Thread: Yet Another De-rusting Method

I used to use vinegar almost exclusively until I tried citric acid. That's my go to solution now. I will use electrolysis for the big stuff though. I think citric acid has more grunt.

TT

The vinegar derusting method has been mentioned before and is as old as they come. While it is very gentle, as are molasses and citric and other weak acids, if you forget to attend to it, it will still eat away metal whereas electrolysis will not.

The WD40 addition afterwards sound good but it is not if you want to eventually paint it as the WD40 needs to be very well cleaned off (especially in crevices etc) or it will really mess up most finishes.

Once the chunky rust is taken off using electrolysis I actually let the objects develop a fine patina of rust and then paint weak phosphoric over that patina. This converts the patina into iron phosphate which is rust resistant. Then I dry the objects thoroughly in a BBQ oven at low heat and they easily take a painted finish that lasts. If you apply the phosphoric acid to the chunky rust you end up with lumpy iron phosphate whereas electrolysis will remove this but removes no metal underneath.

I'm with Bob on this, although I haven't got an electrolysis bath set up at the moment. I generally use brown vinegar, seems to be stronger than the white but it may just depend on the brand etc. I like molasses too but somehow the whole workshop ends up sticky

Originally Posted by Claw Hama

I'm with Bob on this, although I haven't got an electrolysis bath set up at the moment. I generally use brown vinegar, seems to be stronger than the white but it may just depend on the brand etc. I like molasses too but somehow the whole workshop ends up sticky

Yep - it's brand or more source dependent.

A few excerpts from Wikipedia;

Vinegar is typically 4-18% acetic acid by mass. Table vinegar tends to be more diluted (4% to 8% acetic acid), while commercial food pickling employs solutions that are more concentrated.

and White or spirit vinegar

The term "distilled vinegar" is somewhat of a misnomer, because it is not produced by the distillation of vinegar, but rather, by the fermentation of distilled alcohol. The fermentate is then diluted to produce a colorless solution of about 5% to 8% acetic acid in water, with a pH of about 2.4. This is variously known as distilled spirit or "virgin" vinegar,^[6] or white vinegar, and is used for medicinal, laboratory, and cleaning purposes, as well as in cooking, baking, meat preservation, and pickling.^[7] The most common starting material in some regions, because of its low cost, is malt. In the United States, corn (maize) is the usual starting ingredient for most distilled vinegars, such as Heinz.^[8]

Brown vinegar is usually made from Malt

Malt vinegar, also called Alegar, is made by maltingbarley, causing the starch in the grain to turn to maltose. Then an ale is brewed from the maltose and allowed to turn into vinegar, which is then aged. It is typically light-brown in color. In the United Kingdom, salt and malt vinegar is a traditional seasoning for fish and chips, but any commmercial fish and chip shop will use non-brewed condiment - 3% acetic acid coloured with caramel (burnt sugar)

Well after another 14 hours in the vinegar I pulled the squares out and rubbed them with steel wool.It seems gentle enough and I was able to get past the surface rust and the blades are back to a blotchy silvery steel colour.

Anyway I rinsed them in water then dried them in the oven (good idea Bob). Do you know...they already have a cloudy discolouration, albeit faint, of rust.

The process has revealed inch graduations on the blades even though they are faint.
To remove the surface rust with a wire wheel or linisher would not have revealed the graduations because I am sure they would have been rubbed away.

I will try coating them in a wax from our sponsor and hopefully they will be happy working for me.

I find it fascinating just how effective methods can remove rust so easily.

The picture is of the 2 squares after a total of about 30 hours in straight "No Name" white vinegar. I need a large flat tray to soak them in so I used an old tool box with a piece of clear plastic as a liner

G'Day to all.
Probably my experience will be helpfull.
Of course I have an oven. But right now here in Ukraine is a summer, so using oven for driyng any pieces after citric acid (I prefer this) or white vinegare makes the temperature in the kitchen high. We have now 32C day's temperature.
Probably now Aussies can turn up ovens because this is winter there.
But I prefer rinse any metal parts after citric acid and immediately dry them with my wife hair-driyer.
The effect is the same but the temperature in my flat is lower than I use an oven.
Of course, after drying I grease (usually plane blades or plane parts) with hand oil like Johnson Baby's oil. Of course stolen from my wife too

Originally Posted by snikolaev28

G'Day to all.
Probably my experience will be helpfull.
. . . . . . immediately dry them with my wife hair-driyer.
. . . . . . with hand oil like Johnson Baby's oil. Of course stolen from my wife too

I definitely want to know how you steal all this stuff from your wife!

