Oxalic Acid- will it damage my paint?

[magilla0_2]

When I was an apprentice painter we used Oxalic acid to remove water stains from timber prior to varnishing.
I still remember the burning eyes, running nose and !! BAN ME NOW FOR SWEARING !! dry reaching cough that used to come from sanding the product off again.
Be careful eh ?

[Imwit]

Thanks for doing that Philip. The red guard looks great.
Next question.. Anyone prepared to test it on old style transfers?

[Clydesdale Scot]

When I was an apprentice painter we used Oxalic acid to remove water stains from timber prior to varnishing.
I still remember the burning eyes, running nose and superfantastic dry reaching cough that used to come from sanding the product off again.
Be careful eh ?

days before Safety Data Sheets?

I bought a tin in the 1990s to use to bleach timber after chemically stripping it, prior to staining and finishing. It is in a powdered form and concentrated.
I use the same precautions as I would with any chemicals (Roundup etc).

However in doing this demonstration last week, I had no skin contact with the acid, either in the concentrated dry form or after dilution in the water at ANY time.
It was only after each piece had been soaked and rinsed in fresh water were they handled.

[Clydesdale Scot]

I used the same procedure on some chrome rims for one of the staff at the LBS
the state of the rims
chromerimsbeforelarge_zps86055b63 by philip.knight, on Flickr

into the makeshift bath
rimssoaking_zps82aef33f by philip.knight, on Flickr

and after the soak (24 hours) and lightly rubbed with an old green kitchen scourer
Chromerimsafterlarge_zpsb1a0c4b2 by philip.knight, on Flickr
the fluid under the last image is the excess Penetrene I used inside the rim walls to disperse the water and deter rusting.

The bath was then used for a 24 hour soak of the two Bullock mudguards (one partially done in the test earlier in the thread). These have now been removed from the bath, rinsed and drying.

[tooslowtorace]

Where does one get oxalic acid?

[HappyHumber]

Where does one get oxalic acid?

Hardware stores. Sometimes primarily labelled "Wood bleach". Sold in the paint/surface prep section.

[Clydesdale Scot]

In Bunnings and Masters as "Diggers Rust and Stain Cleaner".
But the concentration they use is way in excess of that which I use!
They are looking for instant effects, with bike parts it is usual to go slowly.
by going slower, it is easier to deal, and you can check on the progress and decide when it is time for a bush down and another soak; or when it is done.
And it is good for steel, not aluminium.

[geoff_tewierik]

Worth using on this type of rusted eyelet situation? Or will it pooch the anodised rims?

[Clydesdale Scot]

the conventional wisdom is to keep oxalic acid away from aluminium and anodised finishes. eg this thread

[simon.young]

Thanks for posting this thread and keeping us upto date.... I'm getting ready to dunk a 70s kid dragster to do some testing....

But I was also wondering about rust converter http://www.supercheapauto.com.au/online ... 5818#Cross on paint chips that have rusted. eg on the seat stay in this pic. Will it damage the paint or discolour it?

I guess I really need to test . Maybe on that old dragster.... Has anyone tried something like this? any tips?

[commando]

Don't look for it in the paint section at Bunnings, the Diggers Rust and Stain Cleaner is in the building area with all the concrete and stone prep/cleaning supplies. The 2kg container for $27 should last you a looooooooong while.

[find_bruce]

The supercheap rust converter you linked to is phosphoric acid, just like most of the rust converters. Diggers Rust & Stain Cleaner is oxalic acid. I am not about to enter into the religious debates about the relative merits.

[Clydesdale Scot]

from what I have seen through searches, the action on rust is similar: oxalic acid/phosphoric acid/acetic acid

for those few spots on the frame, I would treat the spots rather than a full bath.

[Imwit]

Tried a little test.
Had some deck cleaner.
67 ml oxalic acid per 1L cleaner.
Used 250 ml to get 17 ml oxalic acid ( nearly Philip's 20 ml - 4 teaspoons).
Real rusty roadster seat stays in 5L water for 20 hours. (Bottom half immersed)
No real reaction seen.


Before

After


So at about $3 per 250 ml do I bother trying again with more cleaner or just get some crystals?

[Clydesdale Scot]

I suggest a longer soak, a lower concentration is a slower process
I have previously soaked some items for a week. Check once a day, brush off any of the yellow deposits.

[yugyug]

I'm a beginner with this kind if stuff, but I've been using the phosphoric rust converter to treat spot rust in paint chips, and I have not noticed any effect on the paint. I just dab it in lightly and let it set in, wipe off excess.

[simon.young]

Tried a little test.
Had some deck cleaner.
67 ml oxalic acid per 1L cleaner.
Used 250 ml to get 17 ml oxalic acid ( nearly Philip's 20 ml - 4 teaspoons).
Real rusty roadster seat stays in 5L water for 20 hours. (Bottom half immersed)
No real reaction seen.


