Instructables
Picture of Removing Rust with Citric Acid
This is one of the easiest, safest, and least abrasive ways to remove surface rust from old steel tools.

Supplies:
  • Citric Acid Powder  (available at drug stores or grocery stores as a health food supplement or a baking ingredient)
  • Warm Water
  • Container
  • Scouring Pad / Brass Brush
  • Rusty Parts
Safety:
  • Rubber gloves are a good idea
  • Don't splash it in your eyes
Precautions:
  • Do a test before trying this on something important - I've noticed it caused a swan chisel to turn very slightly yellow.
  • Do not try this on something like a saw blade with an etching you want to preserve - it might disappear.
Other Ways to Remove Rust:
Wire Wheel on a Grinder - this is probably the quickest way to remove rust, but it's still abrasive, so be careful around logos you want to keep.
Electrolysis - works well, but you have to be careful with batteries and water. not for the novice.
Sandblasting - very quick, but can leave a rough finish depending on the media. requires masking on painted parts.
Sanding - tedious and dirty and removes metal, but it works. sanding in very tight places can be impossible.

Advantages to using Citric Acid:
  • Does not remove painted finishes.
  • Less messy.
  • Requires nothing you don't already have in the kitchen.
  • Can be poured down the sink (citric acid is the main ingredient of some biodegradable cleaners).
  • Way cheaper than sandpaper.
 
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Step 1: Clean the parts

Picture of Clean the parts
removing_rust_citric_acid_02.jpg
The rust on this wood plane wasn't too bad. The chip breaker was the worst part, but it was mostly just thick surface rust.
  • The first step is to clean off any dirt with water and a sponge.

Step 2: Prepare the solution

Picture of Prepare the solution
  • Find a container that is large enough for the parts to lay down flat. This way you only need to cover them with a shallow pool of water.
  • Place the parts in the container and cover them with warm water.
  • Add the citric acid powder and stir it in. Experiment with the proportions here. I used probably a 1/2 ounce of citric acid with 15 ounces of water.
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Ninzerbean1 month ago

My citric acid is in powder form, therefor do you mean 1/2 ounce by weight or volume (like a tablespoon), with 15 ounces of water by weight or volume?

sketchglass (author)  Ninzerbean1 month ago
I used about 15 fluid ounces of water and maybe 1-3 tablespoons of powder. It doesn't matter how much citric acid powder you add, just experiment. If nothing seems to be happening, add more. There's no harm in using a lot, just keep an eye on your parts. Post back with your results!
Thank you for getting back to me so quickly. Unbeknownst to me I had copper and brass stuff in my pile of rusty and corroded scraps from using my metal detector. I used 1 rounded tablespoon of citric acid powder to 16 ounces of hot water. It was fun to see the huge difference and I only wish I had taken a 'before' picture to go with the 'after' picture. So, just so anyone knows, copper and brass and non ferrous metals are not so good to clean this way. My stuff is kinda pitted and rough but it's ok, I should have examined it more closely. Thank you again for sharing. I have used the electrolysis method with great success but it's a hassle to set up. This is so easy.
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NitroRustlerDriver made it!3 months ago

Used this on a small metal lathe I am currently restoring. Worked great!

Chuck Complete.jpgCompound Rest.jpgCross Slide.jpgLathe Before3.jpgUn-Rusted Coumpound Rest.jpgUn-Rusted Parts2.jpg
sketchglass (author)  NitroRustlerDriver1 month ago

Nice before and after pictures! that's a neat little lathe, how's the restoration coming?

Currently stalled. Cold weather has set in and I am unable to paint in the garage, which is the next step. First chance I get to start working on this again, I will.
Fikjast Scott4 months ago

Thank you for posting this, I can really use this process. I have tried other things, but I like your success.

The Rambler4 months ago

I bought a machete at an auction that has engraving on the blade but is also pretty rusty. Do you know of any solutions for removing the rust without damaging the etching?

sketchglass (author)  The Rambler4 months ago

You might try electrolysis:

http://www.instructables.com/id/Electrolytic-Rust-Removal-aka-Magic/

Coke works to.

To what?

No, Coke does not work.
I certainly does, the cheaper the better! Use it all the time, it also works for freeing stuck threads on bolts.
I agree, coke of any sort (cheaper the better though) does work. It's the phosphoric acid in it that is the key ingredient here. Commercial rust removing preparations like POR 15 products use phosphoric acid. Personally, I think electrolysis is the most effective method but, as the author has stated, it is a little bit nasty. Citric acid is a good 'green' method of rust removal so, thank you for this 'ible' :)
rimar2000 Kevanf111 months ago
Maybe YOUR Coke has more phosphoric acid than OUR. I tried it some years ago, even boiling in it the nails, but the result was too poor to say "it works".

