electrolysis for rust removal- carbon plates

I started building Rob Roy many years ago and I still have the frames but they are horribly rusted. Of course I could cut a new set from clean steel or even buy some laser cut frames but I was wondering whether it is realistic to retrieve them from the scrap pile. They have the horns (hot brass pressings) riveted in place at the moment but they could be removed before putting them in a bath. It it worth it - thoughts?

Hi Phil

I don't see that you've anything to loose by giving it a go. Presumably you'd transfer the the horns to the new frames so drilling the rivets out would be part of that job anyway, so all you'd be risking is a bit of time, effort and fairly minimal cost rigging up the de-rusting bath. Got to be less effort than cutting new frames and less cost than laser cut ones. Definitely worth having a go in my opinion.

(edit added)

With the horns off, even less effort to give the rusty frames a soak in brick acid, over night would probably get all the rust off, it's worked wonders on a number of rusty spanners that I'd got lying around, shifts the black mill scale from hot rolled bar and plate as well.

Keith

Edited By Keith Long on 05/04/2014 14:55:41

Thanks Keith. I cut the frames about 37 years ago so it would be a shame to scrap for the sake of some brick cleaner (I need to buy some anyway - strangely - to clean some bricks).

I guess I'm after the strong brick cleaner rather than patio wash?

Phil H

For "Brick Cleaner" translate to Hydrochloric acid and I buy from these guys: APC Pure

Much cheaper to buy the strong stuff and dilute it, remember - Acid to Water - not the other way around.

graham.

Phil

The stuff I used was B&Q own brand "brick & patio cleaner". I think it's about 30-35% hydrochloric acid.

Stronger acid diluted would work just as well, probably the deciding factor is what you can get hold off conveniently. Avoid anything that says it's "green" and "environmentally friendly" - it doesn't do the job.

For anyone in Spanish territories "agua fuerte" is the same stuff.

Keith

It is not clear how rusty the loco is.
Very rusty from a proud builders perspective is just slightly tarnished relative to much of what turns up at car boot tool collections.
I suggest a phospohoric acid based treatment as it is less brutal and converts rather than just displacing the rust. You can paint it on and monitor the effect. I would expect a 5 in chassis to only need about 30cc if painted on. Enough to dunk it would be mostly wasted.

If you look at the specs of a lot of the brick cleaners you can see the cheaper ones are more diluted. Caveat emptor.

Bazyle,

I suspect the phosphoric acid treatment is similar to the rust removal products for cars - am I correct? I once used then to remove rust from a Vauxhall Viva (remember them?). It was effective and I also used it to clean up a rusted Myford lathe cabinet - also worked quite well. However, I suspect that these frames are going to take a bit more of a beating to clean them up followed by careful polishing with files and emery etc. Still - a hell of a lot quicker than making the frames again.

Thanks Keith and Graham. I think I will go to the builders merchants down the road and see what they have got. I will post a few pictures to show - hopefully - the success.

Phil H

There's been a couple of threads about the removal of rust, this one has quite a few ideas

**LINK**

Try Molasses. it takes a few weeks to work, but it does seem to work. When you are finished it's a lot less of a disposal problem.

"Self Check Out" at the supermarket might be welcome when you are absquatulating with their entire stock of Black Treacle (£1.15 for 454g from Tesco, but even the biggest in the UK only had 20 tins on the shelf).

Dilute 10:1 with water, (hot water is easier to dissolve treacle in than cold water). Put in a tank, drop in the parts, do other stuff for a while.

Cover the tank with a loose lid, or it will go mouldy.

There seems to be some chance of making a lambic Irn-Bru Rum this way.

That's a useful link Graham. Especially as they will ship to France

It isn't strictly necessary to follow the "always add acid to water" rule with hydrochloric acid as the reaction is no way near as exothermic as that with sulphuric acid however it is a good habit to get into you don't want to do it the wrong way with sulphuric! Hydrochloric acid is strictly a solution of hydrogen sulphide in water. A 38% solution is saturated and cannot be exceded, it is usually sold at about 30% and should be diluted to 18% for rust removal.

Russell.

Andy,

You had me rushing for the dictionary to find the definition of absquatulating

What on earth are the origins of such tongue twisting words? Sounds more like a form of medication.

Phil,

Molasses comes in 5lt containers, and will last a lifetime, for me at least.

8-10:1 mixture (water:molasses) stirred daily as it settles.

Geoff - Getting thoroughly peed off with back pain now!

Edited By OuBallie on 06/04/2014 16:15:30

Rusell says: Hydrochloric acid is strictly a solution of hydrogen sulphide in water.

A slip of the finger, I'm sure - it is really a solution of hydrogen chloride in water.
I the olden days of yore, it was also called 'spirits of hartshorn' - but I don't expect that Boots the Chemists would know that.

And Hydrochloric Acid is not the electrolytic way to go - that relies on Sodium Carbonate - washing soda - which is much easier to dispose of safely, and does not make holes in concrete.

Cheers, Tim

I think there is some mis-information here. Spirits of Hartshorn was an old name for ammonia solution. Hydrochloric acid was called Spirits of Salt. Hydrochloric acid was also known as Muriatic acid (and still is in some countries eg. Portugal).

Mike

Whoops - engage brain before posting. It was a slip of the brain rather than the finger Tim. Can I use age as an excuse?

Yes of course it's hydrogen chloride, a gas at room temperature and the solution does tend to release the gas so keep it away from your tools.

Hydrochloric acid will remove rust and scale just by soaking. Using a solution of washing soda with an electrical discharge is much safer if you are not used to handling chemicals.

Russell.

Russell, I take no credit for the link, some other kind soul on this forum pointed it out to me. As they are quite close by, a five minute drive, AND reasonably priced I have availed myself of their service and products on a number of occasions. I am off for some Copper Sulphate shortly.

graham.

Guys,

Maybe not quite the right section but this is related to rust removal.

I am very very pleased with the results from a quick (24 hour) dip of my 40 year old Rob Roy frames in brick cleaner.

The pictures don't really do it justice but they came out of the bath completely free from the rust shown in the first picture and not much pitting. The 'staining' around the main horns in the third picture simply wiped off.

A quick clean with rough emery cloth and they were virtually perfect.

I just need a dimensional check (I was 15 when I made them), a few more holes, Ill true up the horn slots in the miller and some new horns (I lost 2 out of 6 during the removal process).

Thanks chaps. That saved me just one or two hours hacking out new frames and its nice to be making use of the originals.

Phil H

Plus one for Molasses. Works a treat if a little slower than electrolysis but a heck of a lot easier to handle and nowhere near as invasive.

Ok I Know its an old post just looking to remove the light brown rust stains from some lathe parts. They aren't that bad that they aren't usable but it would be nice if could get them to look like new.

Couple questions :-

Is this likely to do the job and is it just soak or does it need the electrodes?

Is there better solution?.