Rust removal using oxalic acid

Use oxalic acid to remove rust from steel parts (I would not recommend it for cast iron).
Only use on steel. Do not use with other metals.

Before use, where gloves and goggles and work in a well ventilated area. Do not get the acid on woodwork as it will stain (acts as a bleach on wood).

In the example below I have not even tried to brush off the surface rust before treatment.

The image below shows a sprocket wheel with a fair amount of rust.


Sprocket in a container of hot tap water with about a dessertspoon of oxalic acid powder.


Sprocket after two 1/4 hour treatments. Wash thoroughly in clean water and then dry.


Do not leave items to soak any longer than necessary. This is an acid after-all and is removing metal.

Regards,

David

Looks good but I think I will stick to wire brushes lol
Jonesey

Looks a good way to remove rust, where do you buy the acid from?

Stu.

A number of companies sell it. For small quantities (around 1kg) it is probably cheapest to buy it from Ebay.

Regards,

David

thanks for sharing it with us david
ive heard a lot about this sort of thing
regards,mike...

You can also use molasses and water (1:10). It takes a bit longer but the result is the same.
Greg

Thanks for the info Greg but I don't think you can get molasses in the country. Sure someone will tell me different

Stu.

stationary stu wrote:Thanks for the info Greg but I don't think you can get molasses in the country. Sure someone will tell me different

Stu.

I think you can as a fishing bait ingredient, try a local tackle shop, it's been a few years since I last went in one so I could be wrong.

Don't they use it in home brewing??? Or am I getting mixed up with something else???

oxalic acid is used by bee keepers, they use it to kill a bug in the winter. so it should be quite easy to find.
richard.

I thought it had something to do with Sugar but didn't know what so here's the answer and it does say in the text about rust removal.

http://en.wikipedia.org/wiki/Molasses

Stu.

A good remover of grime and the loose rust is good old brown sauce.
So the wife tells me.
Griz

Griz your wife is correct but I wouldn't like to buy enough to clean an engine, maybe have to raid Burger King and nick all there sachets

Stu.

You're bloody joking! I was working at a cafe (also living in) when it shut very quickly (the tennants did a moonlight-flit, leaving me homeless & jobless), I took loads of stuff with me when I left, including a load of sauce sachets!

I threw the lot away a few months back! It was real cheapo stuff as well, probably the best stuff to use.

Oh well, there's always Tesco Value.

Hello,David.
Some years ago,after consulting my old school chemistry books, I did some tests for rust removal, trying (separately) Oxalic Acid and Olec Acid. I can't remember how the Olec worked out, but when I looked where I had them stored, I found just the Oxalic, and so decided to give it a try just recently. I find that it removes the rust beautifully, but after washing, (and I have tried several things such as detergents and lubricants, and also repeating the process) I am finding that when the liquids dry off, the rust returns immediately! Then I have to sand it off. Admittedly, the new rust is only surface, and the acid DOES nicely remove any pitted rust, and the resultant surface rust is certainly preferable, can you offer any suggestions? Do you experience a similar problem yourself? Here in Queensland, Australia, things dry pretty quickly in the sun most times, and I certainly didn't expect this to happen. Years ago I didn't experience the same difficulty, as far as I remember, but at that time I was doing items made of better classes of steel. The problem is occurring with mild steel. I realise that your post is not recent, but since this is such an important subject and can potentially save a lot of members a lot of time, I am taking the chance. I find I can still buy the Oxalic readily only a couple of city blocks away and recently paid about $20 for a kilogram, which both pleased and surprised me at the time. The dealer had no knowledge of Olec Acid whatever.

The most recent item I tried to de-rust was partially painted, and while still wet, after the oxalic and the washing, had the appearance of being freshly painted-- the patches of old paint had apparently softened up and magically spread evenly over the entire surface. I was quite excited for a short while...until it dried.

Any suggestions welcome from anybody !!  

Thanks,
Bruce.
Rockhampton,
Australia. 

cool, but what i want now is something that removes the black tarnishing.
I want shinny steel!!

Callum  

callum12 wrote:cool, but what i want now is something that removes the black tarnishing.
I want shinny steel!!

Callum  

Thats easy................ a large dollop of elbow grease! - and perhaps wire wool

If you play it safe and have the engine running (no neck ties or baggy clothing) then the engine will do the work for you!

You can always attach an appropiate wool pad to a longish stick - so if needs be it can be sacrificed instead of you - and the RPM will save you a lot of trouble....

and then linsead oil works wonders in keeping it looking good - it takes a couple of weeks to truely dry though...

I am sure the team on line here will have other methods... probably a lot safer and easier but thats how i like doing it.....

best anyway!

Hamish

I bought this C12 & pump the other day, as can be seen the tank was pretty rusty. I happened to have some Oxalic Acid from some failed attempts to clean a resin sink, but I must say that as a rust remover it's done a nice job. All of that rust is now gone and I'm left with some of the original paint plus some grey steel. I left the tank covered with water in a bucket with about 6 desert spoons of OA. Best results were after about 2 or 3 nights, at the 3 night mark the steel stared to go grey and after 4 no more rust but a bit greyer. The inside is also in the same state. After drying for a while, the grey has turned light green which may be the original paint, so maybe a while longer would not hurt. In any case it's now ready for a bit of rubbing & priming or I may just spray a bit of lacquer on for now.

I haven't tried this yet, but I do now have a molasses dip tank for rust removal. It takes a week or 2 rather than days, but does get you back to nice clean metal.

I'm told the molasses reacts with the rust to make some kind of acid, maybe it's the same kind of stuff? I dunno, but what I like about molasses is you can leave the stuff in there for months, forget all about it, & it will come to no harm.

I also now have an ultrasonic cleaner, which can remove rust to a reasonable degree, in hard to reach places, with a strong citric acid solution up to about 40-50 degrees Celsius. But the solution doesn't last long & eye protection is a must! If that stuff gets in your eyes you don't notice until it's too late, then it feels like arc eye (welding flash burns). I lost a good nights sleep to that one.

BTW, anyone doing a molasses tank, it's roughly 9-10 parts water to one part molasses (get it from a horse feed place) & make sure the tank is covered! It ferments after time & absolutely stinks!

What are draw backs on using it on cast please David

See also thread on using citric acid.

https://ukengineforum.forumotion.com/t8394-rust-removal-using-citric-acid?highlight=citric+acid

I've dunked cast cylinder heads overnight and they came out a treat.

Hi can anyone tell me the best mixing Ratio Oxalic crystals to warm water for rust removal Please