Vinegar & Citric Acid Rust Removal Questions ?

[Thomas Nye]

I have cleaned my vintage saws and other tools with WD40, 0000 steel wool, 7447 scorchbrite for years. I have recently read about the vinegar rust removal method as well as citric acid.



Can you guys explain the process in detail as I would like to try it.

how long to soak ?
how well does it work ?
any before & after pics ?
I have tried chemical rust removers and was not impressed. Any info would be greatly appreciated.

[Jim Koepke]

I am not real sure of the chemical reaction details, but a weak acid like vinegar or mild citric dissolves rust but not the harder steel or iron.

I usually use citric acid since it is cheaper to mix up your own when you can find the powder.

I usually soak about 24 hours.

Here are some pictures, one before and two after:

149675149676149677

It does a fairly good job, just rinse and towel off. A little steel wool or abrasive paper will shine it up a bit more. The face of the frog was lapped after the derusting.

jim

[Thomas Nye]

WOW, that looks great. Does it affect the paint on the inside of the plane, or does it only attack the rust ??? Now I cant wait to try it.

[Ron Petley]

It does not seem to do anything to the paint if you do not soak it for days.
If you scrub it with a toothbrush or something as you go along it speeds things up. It does leave a bit of a greay coating on the metal that will make your fingers black, but you can wipe this off after soaking.
Cheers Ron.

[Andrew Gibson]

I just finished soaking a Millers Falls block plane that was best referred to as a ball of rust. I ended up soaking it for a good 30 hours in vinegar. What was left of the original paint was still there after the soaking. I ended up painting the appropriate parts with some black Rustoleum and it looks pretty good now. I still need to finish flattening it, and eventually get a new iron for it as the one I have is severely pitted, but now rust free.

[David Cefai]

I have used Di-Ammonium Citrate successfully for rust removal. This is Ciric Acid 66% neutralised with Ammonia.

The way it works is to "chelate" the rust rather than "attack" it as neat citric acid does. The advantage is that it is even less aggressive to iron while bring almost as fast acting.

Best I can offer is: If you tell me the ammonia strength I'll calculate the proportions to mix.

[Peter Bell]

While I am just getting my head around all this I think it is important you have as much information laid out on the desk so you can make an informed decission on which way to go.

I am experimenting at the moment with the following products and processes.

1. Ordinary vinegar
2. Cleaning Vinegar
3. Citric Acid
4. Combination of Vinegar and Citric Acid.
5. Mollases
6. Phosphoric Acid
7. WD40
8. Steel Wool


And my favourite depending on the application
9. Electrolysis


My research so far suggests that Vinegar and Citric Acid actually etch the material it is working on. This has an advantage when we are trying to restore old files and rasps and I am led to believe it can even make some of the newer ones even sharper.

I like electrolysis for doing up old saw blades and have had good success with dipping an iron plane in the process.

From what I have read most people have their favourite and some defend it to the death. I tend to think that each case should be taken on its merits and then choose the one that in your opinion best suits the problem.

As I am still researching and learning I like to follow any information I can get and not have a closed mind.

I hope this thread goes for a bit longer so I may glean some more useful insights.

Peter

[jerry nazard]

Let's not forget Evaporust.

[Jim Koepke]

Peter,

I have never heard of using molasses. Have you tried it and did it actually remove rust and not leave a sticky mess?

My experience with WD-40 and steel wool is that both required a heavy application of elbow grease to work.

I like effective, cheap, ecological and easy to clean up. I do not know that one method is any better than the others though I do suspect that electrolysis works better than some.

Citric acid has worked pretty well for me so far. Now that I live in the Northwest a new source will have to be found.

jim

[Paul Ryan]

I usually soak in vinegar over night and then into the day. Probably 16-24 hours. After removing I scrub what I can with a scotch bite pad, stainless steel toothbrush, and the larger areas with a scotch disc on a die grinder. It works real well the scotch disc will take the rust off with out the vinegar soak but it requires a lot more time. I have not had the vinegar cause any problems with the paint it shines up the brass and does a nice job. I have never tried citric acid. Some one here recommended vinegar, I bought 2 gallons from walmart for $3. I never looked for citric acid because the vinegar has worked so well for me.

[Thomas Nye]

My current method is to scrape down the blade with a razor blade, then a heavy dose of WD40 & either 0000 steel wool or 7447 red fine scotchbrite. I find scotchbrite does a better job and is quicket too. It does indeed take alot of elbow grease and in my experience it is effective...........I had read about the vinegar & citric acid and wanted info on this process. At the current time, I am mainly interested in it to clean vintage saws blades, though I have a Ton of planes that could use a bath as well. So all the info I can get will be helpful.
Thanks for the responces and info so far, I look forward to more. Thanks in Advance.......

[David Keller NC]

Thomas - Regarding the citric acid, here's a place to start - dissolve about one tablespoon of citric acid into about a quart of warm tap water. It should dissolve easily and quickly.

Immerse the part to be de-rustified into the liquid, and wait about 30 minutes to an hour. During this time, you should notice quite a few bubbles forming on the rusted part. Remove the part, rinse in warm tap water, and examine it. If it's still rusty (and was really rusty to begin with), then you may have exceeded the capacity of the tablespoon of citric acid (the chemical reaction "uses up" the citric). Just make another solution and repeat as before. Citric acid is perfectly safe at this concentration for your pipes and so is the iron citrate that's formed during the reaction, so just pour the used liquid down the drain.

One warning - if you wish to preserve the etch on a saw, do not use the citric, acetic (vinegar) and especially the phosphoric acid treatment - these chemical treatments will obliterate the etch on most saws. In such a case, scraping with a single-edged safety razor blade is the best option.

