Rusty tools and vinegar question

[Biker]

Dear Hivemind,
I have a friend (ahem) who has some rusty tools, some are deeply pitted with rust which I ... he bought at a bootfair recently. They're salvagable but the thought of spending ages wire brushing off the rust (even with electric grinder attachment) sounds like too much hard work when there's a possible simpler faster way of doing it would be most handy.

I read in a couple of postings that vinegar is a good solution to soak the tooks in. So what does this actually do, and does it damage the metal? I mean in a corrosive sence, or does it simply eat between the layers of rust and make them flake off easier using a wire brush later?

Any recommendations in this field would help me ... ah, my clueless mate lots.

Thanks in advance.

Moi

 

[Retired Member southey]

I haven't used vinigar, but i've reclaimed a few badly pitted tools just by giving a soak in three in one oil for a week or so the a quick attack of the wire brush and there back to a useable state, albeit in need of a sharpen.

 

[ged]

... [my friend] read in a couple of postings that vinegar is a good solution to soak [tools] in. So what does this actually do, and does it damage the metal? I mean in a corrosive sence, or does it simply eat between the layers of rust and make them flake off easier using a wire brush later?

Yes, it does eat some metal and yes, the metal can be damaged:

http://en.wikipedia.org/wiki/Pickling_(metal)

For your applications I'd imagine that you're going to be using weak acids on old tools, so the damage would be (a) minimal and (b) acceptable. I've often used household vinegar for cleaning rusty items with no ill effects. Using the vinegar (left over after eating one of my favourite foods, pickled onions) I've soaked (for a couple of months, because I forgot about it) an old hatchet that got lost in a bilge full of salty water. It needed no wire brushing to remove the rust but it was covered in soft gunk so I wire brushed it anyway. It cleaned up lovely and after 15 seconds with the bench grinder it was back to its old self.

You won't need to worry about things like hydrogen embrittlement unless you're building the space shuttle or something.

 

[laro13]

You could also do it with Electrolysis, it doesn't damage the metal.

for example:
http://www.htpaa.org.au/article-electro.php

Works great.

Cheers,

Jasper

 

[Woz888]

Soaking in a Molasses solution is a good was to remove rust by all accounts. Haven't tried it myself as yet but I have a few candidates lined up ready. See ->http://www.moreg.org.au/dissolving_rust.htm

Woz

 

[teknohippy]

I find white household vinegar preferable to malt vinegar for cleaning purposes.

 

[tombear]

I've had a lot of success with a strong hot citcic acid solution (brewing shops sell it, even Wilkinsons).

20 or 30 minutes soak normally does it but they will need a good polish after they are rinsed off as the metal does go a dark grey if it is left, even under oil. A couple of passes on a wire wheel does the job.

The blades on all these were treated so,

All from Accy flea market for a couple of quid the lot.

ATB

Tom

 

[FGYT]

if you use and acid you needo twash it off in something ot neutralise it or it will keep working even with water to wash off etc


i would see if any body has a grit blaster ir local garage etc its what i have doen to my blades after HT (well when Ben sorts it out )

ATB

Duncan

 

[Teepee]

Phosphoric acid is good, it'll work overnight.
Its sold as rust removing acid or brick acid.

 

[Adze]

I've had a lot of success with a strong hot citcic acid solution (brewing shops sell it, even Wilkinsons).

20 or 30 minutes soak normally does it but they will need a good polish after they are rinsed off as the metal does go a dark grey if it is left, even under oil. A couple of passes on a wire wheel does the job.

The blades on all these were treated so,

All from Accy flea market for a couple of quid the lot.

ATB

Tom

+1 for citric acid - most of the over the counter rust treatments have it listed as a substantial ingredient. They're expensive, by and large, though and for brewing it costs buttons, or less. IIRC I paid a couple of quid for a half kilo of crystals in my local brew shop/health food shop.

Let me know if you can't easily find it in France and I'll stick some in the post to you.

Cheers,

 

[Iron Hoarder]

If you just neutralize the acid and leave the black coating it actually acts as a rust preventative coating. I can't remember the chemical equation but it is a result of the reaction between the rust and the acid. it doesn't look bad after a rub with some oil.

 

[Harnser]

electrolysis cleaning
Another method which can be used, actual turns the iron oxide back into iron and lifts any crusting or concretion, involves using a steel tank (or plastic tank with steel plates lining)some weak caustic soda solution (washing soda and water) what you do is fill the tank with the soda solution hang the item to be cleaned so its insulated from the steel tank but submerged in the soda and then using a low voltage, low current dc supply say 12V dc 50mA connect the anode +ve to tank/plates and the cathode -Ve to the item to be cleaned (ensure all separate iron/steel parts of the item have a good connection to cathode ) and leave for severals hours, or days.
Ive had quite alot of success with this method, it cleans the item without removing any metal, frees up rusted moving parts, and leaves makers marks intact but does require patience. Its better to have low current for a couple of days to a week than blasting the rust (Iron oxide) off with too much current, the iron oxide is better converted back to iron slowly.
For your Safety there is plenty of info on electrolysis cleaning on the web and it would be wise for you to read up on it, water, chemicals, and electricity have their own hazards and more hazards when mixed.

