Vinegar as a rust remover

Re: Vinegar as a rust remover

Pam Niedermayer - Austin, TX

>I first tried vinegar (plus a little salt) about 7 years ago, and found that no metal was harmed except the blued metal found on things like Stanley squares. It's much less of a hassle than electrolysis.

Pam

Re: Vinegar as a rust remover *LINK*

Gary Roberts

>Industrial strength vinegar is used to clean electrolysis nodes, as well as dehumidifier coils. I've used it to clean very heavily rusted iron or steel... but the steel looked quite messy afterwards when all the pits showed up. But at least the tool worked again. Just make sure to thoroughly rinse the tool of all vinegar and dip it in WD-40 quickly. Another alternative is to dip the cleaned tool in alchohol if you can get full strength stuff... the ETOH replaces the remaining water. Just don't add an olive, stir or shake.

Gary


http://www.toolemera.com

Re: Vinegar as a rust remover

BobStrawn

>The water remover that they sell for gas tanks is reasonably pure denatured alcohol. The cheap stuff works fine for absorbing water. To stop the vinegar acid process, I put some borax in water and stir the tool around in that.

Bob

Need clarification here

Denis Ch�nard, Orl�ans, Ont.

>It is my understanding that most acids will dissolve rust, but will also eat at good metal if the tool is left for too long, whereas electrolysis stops when the rust is all gone, and the tool can be left for a week in the electrolysys bath without harm for the tool.

Do I understand this right?

DC

Re: Vinegar as a rust remover

Frank D. in Montreal

>Hi Todd,

I've been using vinegar for several years, and it does work well. The only caveat is not to let tools soak for too long (a week, for example) much like with citric acid. Even slight surface rust seems to cause a reaction that can eat away good metal, making pits even bigger. I've observed this more than once (with citric acid too), good metal being eaten away where there was only surface rust, while metal next to that with no surface rust was left totally intact.

Re: Vinegar as a rust remover

Michael Recchione

>I like the balsamic vinegar better than the white (I recommend Modenaceti brand), with some extra virgin olive oil, a clove of garlic, crushed and chopped, salt, pepper, parsley, basil & oregano. Oh wait! I think you're talking about something else... :-)

you are correct

Bill Tindall, E.TN

>Acetic acid (vinegar) dissolves the rust and some unrusted metal as well, especially if the object is left in the solution longer than necessary. Electrolysis converts some of the rust back to a less rusted state and blasts loose rust off as a result of the hydrogen bubbles formed. Unrusted metal is not affected by electrolysis, probably (see below).

There is the issue of hydrogen embrittlemnet in electrolysis. Hydrogen can diffuse into the metal and if it does it can cause the metal to become brittle. I have never heard anyone complain that this occurred so maybe it is a theoretical problem and not a practical one. To lessen the chances of hydrogen embrittlement don't use more current than necessary and don't leave the current on longer than necessary.

Thanks!

Denis Ch�nard, Orl�ans, Ont.

>

Re: you are correct

Stephen Shepherd in the State of Deseret

>Bill,

You wrote:

'I have never heard anyone complain that this occurred so maybe it is a theoretical problem and not a practical one.'

I experienced what I think was hydrogen embrittlement on one of the first hand saws I ever used in the electrolysis bath. I did not take the normal precautions and snapped off several teeth before I realized something was not right. It ended up being several fine card scrapers.

Since then I have either cooked the piece to 220 or sat it in the sunlight for the same period of time it was in the bath. No more problems.

Stephen

hydrogen embrittlement

Bill Tindall, E.TN

>From what I have read on the topic, it is not reversable. Once the hydrogen enters the metal structure it causes micro cracks which in turn makes the metal brittle. I am going to have the opportunity to chat with a metallurgist in the next week or so and I will find out what I can.

I bought a saw and when I tried to set its teeth some broke off. I concluded some saws just have brittle teeth.

Hydrogen embrittlement mechanism in simple terms

Andrew F in Australia

>Hi Bill,

Hydrogen atoms are very small.

In a metal, they diffuse to areas where the atomic structure is missing an atom or several, but notably, small voids/pores in the structure.