[Thomas Nye]

Thomas - Regarding the citric acid, here's a place to start - dissolve about one tablespoon of citric acid into about a quart of warm tap water. It should dissolve easily and quickly.

Immerse the part to be de-rustified into the liquid, and wait about 30 minutes to an hour. During this time, you should notice quite a few bubbles forming on the rusted part. Remove the part, rinse in warm tap water, and examine it. If it's still rusty (and was really rusty to begin with), then you may have exceeded the capacity of the tablespoon of citric acid (the chemical reaction "uses up" the citric). Just make another solution and repeat as before. Citric acid is perfectly safe at this concentration for your pipes and so is the iron citrate that's formed during the reaction, so just pour the used liquid down the drain.

One warning - if you wish to preserve the etch on a saw, do not use the citric, acetic (vinegar) and especially the phosphoric acid treatment - these chemical treatments will obliterate the etch on most saws. In such a case, scraping with a single-edged safety razor blade is the best option.

Thanks for the info. So, for saws I can see the etch, I will do my normal cleaning. But for some that are more pitted and the logo cannot be preserved, it should work great. I would love to see before and after pics of a saw being done. The process I use works pretty good, but I have read how good the other cleaners ( vinegar & citric acid ) work and I wanted to see if its a better alternative.

[Jim Koepke]

For a stronger form of vinegar, you could try photographic supplies.

Black and white photo stop is just a stronger form of acetic acid.

If you do not have at least a minimal understanding of chemistry and how to mix safely, it might be better to do some research before attempting this at home.

Remember that different grades of chemical supplies have different classifications for purity.

Photo grade acetic acid will not have the same type of impurities allowed in metal finishing grades which will be different than food grade and so on.

jim

[Kenneth Speed]

I've yet to try either citric acid or electrolysis but I've read that those methods aren't optimal for saw blades. I don't know why but I suspect it may have something to do with preserving the etching on the blade.

I've scrubbed some saw blades with a razor blade and fine abrasives lubricated with oil and it works but I'd sure be open to a less labor intensive method.

Vinegar mixed with a little table salt is a very old home made good brass cleaner that works well but I've never tried it on iron or steel.

I'm planning to experiment with some junk saws and citric acid in the near future.

[Prashun Patel]

I've used citric acid in as strong a solution as 25%. Etching becomes an issue with prolonged soaking. If take the piece out every 20 mins or so and scrub it, you'll know when you can stop.

The other great way to remove rust is mechanically: I chuck a fine wire cup brush in my drill press (or lathe) and then buff the oxidation and residual rust off. This works great on screws. Just wear heavy gloves.

[Jim Koepke]

The other great way to remove rust is mechanically: I chuck a fine wire cup brush in my drill press (or lathe) and then buff the oxidation and residual rust off. This works great on screws. Just wear heavy gloves.

And don't forget the eye protection.

jtk

[Jacob Nothstine]

I just stared using Simple Green and like it a lot. It's safe and works great. Here is a good web link.
http://www.wkfinetools.com/contrib/CiantiM/cleanSawPlate/cleanSawPlate-01.asp

[Mark Wyatt]

Over the last few years I've had reason to take the rust off many old tools. For heavy rust, I prefer citric acid as a chemical remover. The primary reasons are cost and flexibility. Citric acid powder can be purchased very cheaply from any homebrew supply location. A Google search for homebrew supplies will lead you to multiple websites where the powder can be purchased for $4-$5 per pound. That will easily make 10 gallons of solution. The powder is easy to store. The powder allows one to make different concentration of solution based on need. The acid is very gentle on paint, although a long enough soak (like a week) will begin to remove the paint. One advantage of this approach over mechanical removal is that it will get into hard to reach places.

The acid does leave a residue which must be cleaned off. On the large surface of a full saw plate, this cleaning does take some time. Also, the raw metal will need to be quickly covered with a protective coat of some fashion or will quickly rust. Some other disadvantages of the acid learned from experience: items left to soak multiple days will begin to form crystal deposits from the citric acid which are harmful and difficult to clean. Solution left exposed for 4-5 days will begin to mold.

[Roy Griggs]

I use C/A almost exclusively for derusting. Several yrs. experience boiled down to cheapest/easiest least problems (for me) YMMV. I found that I can buy my C/A from a local industrial chemical supplier (Brainerd Chemical) in 8# tubs for about $25. With that amount I can make at least 16 gallons of derusting solution. Yes, I agree electro zapping is cheaper....but I find my C/A setup easier to use. C/A will clean the rust off a saw and a quick buff with a scotchbrite (I use green pads) will remove the gray residue, but it will not remove the stains which darken the saws.
I think that Wiktor still has a link on wkfinetools to my plane cleaning 101 for a short tutorial on doin' planes with C/A.

[Bill Houghton]

I use white vinegar (easy to find, easy to dispose of). For me, in order of your questions:

24 hours or so (not rigid, depends somewhat on the level of rust).
Pretty well.
No.

Immediately after removing the tools/tool parts from the vinegar, I rinse them thoroughly in running water to remove/neutralize the vinegar, then hit them hard with WD-40 to neutralize the water. Leaving out either of these steps sets the tool up for new rust, in my experience.

