Metal Cleaning Using Vinegar?

I decided to clean up some old woodworking pins I needed to use, and began by using micromesh sticks, which gave a nice finish - some minor staining, but smooth and much better than before. After doing about 10 of 20 pins, I got bored, and decided to try the "White Vinegar" method that I've often head about, but never tried. I also had some Coca Cola left in a bottle, so thought I'd try that too.

I put some cleaned and rusty pins in the vinegar, same with coke. Nothing seemed to happen after 30 minutes or so of fiddling and wiping,so I left them for 24 hours. The result that the rusty pins were unchanged, and the clean pins were rusty. Same with the coke, but with the added disadvantage that everything was caked in sticky brown residue. Gently abrading the rusty items with a dishwashing pad made zero difference.

So..what was the issue? I've read so many accounts of cleaning parts with vinegar that it can't all be wrong? Have I fallen victim to an widespread internet hoax?

I was using Sarson's clear distilled malt vinegar, which is in fact shown on their website being used to clean a rusty cast iron pan, with apparently spectacular results, although the link to how to do it didn't work...it took me to a website advetising magazines on keeping chickens.

Cheers.

Apparently if you do use Cola for anything using a diet variant drastically reduces the stickiness and doesn't detract from the effect (which in this case appears to have been minimal...)

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It's a mild acid and the results are highly dependent upon the concentration of the vinegar, the exposure time, and the quality of the metal

and even half decent metal can get damaged if dunked for too long because when given enough time the vinegar seeks out and exploits any tiny imperfections and inclusions

So it's a suck-it-and-see cleaning route, requiring experimentation

My source for the vinegar method called for a saturated solution of salt in vinegar.

Tested with overnight soak of some rusty nuts it worked fine. That was my go-to for nuts, bolts and similar things to small or PIA to do mechanically for a fair number of years.

Drifted away from using it shortly after I built my new workshop. Couldn't be bothered with the precautions needed with a cid in the shop. Nowadays I do de rusting in the blaster or mechanically with the good wheel on my bench grinder. Nuts'n bolts I buy new, or make if weirdies, guess I've grown out of the "scrooge too far" mentality.

Generally anything to be painted gets a coat of Krust to pick up and dela with any left behinds.

Clive

I use the remaining vinegar from pickled onions. It is wasteful to use fresh. It is just acetic acid which is a benign acid so hand safe (in these dilute levels) It is important to keep the item well submerged as air causes more rusting. On delicate items I use it in preference to phosphoric acid my favourite. Steel only. Of course kids can play at cleaning copper pennies with it.

Don't add salt. Salt promotes rust. I think the use of salt is an old wives trick of using it as a mild abrasive for everything, like my mother always recommended salt for cleaning tea stains off china and I still do because it works but not by chemical reaction just abrasion,

Cocacola is a very expensive way of buying phosphoric acid. Much better to buy the real thing as it is available very cheap for setting the pH of swimming pools. It has the advantage of leaving a thin layer of phosphate as protection though that appears as a tarnish on things you want polished finish. BTW brush it on and wash off after 10 - 30 minutes, don't need to dunk it in a gallon.

OK thanks all. I've got some pickled onions, so might mix it 50/50 with the Sarson's stuff and try again on an old drill chuck I found.

My favorite is lemon juice . Tesco's sell big bottles for a quid . Buying several bottles at once gets questioned sometimes at the till , if that's all you're buying .. I just say i like pancakes , and they laugh

I seem to recall a daily scrub with rubber gloves and a soft toothbrush to remove residue and inspect progress

I don't quite understand the appeal of home concoctions when commercial products are available. Is it likely a mix of pickled onion vinegar and Sarsons will work as well as a commercial product formulated by a chemist with access to industrial chemicals?

Vinegar isn't completely bonkers as a rust remover, because it's mostly dilute Acetic Acid. But it's not particularly effective. It's a weak Organic Acid, in dilute form a food product, and not aggressive - it's safe. Vinegar is an effective cleaner because the acid cuts through grease, removes limescale and kills bacteria. Good for windows, glassware, kitchen worktops, refrigerators etc. The acid reacts slowly with many types of metal corrosion, some faster than others. Copper coins clean up much faster than rusty nails.

