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Oxalic Acid

Posted by Kimberly  
Kimberly September 30, 2004 02:32AM
Is Oxalic Acid sold under a brand name? I went to Home Depot to get some and they had no idea what I was talking about!!

Does anyone know where else I could try finding it...other than online??

Thank for your help!!

Kimberly (^o^)
David Von Bargen September 30, 2004 02:36PM
It is an ingredient in some wood bleaches (DAP). You might have better luck looking for it at a drug store.
Chris van Laer September 30, 2004 03:48PM
Oxalic acid can be purchased from a local drugstore, but it's purity is usually "reagent grade" or pharmecuetical grade, making it very costly. I use oxalic acid not only for mineral cleaning, for which it has no equal, but also in the gold refining process, as it precipitates pure gold from solution. I use a great deal of this in my shop, and we buy it bulk by the kilo (12 kilos at a time), and because it's "technical grade", it's not too expensive. As a result, we sell one-pound containers of "excess" stock to local mineral collectors for the purpose of cleaning minerals. Because of the commercial nature of this, I believe it's inappropriate for me to offer my product through this website, but you can contact me at my return e-mail address if you need any further help.
Franklin Roberts January 04, 2005 09:26PM
Oxalic acid is also the main ingredient in several brands of OTC car radiator flush. Run on in to your local auto parts store and start reading the fine print on the labels. The only other ingredients mixed with most of these products are usually surfactants (wetting agents). If anything, the presence of these will improve the performance of the OA in your specimens by allowing the solution to permeate into the tiniest cracks and voids to do its thing.

Franklin Roberts
Austin, Texas
H Sunderland January 08, 2005 12:11PM
I have a small bottle of Oxalic Acid Crystals. As I remember from chemistry days, if I dissolve the crystals in distilled water - warmed, I will get a supersaturated solution.
I have a specimen of Barytes which is partly coated with - I think- Limonite.
I don't think it is ordinary Iron Oxide (i.e. Rust).
In any case regarding rust, you can buy rust remover from car accessory shops.
It goes under the name of 'Jenolite'. Though I think the industrial concentrate is more potent than that sold in shops. Jenolite contains Phosphoric Acid (as in washing powders I believe) among other things.
Isn't there Oxalic Acid in Rhubarb?

Anyway, how do I get rid of the Limonite on my Barytes?
Should I immerse the specimen in hot concentrated Oxalic Acid?
These Iron compounds tend to be quite complex.
I have managed to physically chip away some of it.

H Sun.
Alfredo January 08, 2005 02:33PM
You don't need hot concentrated oxalic acid; dilute acid at room temperature will do fine... IF your "limonite" is really that (Fe''' oxyhydroxides). If the brown crust is something else, the oxalic acid won't work.

H Sunderland January 10, 2005 01:07PM
Thanks Alfredo, it remains to try it. Its a bit of blue Barytes I have, so its worth 'having a go'.

H Sun.
Dal April 25, 2006 11:37PM
Hi everyone,

Just to let you all know that you can get jenolite again, just go to there website or if in the UK go to

It is excellent rust remover, contains phosphoric acid so nutralises the rust better than any product I have ever used. Makes similar brands like hammerite and fertan products look like water!!

Jenolite also told me that they are planning to have the liquid form back in stock by summer so its back to business for all us that want a reliable well respected rust remover! I am over the moon that it is finally available again.

Good luck to you all.
Jeremy Zolan April 26, 2006 01:13AM
There's a product that I use to remove iron staining that works real well, it's called Iron Out and it's available in large quantities of the powder at hardware stores (it's about $5.00 US) and it'ssafer than oxalic acid too, you don't need to take any special preccautions except working in a ventilated area (Gives off fumes of SO2). It's active ingredients are Na(HSO4) and Na(HSO3).
Jesse Fisher April 26, 2006 07:10PM
Oxalic acid can usually be found in Home Depot-type stores (here in the US) sold as "wood bleach". I have seen other chemicals sold as wood bleach as well, so read the description of the product to make sure of what you are getting.