I've found long sheetrock mud pans (cheap plastic ones at any big boxy store) will accommodate planes up to jack plane length. If I had a No. 6, 7 or 8, I'd look at wallpaper soaking trays. I also made a vertical soaker from ABS pipe - pipe, with a cap glued on the end - for soaking long, thin stuff like bench rules. For small stuff, like block planes, I cut the top off one of the clumping kitty litter jugs that we had lots of when our kitties were the dominant life form in the house, although the mud pan works fine for that, too; I'm just cheap and look for containers that will hold the tool with no excess space that I have to fill with vinegar.

Vinegar's not terribly good at removing dead spiders and grease, so do that kind of cleanup first. Also, remove flaky rust physically - wire brush, single-edge razor - let the vinegar get down to the base faster.

Like all rust removal techniques, this cleans up a tool - it won't magically restore metal that's gone. But you probably know that already.





how long to soak ?
how well does it work ?
any before & after pics ?

[ray hampton]

vinegar will dissolve some water-based paint which got no business being on steel tools any way

[Jason Aldridge]

I tried soaking some 10" saw blades today for a few hours. Scrubbed with a brass brush rinsed the residue off and realized all of the labeling had come right off. It's a Forrest WoodWorker I, an older one but still surprised me.

[Christian Castillo]

+1 for electrolysis, after the initial set up, its cheap, easy, and very clean.

[Phil Mueller]

I use electrolysis also for larger items. I tend to leave it over night.

However, in the future I'll check it more often and pull it when it appears that most rust is gone.
Overnight will leave the piece absolutely rust free, but pretty black which then needs a Scotchbrite or even more aggressive steel wool to remove the black and make it shine.

Small nuts/bolts, etc, I soak over night in apple cider vinegar, then clean with a brass brush and shine with a Scotchbrite pad.

[steven c newman]

Just tried the Vinegar Soak, for about half a day. All I had to soak stuff in was a cut down 1 gallon milk jug, meant I had to "rotate" stuff now and then. The "before"
315500
Mainly those drill bits, also had a couple pliers, and a few files. If a part stuck above the surface, it got a WD40 bath. After awhile, poured the mess out onto some weeds I wanted to kill. Dusted things with some baking soda....MEH, just clumped up
Took the treasures down to the shop, and had a wire wheel in the drill press....
315508
Drills and files and a couple clamps after the wire wheel got rid of the black crud left behind, as for the pliers
315509
Not too bad. This was my first time with Vinegar Soak. Need a better tub to soak stuff in. had a tub from a hospital stay......the dog is using it as a water bowl.....drat.

Not really set up for the electro stuff. Can't really afford a gallon of evaporust. Vinegar around here is cheap. May try it again, next time I have a bunch of stuff to clean...

[Phil Mueller]

Steven, if you do want to try electrolysis someday, it really only requires a tub, a 6-12 volt battery charger, a box of Arm & Hammer washing soda and a piece of scrap metal. The "waste" solution can be reused, or even tossed in the lawn.
The down side is each piece you want to de-rust needs to be connected to the negative lead...so in your case with lots of small parts, the vinegar soak is really an easier way to go.
Where it made sense was an old Wilton vise I had. Threw the whole thing in the bath...took the rust out of most every nook and cranny and loosed up some pretty stubborn nuts and bolts.

[Stanley Covington]

Anyone used toilet bowl cleaner before? Chris Schwarz wrote a blurb in Popular Woodworking about using it for rust removal on hardware in Jan 2013. A chemist friend warned me that it is based on hydrochloric acid, a chemical that binds with iron and cannot be neutralised and will continue to cause rust unless the metal it infests is entirely removed. Is it true?

Stan

[Jonathan Martell]

I haven't tried the toilet bowl cleaner. Walmart sells citric acid powder in the canning section for those that are interested. I haven't tried electrolysis yet, but it seems like a good way to go for most larger items.

[Pat Barry]

I have had good success using a cleaner called Iron Out. Its a powder that you add to water. It did a nice job of removing rust staining from porcelain surfaces (sink, toilet) but it needs time to work so submerging the parts should be easy in a small bucket. I don't know what the ingredients are

[mike holden]

Last Year I ran some comparative tests for a SAPFM meeting. Compared electrolysis, citric acid, lemon-lime koolaid, molasses, and evaporust. Upshot was that all worked about the same as far as rust removal. Evaporust was the only one that did NOT etch the metal. YMMV
315538

The rusty auger bits were left overnight in solution. Would a longer bath work better? Would it etch deeper? I dont have an answer for those questions. After this short comparison, I use evaporust as it seems to be fool resistant.
Mike

[glenn bradley]

I realize this is not what the OP asked about but, if he just wants the job done, Evap-o-rust is quick and easy. If he wants to see how vinegar or citrus work, please ignore ;-)

[Dave Anderson NH]

Mike-
I appreciate the fact that you described evaporust as fool "resistant". I have seen clearly demonstrated innumerable times over the years in all kinds of venues that there is no such thing as "fool proof". The fools just keep getting more and more creative.

[Paul Phillis]

I've been exprimenting with both citric acid and electrolysis. Etching has been a concern with citric acid, especially with deeply pitted rust as it is slow to move.

Electrolysis is easy with just a mobile phone charger and a couple of large paper clamps. Use sodium bicarbonate as electrolyte as it is very safe.

Electrolysis has trouble with shifting deep pitted rust. But a short soak in citric acid bath afterwards will then get the rust out of the deeper pits.

[Ray Selinger]

Evaporust is not foolproof. I have a line on a plane when I didn't have deep :rolleyes:enough coverage.

[Allan Speers]

I've always wondered what the big deal is with citric acid. Is phosporic acid about the same thing? (White vinegar, too.) They all stop the rust and turn it black, no?

