Cathodic cleaning.

True, however I intended moving it about a bit. ;-)

There is something weird though and it may have been down to the fact that coat hangers are plated or something? The one I made into a loop and placed within the drum (on spacers) seems to have built up a whole load of 'stuff' (much more than the main anodes) but even when used on it's own doesn't seem to provoke the same sort of activity as the main anodes did?

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wish I'd done chemistry at school now. ;-(

Cheers, T i m

Reply to
T i m
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T i m

Reply to
T i m

Ah. I was just going by what it said here:

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" At the cathode (the object being de-rusted) the negative wire supplies electrons. Therefore, something must gain electrons at the cathode (reduction). Two things are reduced at the cathode, water and the rusty iron. The evolution of hydrogen from the water plays a beneficial role in the cleaning process. The tiny bubbles forming at the surface blast things off the surface that aren't stuck tightly. Loose rust, grease and even paint are removed by the action of the hydrogen bubbles. This process is sometimes called cathodic cleaning."

Ok.

Right.

As it mentions in the text (and I liked the sound of. Nothing like being half way to somewhere then remembering .... ).

And that's not good.

(I think I may have got round this by using a bit of coat hanger to bring the connection out of the solution).

Sounds like a good tip. I must admit to double checking I'd got them round the right way and sorta remembered it as (sort of unusually unless you are used to working on old cars ) the 'object' is -Ve.

Cheers and thanks for the warning. ;-)

Cheers, T i m

Reply to
T i m

It looks as if you may have found your true vocation. ;-)

Reply to
Gib Bogle

Well... you takes your chances if you want. Oil on brake shoes soaks in and comes out very very slowly, effectively ruining them. I cant see a light rust film being a problem.

I dont see any need for fancy shapes, just a bit of metal poked in the water is fine.

Yes, I assumed you'd remove the outside electrodes, since there's no reason to strip the rust & paint on the outside.

Scrap food cans are surely cheaper, and dont need cutting.

NT

Reply to
NT

I have no practical experience of cathodic cleaning, so cannot say. My knowledge of the shadow effect is from plating items, but the principle is the same.

Colin Bignell

Reply to
Nightjar

I would imagine that coat hangers are plated, though whether it's zinc I'm not sure. I thought zinc oxide was white though with iron oxide contaminants who knows.

Any current that flows ought to be a function of anode surface area and distance. A wire doesn't have a lot of area, how would this compare with your main anodes? Zinc oxide is a pretty good insulator as well.

Reply to
Fredxx

No, the fizzing will continue even if all the rust is gone. The solution won't exhaust, the soda is just there to let the water conduct better and doesn't get used up.

The larger the surface, the less resistance, the more current for a given voltage. S'why I like the ally foil...

The electrodes get eaten by the oxygen produced, so don't spend money on them. I'd pour the solution down the drain -- no worse than oven cleaner on an aluminum pan or sheet can be.

Beware that you've got a hydrogen-oxygen mix in the perfect ratio to go bang, and bits of metal connected to a power source that will spark, even underwater. And your power supplies might not take kindly to a short-circuit. You *will* short circuit the drums and electrodes, eventually. Might want to stick in some sort of fuse, even if it's just an inch or three of single copper strand in a choc block.

Thomas Prufer

Reply to
Thomas Prufer

IRTA "Catholic Cleaning".

Reply to
Huge

Baptism, innit?

Thomas Prufer

Reply to
Thomas Prufer

Seems to have worked before?

Well the worst case was I had a an old moped that soaked it's brake shoes in oil (engine in the rear wheel and a seal went). I boiled them in detergent and they worked fine thereafter. However, I wouldn't contaminate them on purpose and am careful to not do so when reassembling any brakes etc.

Agreed, but you know when you think these things are going to only be a couple of weeks then take 6 months ...

If you saw it in action it would suggest different. The 'reaction' is much more visible nearer the electrodes are to each other.

I hadn't initially as I didn't /mind/ if it also stripped the rust off the studs and the other areas. I started it all running again first thing this morning and I'm going to take one out and give it a rinse and clean and see just how complete the processes has been. If it still needs more on the inside of the drum I might restart with some fresh solution and 'internal' electrodes only.

Ah, good thought, if I can find something of a large enough diameter that we need to use up out of the cupboard. ;-)

Cheers, T i m

Reply to
T i m

Ok.

Understood, thanks.

Hmm, and easier to form into a ring .. ;-)

I was thinking a 12mm diameter length of Rebar could probably be used for a fair time though?

I was thinking that. This morning (left overnight) the material has settled out and left the 'water' pretty clear. I could remove the hubs then let it all settle again and just put the sludgy bit in some newspaper and in the bin?

;-)

Good idea. At the moment it's all pretty 'Heath Robinson' with wires twisted together etc (not really 'me' but it worked so ..).

Thanks very much for all your help and advice so far.

Cheers, T i m

Reply to
T i m

Yes, but you don't need thickness as much as area. Less shadowing and less resistance, so sheet metal would be better. Some sites recommend using stainless, as some types don't get attacked as much by the oxygen. So see if you can find something stainless free, like a washing machine drum, or an old sink.

Sounds good.

Thomas Prufer

Reply to
Thomas Prufer

Gotcha.

Hmmm ... ;-)

Cool.

I've just taken one drum out again and it is looking very good. I gave it a quick wipe round with a Brillo pad and it does seem to be back to the base metal, even on the frictionable part (so much so you can now feel a slight wear ridge on the inside) . ;-)

I did feel a couple of 'bit's' but still but nothing that wouldn't come off with a quick scrape.

Right, now to find something to that will take the rusty end of the suspension units. ;-)

Cheers, T i m

Reply to
T i m

Born-again brake drums?

Reply to
The Natural Philosopher

I keep reading this thread as "Catholic cleaning".

Reply to
Andrew Gabriel

Hell of an echo in here.

Reply to
Huge

In article , T i m writes

More pics when ready please, I'm enjoying this one :-).

Reply to
fred

Right, before and afters of the drum but the inside has only had the anodes on the outside (so most of the inside would have been in 'shadow' as such).

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did give the drums a good wash down and the insides a quick wipe over with a Brillo pad but I think you can see a marked improvement.

Towards the end, rather than having the drums insides facing upwards side-by-side in a flattish box with the anodes running down both the long sides (at an angle as they were longer than the box) we stood the drums on edge at either end with the insides facing the middle and the anodes also in the middle but only half the hub submerged. You could see the bit that had been submerged further de-rusted after only half an hour or so.

Yesterday I found another otherwise good PC PSU that had a burnt main connector [1] so I opened the case and trimmed all but the 12V and equivalent number of grounds and the start and earth wires back to the board. Then I stripped the ends, twisted them together (in groups ) and soldered a couple of meters of heavy duty (17A) red / black flex to that (and suitably heatshrinked). As this PSU has a mains on/off switch I'm probably also going to join the start / earth pair together inside as well so it becomes a straight 12V PSU. I'm also going to fit car blade type inline fuse holders as per Thomas's suggestion.

This means I can run two systems independently (as there are a fair few bits I need de-rusting). ;-)

Cheers, T i m

[1] This project has been a good reminder re why I rarely throw anything away . Even when faulty as for it's primary purpose it may well have a perfectly good secondary one without smelting it down and re-forming it into something else. ;-)
Reply to
T i m

Excellent result, the close-up pics show how much it has been improved.

For me it is the potential of cleaning the more intricate parts that would be of benefit, if I had looked inside the hub you showed in previous pics I probably would have scrapped the lot on the spot.

Reply to
fred

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