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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.

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.
 
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The photograph of the two angles says it all concerning the finish. I cannot help but notice what appears to be significant shrinkage of the treated angle; it's now about 1/3 smaller than the untreated angle.

sketchglass (author)  andrew.mead.12533 months ago

Citric acid doesn't shrink metal. That's silly.

The first image of the two squares is a photoshop, there is only one square. I put two pictures together, so any size difference you see is because of that. Nowhere near 1/3rd smaller though.

I forgot I wrote that. I kill me! (never mind). Good instructible but I admit having trouble and no luck finding citric acid in retail stores. I know of a pharmacy that compounds chemicals and medicines--surely they'd have citric acid as I have a use for some gentle rust removal in a safe compound like citric acid and water. Pax!

Try a health food or GNC store. Some Michaels and Hobby Lobby stores also carry it.
sketchglass (author)  andrew.mead.12532 months ago

The cheapest place I've found citric acid is the Indian grocery store, it's with the spices. A good grocery store should sell it as well.

ferjanyen1 year ago
There is a product call Ferricloride, you get it from any good boat chandlers. Takes rust marks from any thing inc. stainless steel. Good luck.

Ferric chloride will eat into the exposed surface of the metal one is trying to restore if you let it soak for very long (it's often used to etch copper PC boards, and probably cheaper at an electronics store than a boat supply store given their markets). I would use it with caution for restoring old steel items, and definitely not if there are etched designs to be preserved in the metal being restored. Also, it will stain fabrics, wood, etc. if it drips onto them by accident, and rubber gloves (and non-metallic containers!) should definitely be used if soaking/etching items in it. It is also not a good idea to pour it down drains!

If you neutralize it with baking soda it is actually safe to pour down the drain.

Ferric cloride is no joke. If you use it you have to agitate the bubbles it makes away from what you are working on or your results will be uneven. I work as a gun engraver and have used it a lot. Once accidently left small puddle of this stuff on a 16 gauge peace of sheet steel overnight in the morning it had eaten right through. It seems to work more agresively on metal that has not been work hardened.
bettina-sisr3 months ago

As a metal worker and environmentalist I try to use the least harmful stuff to complete a task, and I have found that to remove rust there are 2 more ideas that work wonders. First is Molasses! Yes Molasses. The ratio is 10 (water) to 1 (molasses) but I have found you can use a LOT more water. You just need a container big enough for your metal to be submerged, and time, it can take days, to weeks. There will be a molasses smell during, and funky foam will form (hmm?) in the shape of the metal on the surface (kinda cool actually) The second is Vinegar, and again the ratio is different for everyone, from 100% to 10:1, experiment for yourself to find what works. I think the vinegar is a lot like citric acid in why it works. GREAT INST!!

sketchglass (author)  bettina-sisr2 months ago

Hej bettina, thanks for sharing. never would have thought to try molasses!

sbrittain33 months ago
Catherine I will look for you a fb page post a pic of your car. Mine is Wimbledon white. I have posts on there you should be able to find me. Look forward to seeing your car. :)
sbrittain33 months ago
Bumpers? I have some light surface rust on my 65 Fairlane safe to use on them?
I just inherited my Grandpa's '65 Fairlane 500 Sport Coupe from my Dad. Where do you get parts? I'll need a few.
Hello Catherine welcome to the wonderful world of owning a Fairlane. Sports coupe awesome. The first thing I would do is join Fairlane Club of America. http://www.fairlaneclubofamerica.com/ If on Facebook join the Fairlane group. You will find a ton of info from booth. The Fairlane club site has parts for sale and there is a good chance you will find what you need cheap. I also go to rockauto.com for parts they even have some of the accessories for our year. If there is a way I can message you I will send my email so you can ask me for help anytime. One thing I love about the 65 is we are a rare car at car shows and cruisenights so we get alot of attention. :)
Wow, thank you so much. I'm going to join the fb group now and hit up the club after work. I'm so looking forward to driving this car again. It's what i drove in high school in the early 80s.

diet coke for bumpers or anything chrome for that matter.

Thank you Mr. January.....
VendicarD3 months ago

How can I conveniently remove flesh from bone without producing anything detectable by the neighbors?

Boil it for a long time in a large pot. I do 2 chickens in a large show cooker for 10 hours to make delicious chicken broth.

Buy a large fish tank, some hamster bedding, a colony of Dermestid beetles, and a bunch of air fresheners?

