Citric Acid

[Michael O'Sullivan]

I have some small tools that I would like to try and de-rustify. I have a bag of citric acid powder as well.

What is the recommended addition rate of the CA powder to water?

[Mike Brady]

1 cup to a gallon of water. Remember that hand scrubbing with a small wire brush is essential in good rust removal. The citric needs to get into the rust in order to effectively remove it. Brushing makes that possible. Also remember to wipe everything down with oil or WD-40 after the derusting. You might get flash rusting if you don't.

[Jim Koepke]

Remember to wear eye protection if you are brushing this with the citric acid.

I usually let mine soak over night before involving the brush. I like minimal work for maximum output.

jim

[Dan Andrews]

I haven't been using citric acid for de-rusting for long, but I have a lot of it recently. I have discovered a few things that have made a big difference in ease, speed and results when using citric acid.

1. If the item has been oiled, or is greasy, wash the item in a solvent that aggressively cuts grease. I prefer laquer thinner, but have also used mineral spirits.

2. The hotter the solution the faster it works. I put the solution in a tin can, put the item in the can, put the can on the coal stove and cover with aluminum foil- be sure to tuck the aluminum foil inside the can so condensation drips back into the can not on the stove. Let it cook for about 1/2 to 1 hour.

3. Wash the item in warm water and begin scrubbing with a wire brush, stiff nylon brush, or scotch-brite type pad, whichever seems most appropriate for the item.

4. Expect to repeat the dip and scrub several times. Repeat dips don't seem to take nearly as long to be affective as does the first.

5. Polish the item with 600 then 1000 grit wet or dry abrasive paper. Follow up with finer paper, or a polishing compound if a high shine is desired. I have been doing this wet sanding with water keeping the item totaly wet as I work so rust won't start. I am going to try sanding in kerosene so rust starting while sanding or immediately after won't be an issue.

6. Wax or oil immediately after completing the de-rusting and finnishing process.

Good luck and have fun.:)

[Nick Laeder]

What is the advantage of citric acid over Naval Jelly? I just bought some Naval Jelly last night because I couldn't find citric acid. Does the Jelly do the job?

[Josh Bowman]

I've done a few items and it works very well by taking a plastic bucket. Put some water in it, put a couple of spoons of baking soda in it. Get a piece of rebar or other steel. Hook a battery chargers positive to the rebar and the negitive to the part to be cleaned. I've let some very rusty items fizz and bubble for a day or two and they come out smooth and black. The black simple washing off with a little soap and warm water.

[Harlan Barnhart]

What is the advantage of citric acid over Naval Jelly? I just bought some Naval Jelly last night because I couldn't find citric acid. Does the Jelly do the job?
Citric acid is non-toxic. You don't need to wear gloves or use in a ventilated space. And it seems to work just as well.

[James Scheffler]

What is the advantage of citric acid over Naval Jelly? I just bought some Naval Jelly last night because I couldn't find citric acid. Does the Jelly do the job?

I have used Naval Jelly and it does work. There are a couple of disadvantages. First is the safety aspect, because it is pretty caustic. Second, it's difficult to really immerse the object and just let it sit. You can leave Naval Jelly on a rusty surface for a while because it's pretty thick. However, it does sort of dry out so that you have to remove it and put down fresh material pretty often.

I haven't used citric acid, so I can't comment on that. However, I prefer Evaporust over Naval Jelly, and it sounds like citric acid shares some of the advantages of Evaporust.

Jim

[jerry nazard]

+1 on Evaporust. Good stuff.

[Jim Koepke]

My number one reason for using citric acid is not only that it works, it is cheap.

I think I bought a pound of powder for a couple bucks and there is still some around in a bag in the shop and a gallon bottle mixed up in an old jug.

jim

[Jonathan McCullough]

I've tried electrolysis and Naval Jelly, both of which work. As I understand it, the Naval Jelly is really phosphoric acid, and the reason it comes in a gel form is so that you can slap it up on boat hulls above you and it won't drip down on your head. Otherwise, phosphoric acid is used in a strictly liquid form, like HCl and H2SO4, and is used not only for de-rusting but also putting a pre-emptive, "black rust" type of oxidation on steel, like blueing.

Does anyone know of a source for phosphoric acid in a convenient form like the brewer's citric acid powder? I've been cleaning off a lot of old saws lately, and where the etching is gone for good, it would be good to be able to dip the spring steel in a bucket of phosphoric acid to blue it up a bit and give it some rust preventative properties.

[Jim Koepke]

Does anyone know of a source for phosphoric acid in a convenient form like the brewer's citric acid powder? I've been cleaning off a lot of old saws lately, and where the etching is gone for good, it would be good to be able to dip the spring steel in a bucket of phosphoric acid to blue it up a bit and give it some rust preventative properties.


I think Bob Smalser mentions a product that can be purchased. Not sure if it was from a ship chandler or a gun dealer. I know some hardware stores carry a lot of these kinds of products the big boxes don't.

Check this thread:

http://www.sawmillcreek.org/showthread.php?t=66090

jim

[Jonathan McCullough]

Yeah, that Oxpho blue is pretty expensive though, with all sorts of "ultradangerous shipping surcharges," and I know phosphoric acid is dead cheap. They put it in colas to give them a "tangy" taste because it's actually cheaper than citric acid, apparently. So where can I get some, I wonder? Should I just dip my saws in The Real Thing? Just joking. It's got to be in something innocuous like cat litter or Granny's Blueing Wash or something. You know what I mean.

[Jonathan McCullough]

Well there it is at Home Depot for $12 a quart, cleverly concealed as "Phosphoric Acid Cleaner." I'll give this stuff a try and report back. It's for cleaning/etching rocks and stuff apparently, and you can dilute it.

[Michael O'Sullivan]

Thanks for the responses -- the tools at issue are nothing special, but I figured I would try out derustification on something cheap, before I try restoring something nicer.

[george wilson]

I believe Naval Jelly years ago had its potency reduced by the do-gooders,and isn't what it used to be.

[David Keller NC]

Yeah, that Oxpho blue is pretty expensive though, with all sorts of "ultradangerous shipping surcharges," and I know phosphoric acid is dead cheap. They put it in colas to give them a "tangy" taste because it's actually cheaper than citric acid, apparently. So where can I get some, I wonder? Should I just dip my saws in The Real Thing? Just joking. It's got to be in something innocuous like cat litter or Granny's Blueing Wash or something. You know what I mean.

Actually, you can indeed use "the real thing", or any other carbonated soft drink as a de-ruster. The phosphoric and carbonic acids in the soda will convert the rust to ferric oxide, which is soluble. The problem with using Coke or some other soft drink is that it's not very concentrated, so you may have to use an excessive amount of it if you've a fair amount of rust to remove.

One warning to those reading this thread - if you have a saw with an etch, like a Disston or a Simmonds, citric, phosphoric, and many other common acids will obliterate the etch. A combination of scraping and light sanding is much preferred for this particular tool.

[Peter Evans]

Phosphoric acid comes in a few different forms, probably the easiest to get is panel beaters wash. After stripping the metal, the PA wash leaves a protective coat that means the metal does not need to be immediately primed. I do not want this coating on my tools.

For most items, rust flashing can be prevented by immediately drying the tool with a heat gun or hairdryer to drive all moisture out of the metal, and then while tool is still hot, oiling it with a thin oil (3-in-1) and keep on heating the item to drive the oil into all the pits. When sunny I leave the items out in the sun for a few hours.

For sharpening files and rasps, in my temperate coastal climate I find that properly dried items do not rust if wrapped in newspaper for protection after they are heat dried.