The active ingredient in "Iron Out" is sodium dithionite (also called sodium hydrosulfite). This chemical is not acidic, and is a better choice for removing iron stain from delecate minerals than oxalic. It is also less toxic. See the thread on cleaning fluorite for a more complete discussion.
Deb S May 24, 2006 08:33PM
"ZUD" a cleanser available at a lot of grocery stores, will take away iron stains.
DebS August 03, 2006 03:56PM
To the best of my knowledge, "ZUD" cleanser is oxalic acid based. It's next to the Comet and AJAX cleaners in a lot of the larger grocery stores. Try reading the label first, memory doesn't serve very well anymore.
Zbynek Burival August 13, 2006 09:25AM
And what about to contact large chemical shops and just buy online anything that u want?


If its not marked as a poison or very dangerous chemical theres no problem:) Im not sure about USA but in Europe I can buy most of chemicals when Im over 18 years including strong mineral acids etc.
Barry Flannery August 13, 2006 10:45AM
I haven't read the thread so I will just highlight the OA dangers, the big one is mainly to do with blood and attacks the iron in blood and reduces it's ability to clot (stop bleeding) so prolonged exposure will presumably make you susceptible to bleeding to death...!
Just treat it with respect and you will be fine.

Thomas Henderson September 12, 2006 11:05PM
I bought my oxalic acid from a professional painters' supply store. A 20kg sack of it was about $1/lb, as I recall. But I go thru alot of it in my cleaning.
Donovan Wood November 01, 2006 10:15AM
i live in south africa and none of the drugstores could help me so i got a hold of one of our local chemical suppliers through the phone book and they were able to supply me in bulk at a good price
Christine Johnson November 01, 2006 12:13PM
I live in New Zealand and obtain my supply of Oxalic Acid from chemical companies who supply chemicals to clothing dry cleaners etc. They use it to take rust stains out of clothes, materials etc. Not sure about USA, but this is far cheaper than buying it as wood bleach or for cars and it is available in bulk via this way. Might be worthwhile having a chat to a laundry or dry cleaning store owner.
Mark Rheinberger December 02, 2006 09:44AM

Here in Australia, well in the state of New South Wales at least you can buy Oxalic Acid from Some Paint stores or Hardware stores. Not all keep it but ask and I'm sure they will get it for you. Don't buy it in liquid form, buy it in granuler form it goes much further.

One product name is "Diggers" and there is another maker but I can't recall their name. The last Oxalic acid I bought was a 1kg bottle and cost about A$26.00.

Jon Ertman December 02, 2006 03:07PM
I use muratic acid and mix with distille water,and works faster,Jon.
eric December 02, 2006 05:49PM
H Sunderland Wrote:
> Isn't there Oxalic Acid in Rhubarb?
> H Sun.

not sure. i do know there is oxalic acid in Lamb's Quarter, a common garden weed. it is also quite nice in a salad. eat some dairy to counter the effects of the OA. perhaps you could make a tincture of lambs quarter to concentrate the OA in it.

Mark Rheinberger December 03, 2006 12:25PM
That's why you don't eat Rhubarb leaves and oxalic acid can be extracted from these leaves. But I don't know how.

Lloyd Llewellyn December 06, 2006 08:33AM

Your muriatic acid may work faster than oxalic at removing carbonates, but will hardly touch any iron-staining, unless, of course, the iron staining is itself attached to a reactive carbonate.
Jesse Fisher December 12, 2006 03:22AM
Actually, muriatic (hydrochloric) acid is quite good at removing iron oxides and hydroxides. It has a couple of drawbacks, however. Unlike oxalic, it is a volatile acid and will fume quite readily, particularly if heated. This does wonders to anything metallic in the vicinity. It, like oxalic, will require a good bit of post treatment leaching in distilled water to remove the iron-containing solution from any cracks or crevices in the treated specimen, otherwise one will end up with nasty yellow stains when the piece drys. HCL is also a strong (and agressive) acid, and will leach a lot more than just iron stain from many minerals. Given the readily available alternatives, I rarely use HCL.