I like phosophoric (spray bottle, or naval jelly) for rusty iron tools like wrenches, holdfsts, and such, because it basically parkerizes them. If you wipe them down and leave them black, they never rust again.

For stuff that I you to want be purdy, you just can't beat electrolysis. - but it has another serious advantage: Electrolysis actually hardens the first very fine layer of rust, next to the good iron / steel. There's a name for this stuff but I forget what it is. Anyway, it can harden it enough that, for instance, you can save a screw or threaded opening that would have been lost with any acid treatment. That' why treasure hunters use it.

[Paul Phillis]

citric acid is different to phosphoric. Phosphoric forms an inert stable iron phosphate compound that sits on the surface of the steel. citric acid dissolves the rust completely leaving only clean steel.

Electrolysis has difficulty cleaning out small holes because electrons tend to go to peaks and avoids valleys. Imagine a cup, the rim would clean up nicely but the bottom remains dirty. It is a reaction between the hydrogen gas and rust that cleans the steel.

[Graham Haydon]

Vinegar has proven to be the the most convenient rust removal method for me. All I need is a plastic tub, some vinegar I can pick up with the weekly shop and a 24 hour soak time.

[Allan Speers]

I've been exprimenting with both citric acid and electrolysis. Etching has been a concern with citric acid, especially with deeply pitted rust as it is slow to move.

Electrolysis is easy with just a mobile phone charger and a couple of large paper clamps. Use sodium bicarbonate as electrolyte as it is very safe.

Electrolysis has trouble with shifting deep pitted rust. But a short soak in citric acid bath afterwards will then get the rust out of the deeper pits.


I have to comment, being a big proponent of electrolysis, on the very common mistake being made here. (VERY common, you are in good company. - So don't feel too bad, Paul!)

First you say "just a mobile phone charger and paper clamps" is good enough, and then you say that the process doesn't do well on deep pits.

OK ...

You see the same thing with guys that are convinced "you can just use an old car battery charger" and then they complain that electrolysis doesn't work as good as they expected.

well, DUH.
---------------------------------

The fact is, you need a VERY GOOD power supply. One that has a quality inverter, so 100% of the current is actually DC. I gurantee that a phone charger is putting out at least 20% ac, which welds the rust right back onto your piece.

You also need enough current, (not available from a trickle-charger) but not TOO MUCH current (such as you'll get form a boost-charger)
And you need current limiting, so you don't get any run-away current due to the low impedance of the mixture. (In other words, no battery chargers (unless modified) and by all means no simple phone charger. (You CAN use a computer power supply, as they are fully regulated, but you're stuck with whatever amperage they put out.)

You also need an absolute minimum of 12v if you want good contact with all of the cathode, but 20V is highly recommended when you have deep pitting, or several pieces bolted together, etc. - And the amperage should ideally be adjusted, based on the size of your piece.

And last, you need a LOT of anode material, with full "line of sight" to the pice being cleaned. "A couple of paper clips" is simply not going to cut it. An entire cage of rebar? Now we're talking. Even better: A bunch of graphite rods or flat graphite plates. Graphite is ideal as it doesn't corrode or get all gummy with deposits.

There are other mistakes commonly made as well, such as the wrong percentage of soda, or not cleaning the anodes, or not having the anodes evenly spaced (which makes the current too low in some spots.) - Or using public water that has traces of chlorine in it.
------------

Bottom line: Electroylsis is absolutely fantastic, IF you get it set up correctly. This requires time & money, but only once.

============

I should also mention that most paper clamps (that I've seen) are made out of stainless steel wire. Using stainless for your anodes is a great way to get cancer. Seriously. look it up.

[Allan Speers]

Last Year I ran some comparative tests for a SAPFM meeting. Compared electrolysis, citric acid, lemon-lime koolaid, molasses, and evaporust. Upshot was that all worked about the same as far as rust removal. Evaporust was the only one that did NOT etch the metal. YMMV


Mike, I don't doubt your results, but I don't understand them, either, since electrolysis (properly done) cannot possibly etch iron or steel. Can you elaborate?

1: What do you mean by "etch?"

2: Did you use a quality, well-regulated power supply? (If not, I'd bet the farm that you were sending a little AC through your tub, which would indeed cause trouble.) Ah, now I see the un-modified battery charger in your pic. There you go. You probably also had run-away current, which causes too violent a reaction. That does 2 things: It damages fine details on your piece (like threads) and it causes the anodes to corrode too fast and get covered in gunk, which then insulates them and lowers the current to below where it can do any good.

(Yes, I've done a lot of research on electrolysis, mostly because MY first attempt was less than satisfying as well.)

[Robert Lang]

Allan, Can you recommend a good, value minded electrical device for electrolysis? Never tried electrolysis but would like to do so using your setup. Thank You!

[Joe A Faulkner]

A low cost battery charger will do the trick.
https://www.youtube.com/watch?v=54ADeB6V1rQ

[Allan Speers]

A low cost battery charger will do the trick.
https://www.youtube.com/watch?v=54ADeB6V1rQ

No, it will not.

It will work, sort of. Then you'll end up posting on forums about how electrolysis doesn't really work as well as you expected.

Been there, done that. Never again. Trust me on this one.

[Allan Speers]

Allan, Can you recommend a good, value minded electrical device for electrolysis? Never tried electrolysis but would like to do so using your setup. Thank You!


I really don't know, Robert. I happen to have a nice lab-grade variable supply, so I use that. You can usually find these used on Ebay, in good condition, for around $100 or so. (Maybe a little more.) If you consider the cost of Evaporust, a good electrolysis set-up isn't actually that expensive. I only recently found out about using more than 12v, and now that I've tried it, I'm a believer, so that's even more reason to get a good power supply.