THey build up in here until they've formed a gas at very high pressure.

The high pressure in the void acts to help 'blow' the metal apart under the slightest stress -> embrittlement. As well, the hydrogen atoms tend to act to stop the metal from deforming (once again, embrittling it.)

There's a lot more to it, but this is the duck's guts of the mechanism.

CHeers,

Andrew

ps: reversible at a cost.

Andrew F in Australia

>Hi Bill,

Forgot to say, you can get hydrogen out, but it involves holding it at a temperature of 400 degrees Centigrade or so or a week in an inert gas environment, (or, if you don't care about scaling, in air.)

This has a habit of making the steel quite soft.

CHeers,

Andrew

Re: ps: reversible at a cost.

ThomD

>Can you coment on whether hydrogen enbrittlement is likely in this process? When I did it the gas just bubbles righ up off the surface, how does it get in the metal during the process?

Is H2 embrittlement a problem in electrolysis.

Andrew F in Australia

>Hi Thom,

I've never had to deal with hydrogen embrittlement in my working life other than making removing hydrogen from slabs of steel 10" - 16" thick and weighing 20 tonnes.

So, the following is purely supposition and an edjumakated guess that may or may not be right. I'll do it as dot points in a stream-of-consciousness type response that further underscore it's nature as a guess.

Hydrogen atoms are very small

Hydrogen atoms are what are in acid and cause the reaction.

At the Cathode (negative,) two hydrogen ions combine to form one molecule of hydrogen gas.

There is a presence of acidic hydrogen at the cathode.

It is also possible that the hydrogen attacks the metal instead of forming solution.

An atom of hydrogen sitting on the surface of the steel has two options:

... force its way into a tightly packed metal surface (into which it fits easily) or;

... float off into the water.

I'd be guessing that most hydrogen floats into the water.

However, there would be localised acidic attack, particularly in cracks in the steel (google crevice corrosion for more info.) The more acidic it is (read: higher current,) the higher the rate of attack.

I'd be guessing that the overly treated items are breaking because of local cracks that have been enlarged/weakened by excessive exposure to hydrogen in its ionic (acidic) state.

However, it is a guess and it's also possible that there may be a mechanism that promotes redissolution of hydrogen into the steel that I'm not aware of.

Trust that this makes sense and is clear enough (it's been a long day here.)

Cheers,

Andrew

Re: Is H2 embrittlement a problem in electrolysis.

Chris Scholz

>So, Andrew, does this imply that heavily etched blades and chisels (such as very expensive wood-grain pattern tools) might potentially suffer from H₂ embrittlement, too? In fact that's what our Chinese master swordsmiths claim (they call it 1,000 years of experience and not H₂ embrittlement though).

Are there are "non-embrittling" etchants?

Thanks,

Chris

maybe. Trust the local experience here. *LINK*

Andrew F in Australia

>hi Chris,

I can't comment categorically as it's not something I've ever worked with directly. As I said - my response was as much guess and supposition as fact in this case.

Hydrogen tends to gather in voids/pores - does this mean that it gathers in pores located close to the surface? I have no idea.

Trust the gathered wisdom over my guess.

All etchants are corrosive by definition. If it isn't an acid, it's likely to be an alkali. Similar problems exist. Steel suffers a different form of embrittlement (caustic embrittlement) under prolonged exposure to alkali.

Alkali doesn't attack steel per se.

Cheers

Andrew


http://www.corrosion-doctors.org/Corrosion-History/Eight.htm

ps: note the reference between hydrogen & etching

Andrew F in Australia

>Hi Chris,

In the attached document, there's a basic reference to the fact that Hydrogen migrates into the metal during etching and as a consequence of cathodic protection (= imposed current = electrolysis.)

Cheers,

Andrew

Re: ps: note the reference between hydrogen & etch

Chris Scholz

>Thank you Andrew,

this is very enlightening!

Chris

Re: Hydrogen embrittlement mechanism in simple ter *LINK*

Wiley Horne -- So. Calif.

