# Oxcilic Acid to Remove Rust



## firemedic (Dec 26, 2010)

It's been talked about here but I never tried it as I was happy with Evaporust.

I needed some Oxcilic Acid today for a furniture build so while I had a can I decided to try it as a rust remover. I noticed some peculiarities and I wanted to discuss them.

I have a couple of comments on this stuff.

First off - it works pretty well. In fact I was surprised at how well it worked. I dropped an old rusty Irwin auger for a hand brace in it and it did a nice job of removing the rust and pretty quick.

The odd things I noticed are these:
It smells like Evaporust.
It leaves the same patina as Evaporust.
It looks like Evaporust when lightly spent.
It even taste like Evaporust - just kidding!

So... We know Evaporust is pH neutral and we know Oxcilic Acid obviously have a pH of less than 7 but why so similar? Is Evaporust a buffered Oxcilic Acid solution??? Hmmmmm

Anyone with a stronger Chem background have any thoughts on this possibility? 

Just a freak coincidence? 

My wheels are turning!


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## Dave Paine (May 30, 2012)

firemedic said:


> The odd things I noticed are these:
> It smells like Evaporust.
> It leaves the same patina as Evaporust.
> It looks like Evaporust when lightly spent.
> It even taste like Evaporust - just kidding!


I am not going to get into the chemistry, but my own observations are:

The smell of Evaporust and Oxalic acid are not the same for my nose.

The patina is different. Evaporust is grey. Oxalic acid is a light green. Evaporust patina covers most of the metal. I have not been able to determine why some parts of the metal have the light green patina and some do not.

Evaporust generates black particles in the solution. Oxalic acid generates light green particles same colour as the patina. The Evaporust particles do not settle out. The oxalic acid particles do settle out.

I have not attempted to taste either product. :yes:

Another forum member EricD mentioned that oxalic acid works best when warmed to > 70 deg F. I agree warmer is faster than cold. For the winter months I would leave the solution in a southern facing window to have the sun warm the solution. Warmer does seem to work faster than < 60 deg F solution.

My oxalic acid was 1 tablespoon per gallon.

This was my thread after the first use.

http://www.woodworkingtalk.com/f11/first-time-using-oxalic-acid-rust-removal-48107/


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## firemedic (Dec 26, 2010)

Lol, I mixed my solution a bit stronger... :laughing: as in 6 oz (weight) in 1 Qt of warm water :yes:

The evaporust I have used has always had a greenish tinge to it. The piece I soaked in the Oxcilic Acid did have a grey patina. It may be different on cast iron.


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## Dave Paine (May 30, 2012)

I may try a stronger solution next time. I have a Stanley No. 6 and No. 8 planes on the way so more opportunities for rust removal. This time I may take pictures of the metal before and after the solution bath.


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## firemedic (Dec 26, 2010)

Dave Paine said:


> I may try a stronger solution next time. I have a Stanley No. 6 and No. 8 planes on the way so more opportunities for rust removal. This time I may take pictures of the metal before and after the solution bath.


Dave, I haven't had much time to revisit this so I have a question fer ya.

I have about 100 planes to clean up. Evaporust will cost me about $700 for a 55 gal drum shipped but is an option as it's what I generally use. 

Electrolysis is out because it will remove the japanning which is out of the question. So...

How does the acid do with the japanning?


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## Turner1944 (Jan 26, 2013)

*Rust Removal*

There are a number of people in the local woodworking club around the Ann Arbor, MI. area that have had excellent results with Citric Acid baths. I am thinking it was for other than heavy pitted rusty items. I have seen some of the results and I must say it will be my method of choice if/when I need to remove rust.

David Turner
Plymouth, MI.


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## Dave Paine (May 30, 2012)

firemedic said:


> Dave, I haven't had much time to revisit this so I have a question fer ya.
> 
> I have about 100 planes to clean up. Evaporust will cost me about $700 for a 55 gal drum shipped but is an option as it's what I generally use.
> 
> ...


My oxalic acid solution has no effect on the jappaning, so it is a safe and inexpensive method for your large batch of hand planes which need cleaning for the LSU. If I recall you mixed a stronger batch of oxalic acid, but I still do not expect it will affect the jappaning.

It does work faster when warm, so start with hot water and leave in a warm room or the sun if possible.


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## retfr8flyr (Aug 7, 2013)

Have you tried using vinegar? I have had great success just soaking tool in white vinegar for rust removal. It's amazing how it gets rid of the rust.


Earl


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## firemedic (Dec 26, 2010)

Dave Paine said:


> My oxalic acid solution has no effect on the jappaning, so it is a safe and inexpensive method for your large batch of hand planes which need cleaning for the LSU. If I recall you mixed a stronger batch of oxalic acid, but I still do not expect it will affect the jappaning.
> 
> It does work faster when warm, so start with hot water and leave in a warm room or the sun if possible.


Thanks, as much as I like evaporust I think I'm going to go with the Oxy.

And yes if I go that route I will be installing a heating element into 55 gal drum as well as an agitator. :thumbup:


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## firemedic (Dec 26, 2010)

Oh, and we will be doing some experimentation on this for bulk processing Fe artifacts from archaeological digs that have to be stabilized so this will be for more than just my planes.

I will have to do some research into the chemistry of this to be sure we don't have any ventilation issues to contend with.


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## Millzy (Nov 30, 2011)

Naval jelly and a green 3m pad cleans up rust


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## firemedic (Dec 26, 2010)

Millzy said:


> Naval jelly and a green 3m pad cleans up rust


Yes it does.

This is not an option for hundreds of tools and thousands of site dig artifacts though.


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## Gilgaron (Mar 16, 2012)

I googled the formula for the chemical reaction between rust and oxalic acid, and it looks like you get water, ferrioxalate and hydrogen. So you'd probably want some venting or other way to prevent hydrogen from building up.


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## firemedic (Dec 26, 2010)

Gilgaron said:


> I googled the formula for the chemical reaction between rust and oxalic acid, and it looks like you get water, ferrioxalate and hydrogen. So you'd probably want some venting or other way to prevent hydrogen from building up.


Thanks, Gil.

I spoke with a couple Chemist I know and each of them said "I don't know" lol. I was planning to do more research, and still will, but thank you for the info! It gives me a direction of thought.


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## Pirate (Jul 23, 2009)

Be aware that Oxalic acid can cause cancer. I believe it can absorb thru the skin.

A number of years ago, I found it dissolved iron rust stains like magic. As well as bleached wood good.
After paying $6 =/- per pound, for "wood bleach" I found a pool supply store, where I bought a 40 or 50 # bag for about $1/# Split it with some friends.


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## Dominick (May 2, 2011)

Pirate said:


> Be aware that Oxalic acid can cause cancer. I believe it can absorb thru the skin.
> 
> A number of years ago, I found it dissolved iron rust stains like magic. As well as bleached wood good.
> After paying $6 =/- per pound, for "wood bleach" I found a pool supply store, where I bought a 40 or 50 # bag for about $1/# Split it with some friends.


Everything causes cancer. 
Especially in California.


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