rust off parts this way. The one thing you should do though is to remove any loose rust first. My parts come out with a dull grey metal finish with no rust left. You do need to have enough washing soda in your mix. A bit too much will not hurt the process but does not help it either.

 

[churchjw]

You may get better results if you sandblast the rebar. Bare clean metal works better for the anode. I have used solution till it was to nasty to stand and it just keeps working but a build up of rust on the anode slows then stops the process. What I do is keep the solution in a bucket with a lid. When I am not using it the particulates settle to the bottom. I poor off the clean solution then dump the sludge around the flowers in the yard. It is basically iron. Every so often I let the anode plates dry out and then sandblast them. Also if you have some scrap steel that you are tossing out anyway. Put it in your set up using it as the anode and your normal "anode" as the part to be cleaned. Leave it running over night then toss out the scrap steel. This will help keep your anodes clean. Any oil on the part will also affect the process but it just strips paint off.

Jeff

 

[mikey]

Matt, the surface area of the anode, the cleanliness of the electrical contacts and the cleanliness of the parts being de-rusted all matter.

I use bare sheet steel, about 20 gauge, about 10-12" square for anodes; they are wire-brushed before every use. I have four of them, one on each side of my rectangular tank. I sand the anode and the part to be de-rusted where my electrical connections clip on so contact is assured. I wash off as much oil off the part as possible before it goes in the solution. Keep your parts off the floor of the container.

I also use a battery charger set at 10amps as a power supply. You do not need to add more soap as the solution evaporates; just add water. The solution will work as long as you can stand the gunk that builds up.

I've done everything from lawnmowers to anvils with ERR and they come out completely free of rust. I find that the surface area of the anode and good clean contacts are the most important things to ensure.

 

[Alan Douglas]

Rate of electrolysis depends on the current, but current being spent making bubbles on already-clean iron is "wasted" though it doesn't hurt anything. That could be minimized by placement of the electrodes to put the active area where you want it.

Whether you achieve sufficient current flow by more soda, cleaner anodes, closer separation of the electrodes, or higher voltage doesn't matter.

The total current will divide over the work-piece surface and may change with time.