Rust Removal

[Darren]

I decided I wanted to try something different this evening.....so I thought I'd have a go at electrolytic rust removal.....

Having read up on a couple of sites it looked simple enough so I had a dig around to see what I had to do the job....

The kitchen cupboard revealed these two ingredients.....a good start



The subject was to be the base plate from my pillar drill which I've had for many years...rather neglected you might say...



I rigged up a half barrel for the container with some sacrificial steel bars for the anodes....(the negative poles)
Along with my car battery charger...which turned out to be useless for this application as it stated the battery had too low a charge so wouldn't switch on. It does this for low batteries as well which is really helpful.... Automation...who needs it.....




So I dug out a "proper" power supply from my collection....proper as it will give full control over voltage and current unlike a battery charger.
Apparently control over current is more important than voltage and we don't want too much of either.



The subject to be de-rusted is connected to the negative making it the cathode.

This is approx one hr later, the water was has gone from perfectly clear to mud in a very short space of time....



Some figures,

I decided to use caustic Soda as it's stronger and should help to loosen any paint. About 100g in this tub
(edit, that's a mistake....I used Soda Crystals not Caustic Soda)

Voltage is around 4.5V and current is 500ma

(the soda is to help the water become a better conductor)


Now to leave it overnight and have a look again tomorrow to see how it's getting on......

[Darren]

And this is what I was greeted with when I opened the garage door today.....looks promising.....



That crud it about 2" thick





Time to dig it out and see where we are



A quick brush over (no hard work here btw) and it's nice to see what's left of the paint almost fall off



It's hard to tell from the pic, but this is down to the bare cast iron with very little rust left. Mostly what was hiding under the paint that was still attached.



So it's gone back in the tub for another blast.....I could do with a full size barrel instead of one cut in half to do the whole lot in one go...

[Stilldrillin]

Very nicely done Darren!   

The gloop looks very similar to school dinner tomato soup....... 

David D

[Stefan Pynappels]

Well done, are you going to paint it again or protect it some other way?

[Darren]

Well done, are you going to paint it again or protect it some other way?

No, I'm going to leave it outside to see how quick I can get it to rust up again......


Yes, a re-paint in on the cards...prob be another thread 

[Darren]

The gloop looks very similar to school dinner tomato soup....... 

Send me your addy David....we wouldn't want it to go to waste now would we.......

[Stilldrillin]

The gloop looks very similar to school dinner tomato soup....... 

Send me your addy David....we wouldn't want it to go to waste now would we.......

BLEURRRR!!!!!!!!

[Bernd]

And a quick sand blast and it would look like new. 

Nice experiment there Darren.   

Bernd

[Darren]

I just realised something.....

I used Soda Crystals aka washing soda not Caustic Soda......

This is much less aggressive and safer to your skin etc, the mixture can even be thrown on the garden when you are done as some plants will benefit from the iron content.

A caustic soda mix would really need to be disposed of carefully.

Now that I have seen that the mild solution strips paint off I'll probably not try the caustic soda as I really see no need.

[Darren]

Bernd, no need for the blasting, it really is stripped back down to the base metal. The pic's are not showing this too well....

[CrewCab]

Nice one Darren  ................ though I'm with David D, the  garden can have the soup 

CC

[bogstandard]

For smaller parts and a little less exotic setup, you could try this.

http://www.arceurotrade.co.uk/Catalogue/New-Products/Shield-Technology-Products

Horses for courses.

Bogs

[Darren]

No thanks.....far too expensive...I've been down that route many times in the past.

There is nothing exotic about what I'm doing. It's just a bucket, some scrap metal, water and about 20 pence worth of washing soda that will last a very long time.

OK I'm using a fancy power supply, but an old phone charger would work equally as well.

Electrical cost, well 500ma at 5V is 2.5W, that's about 250hrs to use one unit of electricity at around 14 pence. So around 1.3p per 24hrs


That £12 tub wouldn't be enough to clean my one part, never mind the rest of it. You'd be better off with a 26p jar of vinegar, it'll do the same job.
Or a gallon of brick cleaner from your building merchant, mix with wallpaper paste and you're away.
And then there is the de-greasing and paint stripping to be done before hand....


