Rust and how to remove it.

[John Stevenson 1Participant @johnstevenson1]

Dropped a file in today for 1/2 a day, doesn’t look any different but it does cut a bit better, mind you it was a crap file anyway.

 

Need to get one that’s worth doing and not one with bald patches [ like it’s owner <g> ]

 

Never though about files, thanks for the nudge..

 

John S.

[TendorParticipant @tendor]

Hi David,

The steel will emerge from the vinegar (after a rub with a cloth under the tap) with a matt grey appearance and so I’m guessing some minor etching occurs. It needs to be washed immediately as the surface is active to air. Some etching is not really a problem to me since the rusty item has already had its surface compromised. Mostly it will subsequently be machined or painted anyway. The larger rust falls off in flacks, as does the mill scale.

The items are fully sumerged. I have a collection of old plastic containers for the job. For example, a file or large drill could be submerged vertically in a soft drink bottle. The vinegar is poured in after placement and decanted back into its own container afterwards.

I’ve used this for many years but I vaguely recall reading of it in an old ME mag from maybe the 1970’s? As I recall it advocated a solution of table salt in vinegar. I tried that but later dispensed with the salt as it seemed to make little difference.

RDE

 

[IanTParticipant @iant]

Since I cannot see anyone else has mentioned it here – i will add that I like to use tea-bags to de-rust small things.

 

An old ice-cream tub, add 4-5 tea bags (I often re-cycle old ones) then add hot water to make your ‘brew’. Pop in the object to be treated and leave it overnight. The “tea” will turn black and the rust will wash off under the tap. If it’s not as good as you want – tip the old solution away and make a fresh brew and repeat.

 

For very heavily rusted parts, a solution of kitchen soda (in a bucket or bowl – I’ve also used window planters for longer bits) can be used with a battery charger to remove the rust with minimal loss of metal. The object to be treated is conneced to one connector and the other one is connected to a steel sheet – the two objects must not touch or short out. Not sure how or why it works but it does…

[Sub MandrelParticipant @submandrel]

I have an old engineering book that has advice on file re-sharpening. Various nasty acids (mixtures of sulphuric and nitric), but the tip is to take them out of the acid after a few minutes, wipe the acid off the tips of the teeth and let the acid etch the teeth a bit deeper, leaving the tips in place.

 

Another technique uses a complex formula, and you put the files in at an angle so a deposit builds up on the backs of the teeth to protect them, while the underside etches away.

 

Neil

[adyParticipant @ady]

Does the vinegar etch into the metal or just dissolve the rust?

 

It turns rust into a kind of goo which scrubs off by hand(I wear marigolds), metal itself is unaffected.

I’ve dunked cast iron and steel parts up to 2 weeks in it, too busy or lazy to take it out.

Buy 10 litres for about a fiver at tesco kinda thing and fill a bucket up with it.

Big long flat bits like my topslides were done in a gardening tray.

Cover parts 100% to keep any oxygen away.

 

One old calibrated dial came out lovely, while its brother was too worn to be useful, any pitting is also exposed.

A quick scrub with a stiff plastic brush tells you the extent of penetration.

All those old guffy pultra parts in my album got done this way.

Rinse with water, dry thoroughly with paper towels, then I oil it all over to protect it.

 

It doesn’t seem to evaporate completely either, I’ve had half a bucketful sitting in my garage for 6 months so far.

It IS an acid so I presume even vinegar will literally eat any metal which is left too long in the solution.

The big advantage is you can take your time with it and get a good result.

Just check the progress daily, top up any evaporation on longer jobs with more vinegar.

Saves a LOT of effort where rust is concerned, seems to be very effective, and is safe.

It also eventually eats your marigolds

Edited By ady on 21/07/2011 22:17:48

[MikeParticipant @mike89748]

Interesting that a dip in acid will sharpen a file – I shall have to try it with the collection in my scrap metal bin. That’s how many fish hooks are finally sharpened. A fish hook starts off as a straight piece of soft steel wire, which is first ground to a needle point. It is then barbed, bent to shape, hardened and tempered, then tumbled for cleaning. Most of these processes tend to blunt it, so a final, controlled, dip in acid restores the sharpness of the point

[David HanlonParticipant @davidhanlon38496]

Interesting topic. Typically I have used the battery charger/electrolysis method for derusting which has been very successful on old woodworking tools and a somewhat mistreated drill chuck (teenage son left it out in the rain for weeks!).

 

Some points :-

 

1. I found electrolysis is SLOW (hours/days, not minutes) larger the lump, longer the time, but effective, and while there may be some pitting where the rust has been, there is no loss of metal otherwise.

 

2. Thoroughly dry and coat the item (I use WD40) as soon as you take it out of the bath. The surface is now very, very clean (i.e. no protection AT ALL) and prone to corrosion.

 

3. Dispose of the residual gunk carefully, rumour has it that it can contain some nasties (such as chrome) .

 

Dave

[JoParticipant @jo]

Tannic acid, better known as cold tea, is effective against the rust. It takes its time, about a week on a bad case, but is dirt cheap, hand friendly ( well it goes rather black after a week of doing its stuff and you may think otherwise of sticking your hand in), and it does not generate any nasty smells/fumes.

 

Jo

[JoParticipant @jo]

Forgot to mention….milk and sugar are not required.

