Rust removal using citric acid

Having read the posts on oxalic acid I thought I'd throw this in.
Citric acid also works very well. Obtainable as crystals from home brewing shops or more economically online from ee-by-gumbay.
Get the cheapest - you don't need food grade. If you can use hot water even better - but don't breath the fumes.
Also great for descaling kettles - so you can book to the household cleaning budget rather than engine restoration!

Whow that is an impressive result from such a basic cheap product - I will certainly give that a go.Thanks for mentioning it.
Kev.

You're welcome Kev.  I used a mixture of about six or seven tablespoons of citric acid crystals in one and a half litres of water. Pickled for 24 hours then 5 minutes with a wire brush.
BTW I have just thought about making the solution as usual then adding wallpaper paste to make a gel that you could brush on. Will give it ago on post results.

Hello Paul,

Many thanks for sharing this and what impressive results - the gel idea is a cracker!

I'm on the case myself for a number of smaller components!

best

Hamish

Hi Hamish,
If you only have small items then use a plastic pot and hot water.
Really thick rust might require a second pickling after first wire brushing.

I used a cup full of citric acid crystals in a litre yoghurt pot (Milbona Greek style from Lidl - very nice !)
Stirred well then added about half a cup of Wilkos finest wall paper paste.
Follow the instructions on the packet but go for a pretty thick mix. It adheres quite well to vertical surfaces so good for large items.
Results below - not to bad after overnight soak and a five minute scrub but will apply second coat and post result tomorrow.

Before


Gel applied


After one application

Very nice results - and you beat me to it !

What I like about citric acid is its not as corrosive as other methods - really useful thread!

best

Hamish

And a lot cheaper than Hammerite gel  - £13.72 per litre !

Final result after second application:

That works an absolute treat! - now I need to somehow ask the wife if i can lie an engine block in the bath

I take it you were using a stiff brush and water to remove the gel?

best

Hamish

Dead right. Wire brush and rinse off with water. Reckon it's ready for primer now.

Been working on the Villiers MK25 and, as seems usual, the air filter mesh was a mass of rust. So we thought why not try the magic potion?
First soaked in paraffin for a few hours to loosen up any remaining oil, then heated it up with hot air paint stripper to burn off residue - a tad smokey, should have done it out in the fresh air.
Then dropped it in citric acid solution overnight and look at the result. Apologies for not taking a before pic, you'll just have to trust me

Citric Acid works well to remove rust inside fuel tanks too even better if you can keep it fairly hot for a hour or two