Of course all this only works if you can submerge the part.

[Bluechip]

I'm with you Darren, used your method a lot, 12V 2A wall wart is series with a  55W headlamp bulb. (Won't light up much BTW)

Good for getting ally pinning out of files.

You can use it with non-submerged parts, use a flannel 'poultice', tape the anode to it. Keep it wet.

Works well, dump the bit in, leave it to it.

My sort of energetic activity 

Dave BC

 

[Jonny]

Nice one never thought of trying that. Thought those electrolytic cleaners were something special.
For general metal cleaning you can boil metals with washing soda.

I have a couple of psu's i used for my anodising, one dual output very similar to yours the other a Maplin 0-30V analogue jobby as backup.

You say this removes the rust to base level, therefore if say thin walled tube with pitt marks would it eventually remove in the holes without eroding what you want to keep?
 

[Darren]

Dave that reminds me, I used to use Caustic Soda mixed with water and wallpaper paste to strip paint of woodwork, doors and such.

Make the goey mixture up, cover the door etc and then cover with wet towels and such. Caustic works 100 times better if it's warm. So if you can put the doors outside on a sunny day the results will be amaizing. You have to keep it wet though by sprinkling with a hose now and again.

Glad to hear this de-rusting lark can be done in a similar fashion.

You might want to tell everyone why you use the headlamp bulb....just in case someone tries this without it.....


Jonny,
It should only remove the rust and not touch the base metal. Only try this with steel or iron or you may have a little irreversible disaster on your hands.
That's unless you want to destroy alloy like in Daves files.....good tip....

[Bluechip]

Johnny,  as far as I know, it is non-aggressive. I have certainly left stuff in for several days, all it does is gets the rust off.

It does get into pits, and cleans 'em out.

I usually scrub the bit off with detergent, dry it, then slap some 'Bondaprimer' on it.

Some steel I did several years ago is still rust free.


Dave BC

[Bluechip]

Darren,

I was first shown this  method about 40 yrs. ago by a guy who was a 'conservator', used to tart up stuff for museums.

The first occasions I did it was with a Davenset Charger, mit selenium rectifier thingy.

He told me to use a limiter, so I always have. I presume 'cos ham-fisted varmints like myself cannot be trusted to assemble the contraption without shorting the thing out. No benign current limiters in those days ... just popped fuses. Or poisonous rectifiers gaily blazing away. ...
Ah, happy days of long departed youth ...

I suppose I could stick one together, and meter it. Or just assume the geezer knew why even if I don't ..

Dave BC

[Darren]

Being a cheapskate I've tried ordinary garage floor paint on metalwork with some surprisingly good results. Even painted onto firm rust it seems to hold fast for many years.

It's what will be going on this pillar drill.......

[bogstandard]

Darren,

It is a bit far back in the post now, and I wasn't trying to detract from your post, far from it.

But for people that don't have the facilities you have, mine was an easy, although expensive second option, and they should also be given the chance to be considered, rather than just being thrown to one side, with very derogatory comments, as though everyone should go out and equip themselves to do it your way.

As I said, we don't all have the bits and bobs plus space to do it like you do. It might seem normal to you to have barrels and power supplies laying about, but to a lot of us, it isn't.

But sometimes, we need to get rid of rust as well.

Because of that, what I suggested is the way I would go, if I had rust to get rid of.

John

[Darren]

John, Sorry if I sounded dismissive, it wasn't meant to be offensive, but rather hopefully informative.

You were referring to a small part, that could be done on the bench in a jam jar, 1/4 teaspoon of soda and either a car battery charger or an old mobile phone charger
(but this should be done outside because of the explosive hydrogen gas produced, so room really doesn't come into it for most people)

Smaller parts should take less time so it might be done in an hour.

But rather than spend £12, a 26p jar of vinegar would achieve exactly the same result and come with it's own jar. I also gave some other options.