I've seen articles that show how to modify a battery charger to make it work, though I don't remember all the details. Basically, you add a lightbulb inline, to limit current, and then you add a 12v battery (in series?) so there can be no AC current passed. (I think.)
After all that, you still have only 12v, and non-variable current, which is far from ideal, so I don't see the point.

Also, FWIW, the "treasure hunter" guys claim that the absolute best results are obtained by constantly varying the current (within a safe range) I'm not sure exactly what that achieves.Maybe it turns even ore magnetite into useable, hard metal, I dunno. Power supplies are available that do this, but they cost more.
---------------------------------------------------------------

I'm about to start refurbing my huge collection of planes & tools, which have been sitting in an unheated garage for over 10 years. It's a huge undertaking and so I've been re-thinking my rust-attack scenario, hence reading this thread. I recently tried Evaporust, and the slightly less-expensive chelation concentrate from Espirit, but the cost is insane, and I really don't see any advantage except maybe for saws with valuable etching. (And chelation won't save badly rusted bolts and threads, as electrolysis can.)

I also looked at Oxyllic acid (widely used by motorcycle repair guys and BMX restorers) and Di-Ammonium Citrate, as mentioned earlier in this thread, but again the cost is just ridiculous. BTW- As best I can tell, Di-Ammonium Citrate is actually the active ingredient in EvapoRust and other chelation products.
---------------------------

I think that a number of the ideas in this thread have merit, depending upon the specific application. Nothing wrong with good old Naval Jelly (phosphoric acid) in most cases. BTW- If you douse your piece in baking soda & water, after the phosphoric acid, not only does this instantly neutralize the acid, but it causes a lot of the black gunk to sort of "explode" off, requiring a lot less scrubbing at the end.

[Trevor Goodwin]

I just cleaned up a rusty bailey #4 last night using an Australian product, RustBuster, main ingredient is Phosphoric Acid. I wiped a little bit on the sides and sole of the plane and scrubbed away with grey scotch brite type pad, the surface rust came off really easily. I was left with some grey pitting that doesn't bother me - even I could remove I'd still have the cavities. For the non-plated machine screws I've soaked them overnight in the RustBuster. It doesn't etch the steel but converts the rust to a "Phosphorous of Iron" which has a dark grey appearance that is very hard to remove, I don't care though it is protective and the screws aren't visible. Rust on the blade and chip breaker was much harder to remove. I oiled the components after the treatment but I'm not sure if I need to "neutralize" the metal?

I'm calling bullcrap on Allan Speers comments on using battery chargers. I'm an electronics technician and I can tell you that the little amount AC ripple that passes through a charger is of no concern, and putting a battery in series will not eliminate it. Phone chargers do not generally have "20% AC", especially modern ones that are based around the 5V USB standard. Unless you have 50 gallon tub for your electrolyte with the anode-cathode separated too far, 12V battery is sufficient. A car charger is naturally current limited but you might want to restrict the current further to reduce resistive and chemical heating effects; a car interior light-bulb could be used for your current limit so could a resistor. Note that some (expensive) car chargers have fancy battery monitoring electronics that prevent you from using them for this purpose. An old computer power supply would work fine and they usually have their 12V current rating on the label.

[Pat Barry]

I just cleaned up a rusty bailey #4 last night using an Australian product, RustBuster, main ingredient is Phosphoric Acid. I wiped a little bit on the sides and sole of the plane and scrubbed away with grey scotch brite type pad, the surface rust came off really easily. I was left with some grey pitting that doesn't bother me - even I could remove I'd still have the cavities. For the non-plated machine screws I've soaked them overnight in the RustBuster. It doesn't etch the steel but converts the rust to a "Phosphorous of Iron" which has a dark grey appearance that is very hard to remove, I don't care though it is protective and the screws aren't visible. Rust on the blade and chip breaker was much harder to remove. I oiled the components after the treatment but I'm not sure if I need to "neutralize" the metal?

I'm calling bullcrap on Allan Speers comments on using battery chargers. I'm an electronics technician and I can tell you that the little amount AC ripple that passes through a charger is of no concern, and putting a battery in series will not eliminate it. Phone chargers do not generally have "20% AC", especially modern ones that are based around the 5V USB standard. Unless you have 50 gallon tub for your electrolyte with the anode-cathode separated too far, 12V battery is sufficient. A car charger is naturally current limited but you might want to restrict the current further to reduce resistive and chemical heating effects; a car interior light-bulb could be used for your current limit so could a resistor. Note that some (expensive) car chargers have fancy battery monitoring electronics that prevent you from using them for this purpose. An old computer power supply would work fine and they usually have their 12V current rating on the label.
Basic agreement with your comments here. While its true that a simple battery charger may have an AC component people should be informed that this AC component is much less than the DC output of the charger. For example, lets say you have that 12V battery charger with a 20% ripple (AC component). That 20% is 2.4V AC compared to a 12V DC output. The AC component is not going to take the DC output negative and won't therefore cause a reverse current and plating back as Allen was indicating. In fact the little bit of AC would effectively result in a current fluctuation but always a positive current. Go ahead and use the battery charger - it will work fine.