 

[Biker]

Thanks for the replies chaps. The electrolisis method sounds really interesting, gonna have to look into that method a bit more, and the terminology and processes. I'm a wood butcher by trade, so you can imagine it's a bit out of my comfort zone.

Tombear, impressive results on those screwdrivers! That Stanley rachet driver at the top looks brand new!
Adze, thanks for the offer of the citric acid crystals. I'll see what I can source over here locally, the french are into home brewing but mostly cider and calvados. Beers are a bit down on the list I suspect. Anyway I'll give it a go.

FGYT, thanks for the tip about neutralising any acid treatment properly Will bear that in mind.

Thanks again.

I bought a froe recently for £4 at a bootfair in the UK, it's a small one, only 7 inches long but the iron looks good despite the rust, so I thought I'd give it a clean up and see if I can resurrect it. Not sure if it'd get a use as I'm a hatchet man rather than a froe user, but you never know what use I could get out of it.

Ta ta.

 

[tombear]

Cheers! I must admit going a bit anal retentive on the top one with the buffing wheel. Apart from a even coat of fine rust all over the blade it didn't look used!

I've a pretty complete set of in and out canal goose neck gouges by I Sorby to do up sometime, came out of a Pattern makers chest at Burnly Flea. Far too good for my skill level but what the hell!

I'm leery of the electrics myself but will get around to trying the electrolysis thing, a mate whos a gunsmith in NZ gets fantastic results from it.

ATB

Tom

PS whats the best thing for neutralising the acid?

 

[ged]

The blades on all these...

Get out of my toolbox!

 

[ged]

... would see if any body has a grit blaster ...

Test it on something disposable first. Some blast cleaning methods are very aggressive and can leave the surface badly pitted. The people who operate the equipment will probably know if you ask them, but they might assume that you do as well, so it's best to ask.

 

[ged]

... I bought a froe recently for £4 at a bootfair in the UK, it's a small one, only 7 inches long but the iron looks good despite the rust, so I thought I'd give it a clean up and see if I can resurrect it. Not sure if it'd get a use ...

If you can't find a use for the froe, I can.

... as I'm a hatchet man ...

I always thought there was something.

Last time I looked into electrolysis I think the current density needed for gentle cleaning was in the order of one milliamp per square centimetre (ten amps per sqauare metre). Don't get carried away or bad things will happen and try not to get too creative with materials or unexpected (probably also bad) things will happen too.

You'll usually want to try to get a fairly uniform current density over the whole surface, and electric current tends to take the path of least resistance. So with something like a froe which is basically just a couple of flat surfaces it shouldn't be too difficult, but with things that have a lot of shape, for example something like an auger bit, it could be harder.

Somewhere I have a bunch of useful links on this topic but I think they're still awaiting cataloguing. I googled "rust removal electrolysis" (without the quotes) and came up with nothing I recognized but this looks useful, the guy has obviously put a fair bit of work into the setup and shows good results on a fairly awkwardly-shaped example.

 

[ged]

... whats the best thing for neutralising the acid?

I'd use bicarbonate of soda or something equally mild. When it stops fizzing, you're done. Stay away from strong alkalis like caustic soda unless you're confident of handling them, they can burn skin and damage fabrics as badly as strong acids. Acids tend to eat steels but alkalis tend to preserve them, so it's better to get rid of all traces of acid. Washing with water will just dilute the acid unless the water is slightly alkaline. Rain water will usually be slightly acid because of dissolved carbon dioxide. The pH of your tap water depends on where you live, i.e. what rocks have dissolved in the water on its way to your tap (pH is a measure of acidity, scale about 0 to 14, where pH 7=neutral, lower pH=acid, higher pH=alkali).

The other thing to avoid is strong solutions of most salts, you've probably seen how much damage a common salt solution does to vehicle bodies and sea-going boat parts.

 

[Adze]

Excellent link ged - looks like a winner! FWIW a fermenting bin similar to the one it looks like he's used costs under a tenner from Wilkinsons. I might treat myself to a new one for beer and use my old 'un for this. I've got loads of old HP and Epson printer power supplies from the last 20 years or so which can easily supply a low voltage and current until they burn out

 

[tombear]

Cheers! We have anyamount of bicarb'.

ATB

Tom

I'd use bicarbonate of soda or something equally mild. When it stops fizzing, you're done. Stay away from strong alkalis like caustic soda unless you're confident of handling them, they can burn skin and damage fabrics as badly as strong acids. Acids tend to eat steels but alkalis tend to preserve them, so it's better to get rid of all traces of acid. Washing with water will just dilute the acid unless the water is slightly alkaline. Rain water will usually be slightly acid because of dissolved carbon dioxide. The pH of your tap water depends on where you live, i.e. what rocks have dissolved in the water on its way to your tap (pH is a measure of acidity, scale about 0 to 14, where pH 7=neutral, lower pH=acid, higher pH=alkali).

The other thing to avoid is strong solutions of most salts, you've probably seen how much damage a common salt solution does to vehicle bodies and sea-going boat parts.