 

Jo

[_Paul_Participant @_paul_]

Lol
 
Although im sure I read somewhere (poss Wiki) it said that tea dosent actually contain Tannic acid but Tannin?
 
Regards
 
Paul

Edited By David Clark 1 on 26/07/2011 21:54:20

[The Merry MillerParticipant @themerrymiller]

 

Digressing for a moment, does anybody know the best way to remove a thick coating of Tannin from the inside of my tea mug. My wife won’t touch the mug anymore.

 

I tried putting it inside a powerful Ultrasonic cleaner the other day but although it was working it was taking ages to move just a tad, there must be a quicker way, like quick!!

 

[David Clark 13Participant @davidclark13]

Hi There

Ariel soap powder and hot water will do the job.

regards David

 

[The Merry MillerParticipant @themerrymiller]

 

Thanks David, now to find some Ariel powder.

 

[KWILParticipant @kwil]

As will dishwasher powder and boilng water clean the tea stain from a mug/cup.Tannin is also used to “treat” the water in steel boilers to reduce rusting, it appears to coat the steel surface.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, an over night soak in a solution washing soda should clean it, will clean out the teapot nicely as well, without the need for too much elbow grease. Just give it a good rinse next morning, and repeat if needed.

 

Regards Nick.

[_Paul_Participant @_paul_]

The school of thought from my neck of the woods is that you never cleaned the teapot as it destroyed the flavour

 

(apologies for the ot post)

[WALLACEParticipant @wallace]

It’s a balancing act really – the mug has to be dirty enough so that no one else will want to use it – but not so bad that things are growing in it ….. …

W.

[Sub MandrelParticipant @submandrel]

One observation on the electrolysis approach that makes it different from the others is that it is a COMPLETELY different process. There’s a mechanical component that removes loose rust, but the clever bit is what all those hydrogen radicals do – yes ‘free hydrogen’ which is present in a reasonable concentration at the metal before it can form H2 (di-hydrogen). Now that hydrogen can get in the metal and cause hydrogen embrittlement, which may be an issues in some critical applications… but free hydrogen is reactive and can reduce Iron 3 to Iron 2, converting horrible soft brown rust, iron 3 oxide with lots of water in it (Fe203.lots of H20) to hard grey haematite (iron 2 oxide) (Fe0). Losing the water means it takes up a similar space to the original iron, meaning the dimensional changes are reversed, and that ugly orange/brown stain becomes a hard, grey paitna. The rust is replaced with something less objectionable, rather than removed comletely.

 

OK my 30-year old a-level chemistry may be a bit dodgy, but you get the idea!

 

Neil

 

 

[Chris TriceParticipant @christrice43267]

I just use the bottles of rust removing fluid available from Halfords. All you do is dilute with ten parts water to one part fluid (shhh!! I use six to one) and plop the item in overnight. It’s absolutely brilliant and no trace of rust left whatsoever. If you do get a stubborn patch, give a little scrub with a fine wire brush and leave it a few more hours. Amazing stuff. I’m actively going around the workshop looking for things to de-rust.

[Clive HartlandParticipant @clivehartland94829]

There was a Mutiny in the Navy because the Higher ups wanted all the tea ‘Fannies’ polished bright.

The Matelots mutinied and the order was reversed.

They said that the tea tasted different when made in a polished tea urns and that it only tasted right in an urn coated with Tannin!

Another bit of useless information for you.

 

Clive

[Roger BrealeyParticipant @rogerbrealey95635]

I clean my mug with ordinary household bleach diluted as necessary (depends how thick the coating is) and left to soak overnight. Rinse out with boiling water before use.

[Clive HartlandParticipant @clivehartland94829]

If it does that to a mug what is it doing to your teeth?

 

Clive

[londonben10Participant @londonben10]

I have some rusty old lbsc design locomotive castings, in fact there are two complete chassis for live steam models. One is at 2.5″ gauge and the other 5″.

 

I’m thinking of using the halfords rust remover (Hammerite?) method …..

 

Is there a risk that the parts may lose metal beyond the tolerance of the specification, can anyone please advise?

 

Thanks in advance.

[russellParticipant @russell]

I’ve just been trying a product called ‘Evapo-Rust’ – it is apparently a chelation process, non acidic, entirely safe. It claims to not remove any metal, only what is already oxidised.

 

It appears to be very effective, cleaning up a small setsquare, some pieces of machine knitting accessory ‘linker’, and also some meccano. It leaves a slightly dull surface apparently suitable for painting.

 

Its a US product, available there and Australia at least, not sure where else.

 

hope this helps.

 

russell

[Phil PParticipant @philp]

Posted by russell on 31/08/2011 04:37:41:

I’ve just been trying a product called ‘Evapo-Rust’ – it is apparently a chelation process, non acidic, entirely safe. It claims to not remove any metal, only what is already oxidised.

 

It appears to be very effective, cleaning up a small setsquare, some pieces of machine knitting accessory ‘linker’, and also some meccano. It leaves a slightly dull surface apparently suitable for painting.

 

Its a US product, available there and Australia at least, not sure where else.

 

hope this helps.

 

russell

I posted about this product on 16/07/11

I have used this for removing rust from antique musical box combs.

 

http://www.evapo-rust.com/

 

You can buy it in the UK here.

 

http://www.musicanic.com/Supplies.htm

 

Phil

 

 

 

 

 

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