I will try citric acid, if I can get it.
I have taken a can of coke and poured in the spark plug holes siezed 50s and sixies V8s and let it wait a day or two an pull started them with another car and roled the engine right over! Coke works well on steel and iron but not so much on aluminum.
If you can find mexican made coke made with real sugar cain it works so much better than the US made with corn surip, I don't know why.
doa1018 months ago

For rusted tools, socket sets I keep some used automotive anti freeze handy. Just place the rusty parts in a pan cover with the anti freeze and sit back drink a beer, Pepsi whatever if the part has only surface rust it will be clean by the time you finish your drink. But if it is heavily rusted just let it sit overnight.. Wipe it down real good spray it with furniture polish, car wax in a pinch spray some Pam on it. You can use the anti freeze over and over.

curbowman8 months ago

Could it work with lemon juice? That's very acidic. I have access to lots of lemons around here.

sketchglass (author)  curbowman8 months ago

I'm sure that will work! Post back with your results.

rkrishnan711 months ago
Nice instructions. I believe Vinegar and Coke also work quite well.

Vinegar (acetic acid) + Coke (diluted citric acid (from the lemon or lime flavoring) and some diluted phosphoric acid).

hbg1968 rkrishnan710 months ago

I have used vinegar in conjunction with Bicarb soda on tent pegs.

MrBillG59 hbg19689 months ago

Did it work? Vinegar is an acid and bicarb of soda is a base. Mixed together all you should have had left was salt water.

MrBillG599 months ago

Have you compared your citric acid method to Naval Jelly (oxalic acid) or EvapoRust (acidless)?

lsmith87130911 months ago
Any suggestions on how to clean a bike chain and untangle it easily

Ultrasonic cleaner with either Spic-n-Span or Simple Green will get it clean, then soak it in WD-40.

mg55412 made it!9 months ago

Skeptical at first, but my experience proves to me it works very well. I used the citric acid from3 packs of kool aid lemonade. I now have no rusty tools!

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thuber610 months ago
I came across this, and will admit that I had extreme doubts that this would work all that well. I am here to say that I am no longer going to purchase commercial cleaners EVER for the purpose of cleaning my tools. I placed some planes and various other antique tools in this stuff and I was thoroughly impressed as to how well it worked. many of the parts now look brand new and will be happy to show the results. I didn't have to have this in a ventilated room like with clr or works, and didn't feel I needed to put on a tyvek suit in order to scrub the parts. it didn't leave a black residue as bad as the commercial stuff. I want to thank you for this post. Oh and my wife didn't mind me using this at the sink to rinse as it wasn't harsh on the counter tops like the other stuff.
Might have to try this on a few things.

Another way to remove LOTS of rust:

http://myweb.tiscali.co.uk/andyspatch/rust.htm
That is a very interesting and extremely useful website you have written, well done and thank you from another UK rust remover ;)

IT's not my website, merely one I stubbled across t some point. I have used that method though and it works very well.

No matter, it's still a good resource that you have shared with the Instructables community and I, for one, thank you for it and for your own 'ible' :)

Hoopajoo11 months ago
Easy source for Citric Acid: Lemon KoolAid (or any other brand) powder mix. Usually, it's the first listed ingredient.
skexie Hoopajoo11 months ago
I just checked my Country Time Lemonade container, not that I didn't believe you, and you're 100% right! I can try this with the items I already have around the house now! Thanks!
jarikcbol skexie11 months ago
Its best to use the little packets of KoolAid. The tubs have sugar, which will make a sticky mess, the packets are just citric acid and flavor, with no sugar mixed in.
THAT,S really cool! I didn't konw that. Thank you!
ac-dc Hoopajoo11 months ago
You will get a lower amount of citric acid per dollar from KoolAid than just buying some citric acid.
ScubaSteve5111 months ago
Oil is not always the best choice...for metal surfaces that slide against each other, it is great. Otherwise, for rulers, etc. carnuba wax (or equivalent product) is best. Doesn't collect junk and won't stain wood, etc.
I found that Turtle Wax (for buffing cars) works really well for rust prevention on things like you describe.
tlebsack11 months ago
Great idea. Citric Acid (of less than 100% purity but still suitable for such projects) can be purchased in most American grocery stores under the brand name TANG.
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