>A few notes from a non-metallurgist. In my working life as a water engineer, I was involved in one situation where hydrogen embrittlement happened to a buried steel pipeline. So I'll tell you what I picked up from the technical people in regard to hydrogen embrittlement.

Incidentally, this pipeline blew up under pressure, as a result both of the embrittlement (caused by an unmonitored impressed current cathodic protection system), and faulty system design for dealing with hydraulic transients.

Anyway, what I understand is what Andrew said in his 'ducks guts' post, and also what is said by Dr. George Langford in the attached discussion on OLDTOOLS. To wit: That hydrogen embrittlement of steel is not itself a corrosive process--it happens as elemental hydrogen migrates into the steel. How does this happen? Well, typically it happens when the steel is acting as a cathode in an electrolytic cell, in the presence of a watery solution which will provide electrolytes. An electrolysis bath is an example, and a steel pipeline buried in wet soil with an impressed current on it is another. Either way, the surface of the steel is yielding electrons (e-). The water solution is dissociating to yield hydrogen ion (H+) at the steel surface. The electrons are forced to combine with the hydrogen ion to produce elemental hydrogen (H). As Bill T. said, this is a vigorous enough action to 'blast' everything off the steel surface which is not bonded--hence the effectiveness of electrolysis. The monatomic hydrogen diffuses into the steel matrix and moves along grain lines, finding likely spots such as voids. But the steel need not be cracked--it's just that the hydrogen molecules are really tiny.

In electrolysis, you're essentially 'plating' hydrogen onto the steel.

My understanding is that, as the monatomic hydrogen (H) dissolves into the steel, it combines with the carbon (C) in the steel matrix to form methane gas (CH4). And it is the pressure of this methane gas in the steel matrix which causes cracks in the steel. Now Dr. George (see link below) says that the elemental H combines with itself to form hydrogen gas (H2) inside the steel, and that it is the pressure of this hydrogen gas (not methane gas) which causes the fracturing. I don't know which is right, or if each may be right under certain conditions.

In any event, Dr. George says that when you're done with the electrolysis, to remove the hydrogen by heating the steel to 200-300 degrees for a few hours. Incidentally, George Langford made numerous contributions on OLDTOOLS to the extensive discussions of electrolysis to be found there, and a search on his name will bring up some great nuggets of info--and they are highly readable, as all his accounts are.

Wiley


Dr. George Langford on electrolysis & embrittlemen

Re: Vinegar as a rust remover

Todd O. Cronkhite Maine Native, Presently Away

>Some interesting info on the subject of hydrogen embrittlement, but I have a hard time believing that by any damage is done to the tools that any one of us would zap in a 5 gallon bucket using a low voltage auto battery charger. I zap at 30 minute intervals, which in most cases is plenty. For extremely rusted tools sometimes they need a second 30 minutes. I suppose in more industrial sized applications this embrittlement could be a problem, but on such a miniature scale I just don't see it as a concern.

Am I wrong?

T.O.

correct

Andrew F in Australia

>Hi Wiley,

Thanks for the post.

The hydrogen combines to form hydrogen gas at very high pressure in the void - in the order of 1000bar = 15000psi. THis tends to blow the steel apart.

George has nailed the rest - I'm running on memory from a very long time ago.

CHeers,

Andrew

but beware the tempering effect

Andrew F in Australia

>OOps - forgot another point worth mentioning - another double post with apologies.

I temper quench hardened O1 at 180degrees C (350F) for one hour. Holding at 300F for a few hours, while driving out the hydrogen, is also likely to drive out a bit of the temper and make the steel softer.

Cheers,

Andrew

Re: Vinegar as a zinc remover

Stephen Shepherd in the State of Deseret

>I placed some zinc plated screws in a jar of vinegar and placed it by the wood stove. Thinking this may take a few days or a week, I was surprised to see the vessel making bubbles. Within a half an hour most of the plating was gone and in a few hours I washed the batch with excellent results.

The same process in urine took 4 weeks.

When the screws dried out they were all rusty, just what I wanted.

Stephen

any acid will work to remove zinc

Bill Tindall, E.TN

>the bubbles are hydrogen but you likely didn't make enough to put the wood stove at risk.