Andrew G. Christy December 27, 2006 03:38AM
Some safety notes and botanical notes:


1. oxalic acid complexes iron, which is why it is a much better remover of iron stains than you would expect from the strength of the acid alone (although it is still a strong acid compared to most other organics). The ability to make iron unavailable to your body would indeed damge your blood if ingested, but the acidity is a bigger worry. I'm not sure about Barry's inhibition of clotting, though.

2. it readily reacts with calcium and magnesium, in 'hard' water, in minerals, and in body tissues, to form sharp, insoluble crystals of oxalate salts. Plants such as rhubarb and grape vines use this to store those cations in their leaves. When crystallisation of small oxalate needles happens in people naturally due to metabolic malfunction, it is called GOUT, and is extremely painful. If oxalate gets into your skin, you can give yourself artificial gout. Not a good thing.

3. never ignite oxalate or strongly dehydrate it, since it will give off deadly carbon monoxide gas when it decomposes.

Eric's "lamb's quarters" is Chenopodium album, common worlwide in temperate climates and known in the British Isles as "Fat Hen". Although a weed, it is also rather nutritious, and is a close relative of quinoa, spinach, beet, sorrel and rhubarb. Sour taste in these species is indeed due to oxalic acid. In rhubarb, this is at a tasty but non-toxic concentration in the stalks, but too high for safety in the leaves. Nevertheless, it is not strong enough to make a very useful limonite-dissolving natural extract, as far as I know. The pure, commercial compound is much more concentrated and absolutely not for consumption!

NB: because of the iron-complexing ability of oxalate, spinach is not actually that good a source of dietary iron!

Happy New Year, Everyone!
Eric Tripp January 10, 2007 10:23PM
You can usually get small quantities of Oxalic acid or proprietory agents containing mostly oxalic acid at any boat chandlers. It is used to remove rust stains from GRP (Glass fibre) boats.
Albert Mura January 11, 2007 12:27AM
Oxalic acid can also be found in a number of toilet bowl cleaners to remove the rust stains. These also can additional acid which helps the stain removal. The oxalic acid in Rhubarb has been attributed to deaths during the middle ages. I've used it often in the lab but please be careful, gloves etc.
Amitav February 21, 2007 11:49AM
Oxalic acid is also used as grinding agent in polishing of steel items in a vibro polishing machine aklongwith ceramic stones, water and other chemicals.

Is Oxalic acid acts as an grinding agent?

What is the better alternative to the oxalic acid in this case which is both less harmful and less costly.

Alan Plante February 21, 2007 03:58PM
If it is mixed with water then it is not a "grinding agent." It is a dissolving agent. Perhaps it is added to weaken the structure chemically so that the actual grinding agents in the mix can grind the material away faster? Or perhaps added just to clean the surfaces up as they are ground? I don't know; but I do know that oxalic acid crystals dissolve in water, making the water into an acid solution. There is no way that the acid can *grind* anything.


Amitav February 23, 2007 08:03AM
Thanks Allan. You are right. Oxalic acid weaken the structure chemically so that the actual grinding agents in the mix can grind the material away faster.

Can u please state an alternative to Oxalic acid which is less harmful, easy to handle, comparatively cheaper and at the same time the performance is equally good.


Alan Plante February 23, 2007 04:49PM
No, I can't. - I doubt that there is anything cheaper that will work as well for the particular application you are discussing. I think that less expensive acids (eg. vinegar, etc.) will not be aggressive enough to do what the oxalic does. I think the protocol that is being used is probably the best one that can be devised.


Peter Haas February 23, 2007 05:27PM
Citric acid is very similar in its properties, being a medium strong acid, a mild reducing agent and a complexant (chelant). Complexing is stronger with citric acid, but also more selective than with oxalic acid.
Amitav March 01, 2007 06:47AM
Allan we actually use oxalic acid in vibro polishing of steel materials which are then Ni-Cr plated. The reason of using the Oxalic acid is as stated by you.

If you are aware of vibro-polishing, I'll request you to help me in searching suitable chemicals which reduces the vibro polishing time substantially. As of now the time taken is at the tune of 12 to 14 hrs for fully polished (mirror) finish.


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