I have over the years had the need to de-rust many parts, and as such tried most methods inc an awful lot of propriety products. I have even imported them from the US at great cost.

Of them all just one product shone above all the rest, (in fact the rest gave pretty mediocre results in my opinion) a product called "Metal Ready" from the US but don't expect it to be cheap as it comes in gallons. They all share one thing in common, they contain acids of some description that does the work. The rest of the goo is just a carrier.

The truth is vinegar or builders cement mixer cleaner are not only cheap but is also just about as effective. cement cleaner esp so. Heck it the same acid as the propriety products use and normally at a 16% concentration so it's stronger.

I have never tried electrolysis to remove rust before, but I have to say it beats all of the other products hands down. There is no question about that in my mind now that I have tried it for myself.

If someone can't rig together a small vat with the necessary parts then they really are not trying very hard are they?

Washing up bowl, water, washing powder, cleaning agent or even salt, (even just plain water will work, it'll just take longer), a piece of scrap metal, small power source being a car charger, phone charger or even a battery even if it's out of your car.
It's so simple I cannot imagine anyone here does not have this stuff to hand or can't pop to the store tomorrow to fill the missing pieces of the jigsaw.

Most people can set this up without spending a penny, like I did....it's not hard.

But if you'd rather make someone else rich then that's your prerogative, I really can't afford to cos I'm poor ......

[dsquire]

Dave that reminds me, I used to use Caustic Soda mixed with water and wallpaper paste to strip paint of woodwork, doors and such.

Make the goey mixture up, cover the door etc and then cover with wet towels and such. Caustic works 100 times better if it's warm. So if you can put the doors outside on a sunny day the results will be amaizing. You have to keep it wet though by sprinkling with a hose now and again.

Darren

In order to keep from drying out you can wrap with clear plastic to keep the air from drying it out. Then you can lay it in the sun to keep warm until such time as it has striped the paint. This saves the wet rags and sprinkling which tends to dilute the solution and slows it down.

Cheers

Don

[shred]

I've used the electrolytic process as well as a number of the goops. 

We did a test with members of the metalworking group-- I took some 12L14 bar, noted for it's rusting ability, turned a very fine thread on it (to check on material removal and catch people jigging the test), degreased it and left it outside for a month.   Chopped it into sections and handed them out to be de-rusted by the members' favorite goops.

Of all them, Electrolytic came in a close second, the winner being Evap-o-rust-- a non-acid solution available around here for ~$20/gal, and re-useable many times over.  In addition to being slightly better on rust removal, it also sidesteps the hydrogen embrittlement that rumor has it can go with the electrolytic method if used on tools and the like.
 
Anyway, either far beats the rest of the competition.

[Darren]

Thanks Don, a plastic sheet.....oh so simple.......

Shred,

I looked up Evap-O-Rust and although they don't give much away it sounds suspiciously similar to Metal Ready, could be the same thing?

With Metal Ready I found it ate surface rust in a flash, was really quite amazing to watch. The largest parts I de-rusted were some 8x4 metal sheets I was using to fabricate floor plans for my Lotus 7 build.
I found while it was excellent with tackling surface rust, anything in a poorer state was still a problem needing abrasive action needed to be taken first.

The one thing that has really tickled me with this electo method is that it strips paint off at the same time. That can be a time consuming task on it's own...

[bogstandard]

Darren,

In my very young days, I used to hang around with a budding archeaologist, and he had read about your process somewhere for cleaning artifacts. It might have been a different chemical used.

So he set the experiment up on the table, and using some very dirty and encrusted roman coins (they abound around the area I live, very close to Watling Street), and he gave it a go. It worked fine, until he got too greedy, and decided to leave them in a bit longer than suggested, to clean out the heavily pitted stuff. Came back a few hours later, and all detail was missing off the coins, just blank discs.

Now I think this might relate to you comment about removing paint. I don't think it actually attacks the paint, but removes a very thin layer of metal, so the paint flakes away because what it was bonded to, isn't there for it to bond to any more.

Might be right, might be wrong, but maybe another slant on the process.

John