[Allan Speers]

I'm calling bullcrap on Allan Speers comments on using battery chargers. I'm an electronics technician and I can tell you that the little amount AC ripple that passes through a charger is of no concern, and putting a battery in series will not eliminate it. Phone chargers do not generally have "20% AC", especially modern ones that are based around the 5V USB standard. Unless you have 50 gallon tub for your electrolyte with the anode-cathode separated too far, 12V battery is sufficient. A car charger is naturally current limited but you might want to restrict the current further to reduce resistive and chemical heating effects; a car interior light-bulb could be used for your current limit so could a resistor. Note that some (expensive) car chargers have fancy battery monitoring electronics that prevent you from using them for this purpose. An old computer power supply would work fine and they usually have their 12V current rating on the label.

You can call bullcrap all you want, but this information comes from the websites of top restorers & treasure hunters. One guy worked for the Smithsonian. (You should probably call him and let him know that he's doing it all wrong.) I did a ton of research after being unhappy with my original (battery charger) results.

There is simply no question that one often needs more than 12v for optimal results.
12v is NOT sufficient if you have marginal (rusty) connections between several pieces, or deep recesses. Do a little research into what serious restorers use and you'll understand. Plenty of tests have been done on this subject, and empirical evidence is what counts, not what you read in some textbook.
- Or just try it yourself, as I have, and you'll understand even better.

Also, again, getting the current within a fairly small window is important for critical work. (Unless you think that all of the world's expert restorers are wrong.) How exactly are you going to do that with a battery charger? I'll wait while you desperately try to come up with an answer. I've got all day...



As far as the 12v battery in series with a charger, I have no idea if that actually works, which is exactly what I wrote. (note my use also of a question mark.) Some websites claim that this helps, so I included it as a possibility.

And while you COULD use "just a resistor" instead of a light bulb, that would be foolish. The bulbs (as you should know) acts as a sort of capacitor, giving a fairly even output. One could probably use a smaller bulb, and then a resistor, to dial-in the desired current, but why go to all that trouble?

And last, yes an old computer supply woks fairly well, AS I WROTE, you just don't have any control over voltage or current.

[John Stankus]

You can call bullcrap all you want, but this information comes from the websites of top restorers & treasure hunters. I did a ton of research after being unhappy with my original (battery charger) results. I've also measured this stuff and seen it on a scope.

And 12v is NOT sufficient if you have marginal (rusty) connections between several pieces, or deep recesses. Do a little research into what serious restorers use and you'll understand. Plenty of tests have been done on this subject, and empirical evidence is what counts, not what you read in some textbook.
- Or just try it yourself, as I have, and you'll understand even better.

Also, again, getting the current within a fairly small window is important for critical work. (Unless you think that all of the world's expert restorers are wrong.) How exactly are you going to do that with a battery charger? I'll wait while you desperately try to come up with an answer. I've got all day...

As far as the 12v battery in series, I have no idea if that actually works, which is exactly what I wrote. Some websites claim that this helps.

And while you COULD use "just a resistor" instead of a light bulb, that would be foolish. The bulbs (as you should know) acts as a sort of capacitor, giving a fairly even output. One could probably use a smaller bulb, and then a resistor, to dial-in the desired current, but why go to all that trouble?

And last, yes an old computer supply woks fairly well, AS I WROTE, you just don't have any control over voltage or current.

When I get back from teaching my chemical thermodynamics class I will work out the cell potential for the reduction of rust. 12 V should definitely be sufficient to drive this reaction, but I'll do the Nernst equation calculation to tell you exactly what voltage is needed. From my days dealing with plating (reverse of what we are doing here), interrupted DC or AC superimposed on DC (provided you don't go to the regime where the reverse reaction is favorable) is used due to diffusion constraints at the surface. There is no magic, just a little bit of chemistry. The other issue to look is the resistive contact to the object and the counter electrode. You may be dropping a lot of your voltage at those contact points. There will be a balance of the reaction kinetics and the diffusion of the reactants.

John, (Physical Chemist by day)

[Allan Speers]

Basic agreement with your comments here. While its true that a simple battery charger may have an AC component people should be informed that this AC component is much less than the DC output of the charger. For example, lets say you have that 12V battery charger with a 20% ripple (AC component). That 20% is 2.4V AC compared to a 12V DC output. The AC component is not going to take the DC output negative and won't therefore cause a reverse current and plating back as Allen was indicating. In fact the little bit of AC would effectively result in a current fluctuation but always a positive current. Go ahead and use the battery charger - it will work fine.

This is interesting and beyond my knowledge base, but again I defer to the actual restoration experts who are adamant about this issue. (And no, sadly, I didn't save the urls, and have already spent too much time on this, so I'm not going to start searching again. I waded through far too much nonsense the first time around.)

I am going to completely guess here, but it sounds like you're saying that with ripple current, the ac wave happens concurrently with the DC wave, and thus the higher voltage of the DC component overrides any effect from the AC component. Is this in fact what you mean? (It doesn't make sense to me, but I'm not an EE.) The way it sounded, when I read about it online, is that the current momentarily reverses (AC) for a shot percentage of the time, so it is JUST ac for that time period. If so, then surely the experts are right that it can compromise the electrolysis process. I suppose they could all be wrong, sometime info like this gets passed along from one incorrect source. It seems to me that, since ripple current cause the sine wave to go slightly square, the latter must be true. Otherwise, wouldn't you just see a sign wave but at lower amplitude on the scope?

Do you still disagree? (And don't laugh, I really want to know.)

[Allan Speers]

AND REGARDLESS:

My first electrolysis system used an expensive battery charger and a bulb-based current limiter, (I don't recall the actual current range I was getting, but it was within he accepted "proper" range) and I was not happy with the results. My current system, using a Lambda supply & 15 - 20 vdc, but with the exact same tanks and anodes, works MUCH better on difficult pieces. (Such as planes with frogs stuck on via rusted bolts.) There's absolutely no comparison.