Home mixtures risk unexpected secondary reactions. For example, Vinegar might start by removing one form of rust, but after clean metal is exposed, go on to create another type. Rust isn't a single simple chemical. Timing may be critical or impossible to get right.

As far as I know commercial rust removers don't contain Acetic Acid. Mixtures of Oxalic, Phosphoric, and Hydrochloric Acids seem common. They don't stink! Oxalates are colourless, which helps remove rust stains. Hydrochloric Acid is much more active than Acetic, and Phosphoric Acid converts any deep rust left in the steel's pores into a hard impermeable layer. This phosphate layer helps stop rust bubbling out from under paint or electroplating.

Fizzy beverages are even less effective than Vinegar. They're mostly water with a weak dash of Citric and maybe Phosphoric Acid, plus Carbonic Acid until the Carbon Dioxide bubbles off. The flavourings and sugar are unhelpful and Carbon Dioxide positively encourages another form of rust.

The only home method I've been impressed with is br's "I get good clean results with a bucket of water, washing soda and a 12v battery charger."

Dave

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Yes me too. It’s so easy and unlike even mild acids doesn’t etch the surface. Washing Soda is 80p a Kilo in Sainsburys.

Bill

I think I understand you - A steel bucket with the rusty bits in it. Which polarity is attached to the bucket and what are you using for the other electrode?

I guess you could use any DC power supply such as those that power phone chargers, LEDs, DROs etc.

JA

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Think Bill would advise a PLASTIC bucket or container. For big jobs, a wheelie bin has been used.

Regards Ian.

Sorry, a bit slow on my part.

Edited By Circlip on 29/01/2022 12:33:43

So I put the pickled onion theory to the test yesterday - on an old drill chuck:



Mixed 50/50 with the Sarson's white vinegar, and left in a pot overnight.

After some scrubbing with a toothbrush, rinsing in detergent, the soaking in bicarb solution to neutrlse the vinegar, drying and coating with WD 40 to get rid of the moisture remaining in all the nooks and crannies, and buffing with a cloth, this was the result:



Probably slightly worse than if I'd spent probably 2 minutes with it against a fine brass wire wheel, which would have had the added benefit of not saturating ferrous metal in acid and water.

So after the woodworking pins, and this, my conclusion about using kitchen ingredients for removing rust is that it's highly time consuming waste of vinegar - unless the only tool you have is a toothbrush. Even then, if you substituted that for a brass suede brush it would be just as good if not better.

The household stuff bodge de-ruster idea is primarily about using what you have to deal with the odd rusty thing.

Getting any half way kosher nostrum has always been a bit tricky and invariably leaves you with a lot left over. Which will be a pain to store and quite likely to have gone off when you next need it again 5 years or so later. Having several DC power supplies around I picked up a bag of washing soda nearly 20 years ago "just in case". I may not live long enough to actually use it.

My blast cabinet does get run up on a fairly regular basis but few of the things I do would be worth putting in a soda tank.

Impossible to have the "proper everything" to hand.

Clive

PS Back in the day I got very acceptable results from overnight( ish) with the salt in vinegar saturated solution. No idea what i did differently to Dr_GMJN.

A very popular rust remover used in the old vehicle restoration hobby in Australia is Molasses. Sounds strange but I and many others have been using it for years and it works really well. Immersion in a solution of molasses in water (concentration does not matter) for a week or so will completely remove rust. I believe that the idea originally comes from America where it is a well-known idea amongst the gun restoring fraternity.

In Australia and the States, Molasses is widely available from the sugar-cane industry and is used in the cattle feed industry. It may be hard to get in the UK. Two possible sources are the Carribean/African food shops and maybe it is available from animal feed suppliers?

Golly mate, we go to the supermarket here.

JOHN, From what I have been told, molasses is not a common commodity in the UK. However with Britains growing overseas-born population it might be now. On the other hand you might be confusing molasses and treacle which I believe are not the same. I was born and bred in England and prior to covid used to visit regularly. Good to know that all the supermarkets are still there since I last visited 3 years ago.