Your choice of method can also be relate back to the condition and needs of the process.

Electrolysis will remove any paint on outside surfaces or japanning. So if it is collectable and you want to retain the original finish not a good idea. Molasses will leave the paint on, I assume vinegar also.

Electrolysis tends to work unevenly, it affects the outer surfaces more and sometimes doesn't get into small cavities, holes, nooks and crannies and also apparently can crack the metal or create structural weaknesses in the metal buy changing the stresses. Don't use S'Steel with this process it produces toxic gasses.

Molasses is messy but is quite safe & non toxic, creeps into all the tight spots. You need to use Farm Grade Molasses with the sulphur for good results not the stuff your wife uses for baking. It will react and damage non ferrous materials. It is reusable but it may ferment and stink up the place. Can be used as a nice fertiliser at the end of use.

I have also read that boiling the parts in a pot with the vinegar speeds up the process.


All methods promote flash rusting as soon as exposed to the air.



A summary of info I have gathered about the place.

snikolaev 28
Its a very brave man who messes with the wife's things. Very brave/game man indeed.
Just don't get caught

DSEL74
You have summarised my thoughts very well

I spent the day dismantling a Dawn Post Drill and have put the parts in molasses baths so if anyone is interested I can post some results in 3-4 weeks.

On the sad side I broke the main casting during disassembly. I wonder how much it would cost to have recast? I think welding cast iron is a major hassle to do correctly.

Originally Posted by snikolaev28

Of course stolen from my wife too

We are all worried for you because we are picturing this ...

Hi Rod, I've also used vinegar, but found Citric acid more effective, and significantly cheaper, because I bought it in bulk for about $5/kg as I recall. The vinegar I used was the floor cleaning type which is cheaper, but not necessarily stronger.

You can neutralise the acid (either type) pretty quickly by using a Baking Powder solution, but this won't stop the slight rust bloom (so I don't bother - just a damn good rinse). That freshly exposed steel just loves to get it on!

This is thread I put up a while ago on CA.
https://www.woodworkforums.com/f152/r...p-step-159033/

The grey coating that either method yields is a very slight measure against re-rusting. Nobody has yet nailed exactly what the compound is, but the best suggestion yet was Pearlite.


Btw, in the Saw Files thread I put this link:
http://www.wkfinetools.com/hUS-saws/...History-ne.pdf
which is the history of the file, published by Disston.......who also had a range of files. In fact (IIRC) it was them that created the Saw Sharpening Files as we know them because Nicholson didn't have anything suitable.

Originally Posted by pmcgee

We are all worried for you because we are picturing this ...

Chill out brother - Mama's only got a stick of Baltic Pine there, whereas the Good Ole Boys clearly have a log of Hickory.

Just to add one slight variation ...

In an ususual move for me, I saw something to bring home when there was a roadside collection going.

It was a toolchest I suppose ... all in a nice pine (suspecting oregon, hence triggering my radar) with dovetails ... say no more.

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It is lined with tin? which is nailed in all-over.
And there were some super-rusty lumps of coral in the bottom that were once the hinges and some other bits.
As I was tipping the rust into the bin I started by congratulating myself on at least minimising the extra projects scrounged responsibly retrieved to just the chest ... and yet after a second I was thinking "Well ... they are probably the right hinges for it ... ummm ... maybe I could experiment ... ummm ..."

And so the hinges were retrieved from the bin.
I had never contemplated cleaning up anything this rusty before, but figured to try the vinegar thing and see what happened ... "Nothing to lose".
One little snag ... no vinegar in the house.

Well ... I was definitely drawing the line at travelling the 5min down the road to the deli and back!

I did recall that before which switched to what turned out to be phosphoric acid to clean the salt chlorinator of barnacles, we had hydrochloric acid for the job. Some of that still around. Hmmm ....

I might have looked up some vinegar on the internet to see what strength it usually was ... or else guessed.
The HCl is 320g/L so say a third ... and I figure to add 100ml to 1L of water.
And added the rust.

Bubbles started pretty quickly, so I set the timer for an hour. When I retrieved the pieces and washed then off and scrubbed a bit with a wire brush I couldn't believe the change. I didn't take a before photo (doh) but I think you can imagine it from these photos at the 1hr mark.

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I gave them one more hour and ... wow!

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Rinsed, dried, and used WD40 and got them moving again ... then slathered with Oil of Sheep.

I never expected such a result.

Cheers,
Paul

I forgot ... when it settled ... the residue ...

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