And you can't call bullshit on my personal experience, so please explain it to me.

[Pat Barry]

This is interesting and beyond my knowledge base, but again I defer to the actual restoration experts who are adamant about this issue. (And no, sadly, I didn't save the urls, and have already spent too much time on this, so I'm not going to start searching again. I waded through far too much nonsense the first time around.)

I am going to completely guess here, but it sounds lime you re saying the ac wave happens concurrently with the DC wave, and thus the higher voltage of the DC component overrides any effect from the AC component. Is this in fact what you mean? (It doesn't make sense to me, but I'm not an EE.) The way it sounded, when I read about it online, is that the current momentarily reverses (AC) for a shot percentage of the time, so it is JUST ac for that time period. If so, then surely the experts are right that it can compromise the electrolysis process. I suppose they could all be wrong, sometime info like this gets passed along from one incorrect source.

Do you still disagree? (I really want to know.)
First off, the DC voltage is not a wave. It is an electric potential of constant magnitude. Take the common 12V car battery. There is always 12V present across its terminals and the bias is always such that the positive terminal is 12V higher potential than the negative terminal which is commonly regarded as 0. The AC portion, in the case of a battery charger causes the stated 12V output of the charger to fluctuate between some lower value (10V for example) and an upper value (14V for example). Thus the average value will be 12V thus it is termed a 12V battery charger. Better chargers may have less ripple (AC component). None the less the voltage output from a charger should never go negative other wise you would have a very poor battery charger because in those times it was lower potential than the battery its charging there is potential for the battery to discharge.

[Pat Barry]

AND REGARDLESS:

My first electrolysis system used an expensive battery charger and a bulb-based current limiter, (I don't recall the actual current range I was getting, but it was within he accepted "proper" range) and I was not happy with the results. My current system, using a Lambda supply & 15 - 20 vdc, but with the exact same tanks and anodes, works MUCH better on difficult pieces. (Such as planes with frogs stuck on via rusted bolts.) There's absolutely no comparison.

And you can't call bullshit on my personal experience, so please explain it to me.

The power supply you have is very good I'm sure at regulating the DC output with very little ripple therefore it is very efficient at delivering the energy to the task. I don't know enough about the chemistry to be confident but do expect that the higher voltage ourput (15V vs 12V) is very helpful in making the process work. Afterall it is 25% more energy that can be delivered at 15V as compared to 12V. If you run at 20V then this is 66% more energy available. Note that DC voltage is called potential energy. So, if this is the equipment you are comparing there is no BS with what you are saying in that regard. Do you have a current limiting device on the lambda supply? If so, you should use it to regulate the energy delivered to the electrolysis cell. At least ramp it up slowly - that's easier on the equipment.

[Daniel Rode]

I prefer simple and inexpensive solutions. Most of the time, I choose the simpler of 2 options, but that's just me.

I use lemon juice from the grocery store mixed with water. I don't measure but it's about 2:1. It can be had dirt cheap and it's worked perfectly for me. Obviously, the active ingredient is citric acid. I use red and gray scratch pads to remove the black and check the progress. Then I rinse with water and immediately apply a coat of WD-40.

My needs are basic. I want to remove surface rust such that the tool can be put back in service. My tools are all users so I don't care about preserving etchings and such.

[John Stankus]

AND REGARDLESS:

My first electrolysis system used an expensive battery charger and a bulb-based current limiter, (I don't recall the actual current range I was getting, but it was within he accepted "proper" range) and I was not happy with the results. My current system, using a Lambda supply & 15 - 20 vdc, but with the exact same tanks and anodes, works MUCH better on difficult pieces. (Such as planes with frogs stuck on via rusted bolts.) There's absolutely no comparison.

And you can't call b****** on my personal experience, so please explain it to me.

Not calling your personal experience as wrong, but an understanding of the physical processes helps with explaining what is happening and how to optimize.

First, the expensive battery charger may have been part of the problem, a cheap one may have worked better. Why... because the expensive battery chargers monitor the state of charge (potential of the electrochemical cells that make up the battery) and adaptively adjust for state of charge and other conditions. You may not have been getting the potential you thought with the expensive charger. **edit** also some of the more expensive chargers have a desulfating sequence that may have caused problems. **end edit**

The reduction potential for iron (III) (the oxidation state of the iron in rust) is
Fe3+ + e- --> Fe2+ +0.771 V
and from iron(II) to iron is
Fe2+ + 2e- --> Fe(s) -0.44 V

So looking at this half of the redox reaction greater than about 1.2 Volts would be needed to drive the reduction half reactions. You do need to take into account the oxidation half reaction for the total voltage needed, but with a sacrificial iron counter electrode this should give the minimum. The actual voltage will change with concentration but not by 20 Volts. There are also voltage drops for the connections, and the solution conductance. Poor design of the electrolytic cell (i.e. cell geometry) can cause issues with voltage drop due to solution conductance. Poor cell geometry may be compensated for by high voltages.

Mass transport is another issue, especially with DC arrangements. There may be no driving force to clear out the product ions from the surface, which may prevent fresh reactants from getting to the surface. The reliance on diffusion limit the reaction rate. One strategy, used in the plating world is to reverse the current but keeping the potential below where the reverse reaction would occur. This gives an electrostatic force to sweep out the ions from the surface.

Geometry is an issue for derusting of complex shapes (i.e. plane bodies and other tools). The reactants have to transport to the reaction site, for the reaction to occur. Bath geometry can be crucial.