Done.
Namirreh3 months ago

Gpop

You could even use WD-40(a rust inhibitor) as a buffing agent.

rf Namirreh3 months ago

WD-40 eventually causes rust since it contains alcohol which attracts moisture.

lionsden rf3 months ago

Just looked at a can of WD40 I happen to have in the shop. There is no alcohol listed, plus it is described as "drives out moisture" hence the name "WD40" where "WD" stands for "water displacement". It is also called "flammable" because of the propellant used but once it is out of the can and on a surface I have NEVER seen it burn (in fact my son just tried to light a small puddle of the stuff to see what happens. - nothing.)

lionsden lionsden3 months ago

Further checking shows "petroleum distillates" which are flammable.

LDM1 rf3 months ago

WD-40 was designed to evaporate h2o, that's what the WD stands for, water displacement and it took 40 tries before it was perfected : hence WD-40, just a little history. Happy tinkering!

Namirreh rf3 months ago
That shouldn't be a problem, the stove would/should be washed off after, or it will smell,so what ever it's washed with(dish soap,citric acid etc.)would remove all residual film left.If it is stainless steel, it won't rust unless you remove the finish
shawnlambert3 months ago

Thanks for this Instrucable... I like a solution I pour down the drain without destroying the environment. Great post.

It is a nice instructable. Using citric acid has two effects, it has a low pH (high acidity) but also a complex forming activity with iron. So, don't use it for too long on your equipments, or they will disappear. It is present in high amounts in lemons, but it is rather cheap in some stores (drogist?).

PetraP13 months ago

Just brush it on.

PetraP13 months ago

Brush it on.

afarrakhov3 months ago

Vinegar can be used to remove a rust too.

ljhtg3 months ago

Fantastic, can't wait to try this out! Thanks for posting.

jeffcole3 months ago

What a good idea. An old timer once told me you could also use molasses to achieve rust removal, but it tends to smell a bit. This way seems easier.

Thanks for sharing.

Deltic3 months ago

You can't beat the old methods! For larger items that are too big to soak mix a paste using lemon juice (i.e. citric acid) & salt. Spread on surface, leave for a while then rub with a cloth & plenty of elbow grease. Rinse & repeat as necessary. Once cleaned up protect with oil or a couple of coats of clear auto lacquer.

M2aestro Deltic3 months ago

Careful with your mix of citric acid and salt, not from a personal safety aspect, but because residual salt on the parts accelerates rusting.

jspence13 months ago

Do you think this would remove bluing from a firearm?

M2aestro jspence13 months ago

I personally have cosmetically ruined chemically blued parts that were not protected with a lacquer or varnish by using rust removers. i had to then re-blue the parts. You would not worry about heat-blued parts, I think. I have heat-blue small parts (small tools, steel screws, and watch hands) by placing them on a bed of clean quartz sand in a wide jar lid that rested on a wire screen. The whole assembly of screen, lid, sand, and parts was then heated over a gas flame until the metal turned the desired blue color. After the parts were cool enough to handle, a fine film of tool oil was wiped onto the steel parts. I do not believe that this heat bluing is subject to change by citric acid, but am interested to hear if anybody can inform me from personal experience that I am wrong.

M2aestro3 months ago

Coke contains phosphoric acid, and I have absolutely no idea whether-or-not it contains citric acid. Phosphoric acid changes rust; I believe you get a black iron phosphate on parts so treated. I have removed rust from many items with Coke, both decaf Coke and regular Coke, which requires rinsing of the sugar from the parts. An advantage of Phosphoric acid (and of Coke) for eliminating red iron oxide, the rust to which we usually object, is the black iron phosphate product, which somewhat inhibits rust, just as black iron oxide somewhat inhibits rust, as long as we oil the parts after drying them. Whoever stated that coke does not remove rust must not have any experience with this. I believe oxalic acid is also effective for removing rust (and have used boiled oxalic acid in water solutions to remove rust in automobile blocks), but I do not suggest it as better because I believe it is much less safe than citric acid to handle oxalic acid. I think that I recall that it can eat holes in clothes, much the way hypochlorite bleach can. You may also be able to by a buffered phosphoric acid solution sold as a metal prep at some hardware stores in most states. I have used that acid, rather than citric acid, because I knew that it leaves a slightly protective coating on rusty parts. However, one should brush off scaley rust before treating parts this way if those parts are to be painted. The directions with most metal prep solutions suggest that you rinse off the de-rusted part, which may leave it very slightly yellowish. The part should be dried very quickly after rinsing to inhibit more rust formation. Perhaps Coke and Citric acid are the two safer solutions, as compared to Oxalic acid and to Phosphoric acid.

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