Before

After


So at about $3 per 250 ml do I bother trying again with more cleaner or just get some crystals?

I got this at Mitre 10 store in Hobart $27 i think. Used 50g with 3.5 litres of water


In 24hrs it looked like this


Gave it a scrub:



Maybe I little heavy handed with the amount, but I need to find out reaction times. It was quick. But that was a free rusty 70s dragster from the curb.

Next I'll try the frame...

For parts that I care about, I will use a weaker concentration, and let it sit for a few days.

I assume the black marks are where the rust ate through the chrome plating?

[Imwit]

Trial no 2 was more successful.
Still using the deck cleaner but taking Philip's advise, used a greater concentration (approx 25 ml OA for 5 L water) and over 7 days. Only the bottom part immersed.
Before..


And after..


Wiped off every day before and after work.
Most of the cleaning seemed to be done after a few days but interestingly didn't see the yellow spots appearing until the last few days. They were still coming up but only in a couple of places.

So anyway, the deck cleaner works but is more expensive (and may take longer)

[Clydesdale Scot]

That is an impressive result. There is a surprising amount of paint left hidden behind the rust.

The process gives the best results and no mechanical damage to the surface.
I cringe when I see ebay sellers say the rust can be easily removed with steel wool. It might, but you risk taking the surface coating with the action.

[LG]

Maybe I little heavy handed with the amount, but I need to find out reaction times. It was quick. But that was a free rusty 70s dragster from the curb.

Next I'll try the frame...

For parts that I care about, I will use a weaker concentration, and let it sit for a few days.

I assume the black marks are where the rust ate through the chrome plating?

The black marks are generally where the chrome was so badly corroded small patches have either flaked off or the rust just bubbled up through the chrome leaving a small gap. Sadly following a rust treatment these patches of bare metal will corrode again unless treated. I've found sometimes these patches of steel turn black, other times they seem to simply look like steel.

My trick for small patches on an otherwise clean frame is to soak a piece of rag in the oxalic mix then place it against the frame and hold in place with glad wrap.

[gazo]

I have been using Citric Acid with great success - it's cheap, you can buy 75g in the baking section at Woolies; mix 25g with a few inches of water in the bottom of a bucket, leave your bits to soak overnight, and voila. Just wipe off and rinse with water.

Best of all, it's non-toxic. You can put your hands in it, don't need to worry about splashes or rubber gloves or kids and animals. I don't know why anyone would touch Oxalic Acid.

[Clydesdale Scot]

.. leave your bits to soak overnight, and voila.
Best of all, it's non-toxic. You can put your hands in it, don't need to worry about splashes or rubber gloves or kids and animals. I don't know why anyone would touch Oxalic Acid.

I wouldn't be leaving my bits in it.

And if you follow this safety advice you should also wear protective gloves, protective clothing, and keep kids and animals well away.
Just like I do with Oxalic acid. And I don't touch oxalic acid. I use appropriate equipment.

[gazo]

And if you follow this safety advice you should also wear protective gloves, protective clothing, and keep kids and animals well away.
Just like I do with Oxalic acid. And I don't touch oxalic acid. I use appropriate equipment.

Um, that safety advice is for Oxalic acid.

Another good thing about Citric Acid - you can sprinkle it on your fish or chicken roast.

[Clydesdale Scot]

as you like having things served up on a plate Citric Acid
but given your concerns about oxalic acid, you had better keep spinach, cabbage, broccoli, brussel sprouts, parsley off the plate

The reason I started the thread was to document the use of weak oxalic acid to remove rust and establish if there is any detrimental impact on old paint.

There is ample material on the internet as to other forms of rust removal. Oxalic acid is commonly used and so the quantities to be used are well documented.

I have had a large container of oxalic acid in powdered form for over 20 years, and it will last me my lifetime (and no, I don't plan on consuming any to hasten my early demise). Ingredients used in food preparation are kept in the kitchen; cleaners and oils etc for working with and the cleaning of bikes are kept in the garage. I am just old fashioned there. My ultrasonic cleaner, vacuum pump, dremel and air compressor are also not used for food preparation either but for bikes.
The only blurred line is found with my dirty fingerprints on the bottle of liquid detergent kept in the kitchen. This is irrefutable evidence that I use it to clean my hands after working on my bikes. And to ally any concerns, I do not use the dishwasher detergent, nor do I consume the dishwasher detergent, or sprinkle it anywhere but into the dishwasher dispenser. I use my ultrasonic cleaner for cleaning bike parts, I do not use the dishwasher.
My wax chain lube is used for lubing chains. I am very unadventurous.
I have once used a BBQ to dry a leather saddle. That use is a matter of public record.

My apparent intolerance with people wasting my time is not listed as an acute hazard/symptom of exposure to oxalic acid.

[munga]

spactose intolerant.