John

[Pat Barry]

The reduction potential for iron (III) (the oxidation state of the iron in rust) is
Fe3+ + e- --> Fe2+ +0.771 V
and from iron(II) to iron is
Fe2+ + 2e- --> Fe(s) -0.44 V

So looking at this half of the redox reaction greater than about 1.2 Volts would be needed to drive the reduction half reactions
SO John, what happens if more voltage than necessary is applied?

[Mike Holbrook]

I bought a bottle of Evapo-Rust about a year ago. I just took a very badly rusted adze head out of it. It was caked in rust yesterday, looks almost like a new tool today. It may cost a little more than a grocery store concoction but for all the tools I have used it on over the last year I don't plan on experiment with something else unless someone comes up with something that works much better for much less. You can add water to it if you don't have enough to cover some item. I have added water to mine several times, probably works slower but I usually leave things to soak for a day or two anyway. As someone else posted I have had no problem with tool surfaces becoming etched. If a tool is not covered in the liquid you may end up with a line where the surface was soaked for different times, but that should be expected.

[Mark AJ Allen]

I'm surprised no one has suggested Coca-cola. I used Coca Cola to turn a completely rusted file right down to bare metal shiny after a 2 hour soak and a little scrubbing with a brass brush. I only did it because I thought it was a wive's tale. No doubt you can try to electrocute yourself or inhale fumes from stronger rust-removal solutions if that's what you're into but the Coke gets it done cheap and fast and you can pour it down the drain when you're done.

[Jim Koepke]

I'm surprised no one has suggested Coca-cola.

Coca Cola has some amazing uses. There are many pages on the internet devoted to the many uses. Some suggest these uses are a good reason not to drink this amazing mixture.

I recently used Coca Cola to remove some burned on food from the bottom of an enameled sauce pan. It took more than one soak and a plastic razor blade from Lee Valley helped.

jtk

[Trevor Goodwin]

This is interesting and beyond my knowledge base, but again I defer to the actual restoration experts who are adamant about this issue. (And no, sadly, I didn't save the urls, and have already spent too much time on this, so I'm not going to start searching again. I waded through far too much nonsense the first time around.)

I am going to completely guess here, but it sounds like you're saying that with ripple current, the ac wave happens concurrently with the DC wave, and thus the higher voltage of the DC component overrides any effect from the AC component. Is this in fact what you mean? (It doesn't make sense to me, but I'm not an EE.) The way it sounded, when I read about it online, is that the current momentarily reverses (AC) for a shot percentage of the time, so it is JUST ac for that time period. If so, then surely the experts are right that it can compromise the electrolysis process. I suppose they could all be wrong, sometime info like this gets passed along from one incorrect source. It seems to me that, since ripple current cause the sine wave to go slightly square, the latter must be true. Otherwise, wouldn't you just see a sign wave but at lower amplitude on the scope?

Do you still disagree? (And don't laugh, I really want to know.)


Allan, if this is beyond you knowledge maybe you shouldn't be arguing your point? What are your restoration experts restoring? Electrolysis is a destructive process in my opinion; you are removing material that was once useful to the tool but is now detrimental. For planes that are users who cares? More material gets sanded away when you flatten the sole/sides anyway. There are rust conversion processes that might be safer on antique tools, and I'm aware some tools have higher value in as-is condition rust and all.

What is happening when you have a small AC signal superimposed on a DC voltage is that the average voltage is at the DC level and the current always flows in the one direction it is not reversing, but with a small fluctuation in the voltage, not the "wave shape" as you imply. On a scope you will see your sine wave but it won't be oscillating about ground, rather a DC level. The AC ripple is dependent on the power supply design, and a full/half-wave rectified unregulated supply will always have a little bit of ripple, but it could also be produced by the chemical reaction at small levels, the inductive (not capacitive) component that the light bulb provides may filter the ripple but is not required to do so. If a 12V battery or charger can provide sufficient current, dependent on the total resistance of the circuit, then there's no reason it can't work, and there is plenty of evidence on the web to prove that people do have success with it.


Regarding the coca cola, I think phosphoric acid is the active ingredient here. Maybe the sugar contributes too? http://blog.fooducate.com/2009/06/30/11-quick-facts-about-phosphoric-acid-yes-that-chemical-in-coca-cola/

I've also had success using RustBuster (phosphoric acid) on brass components to remove tarnish before buffing with brasso. I think it can ruin metal given enough time though because my steel wools pads turn into a black sludge if I leave them soaking in it.

[Paul Phillis]

In regards to Allan's post ridiculing my suggestion that a phone charger can be used for electrolysis.

I tried to keep things fairly simple as I was posting from a phone. So I apologize for over simplifying and not pointing out that a phone charger would not provide a strong enough voltage or current to really get into deep pits, or provide a truly professional finish. I thought that would be understood.

My point was that people interested in electrolysis can get started very cheaply with nothing more than a phone charger, which will do a fair job on a small object such as a chisel.

I'm sure there are better systems out there, and if I was doing a lot of rust removal I would probably invest in such equipment, but I think that stuff is all beyond what the original post was about.

Thanks for the input and comments which has sparked an interesting discussion, it's been a long time since I did this in chemistry.

Paul

[Bill White]

PHEWWWW! My head hurts. I think that I'll just drink a gallon of vinegar and citric acid mixed with Coca Cola, hook a battery charger to my toe, stick a chisel in my hand, and turn on the charger.
Will that derust my liver?
(Shhhhh. I'm just jerkin' you guys around.)
Bill

[Jim Koepke]

Will that derust my liver?
(Shhhhh. I'm just jerkin' you guys around.)

It just goes to show there are many ways people have found to end with similar results.

jtk