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Best Rust treatment?


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Hi All,

 

I have just been let down by Moss as they are out of stock on their Rust Convertor fluid (both parts) and Rust Encapsulator paint. They tell me I will be lucky to get any before Christmas as they are on back order from the States.

 

Can any of you recommend an easy to source, UK product? We need to get on preparing the engine bay, ready for paint prior to dropping the lump back in. There is some surface rust to treat and a small amount of rot in the battery tray we need to stop spreading. Any advice gratefully received.

 

Thanks, Ian

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Thanks Guys!

 

I will look into all of the above, much appreciated.

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I've used Jenolite and Bondaprimer for many years after trying most of the products during the '70s.

Jenolite disappeared for a while due to legal difficulties but I managed to get a new stock from Wilco earlier this year. I probably should try to replenish my Bondaprimer if it's still available (although I hope I don't need to get involved with too much of this sort of thing in future). The nice thing about this product is (or was, the last time I used it) that you can slap on one or two coats fairly liberally with a brush and leave it for a long time (years, if necessary) before rubbing down and top-coating.

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Jenolite? Rustbuster? Esatwood's Rust Dissolver @ £10/litre?

 

Pshaw!

They are all phosphoric acid based, and so is farmer's "Milkstone Remover"

At £10 for 5 litres at any farmers supplies centre, this beats anything sold to unsuspecting car restorers.

The only disadvantage is that it isn't a jelly, so it doesn't stay on vertical surfaces well.

Otherwise use it just that same, paint on, scrub/wirebrush, repeat until it dries to the black finish of iron phosphate, which is a good surface for priming.

John

Edited by john.r.davies
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Dear Ian,

 

Many of these 'branded' rust treatments have phosphoric acid as the main ingredient. This can be purchased from chemical suppliers such as Lennox Chemicals here in Dublin. We have always used this as a rust treatment with great success. Currently we are renovating a TR3A 1959. Phosphoric acid comes in a plastic container with a screw top. One litre would last you a very long time. All you have to do is paint on the phosphoric acid over the rusty area and leave for 20 minutes. Than agitate the rust with a stiff paint brush or someting stronger if you prefer. Keep painting on the acid and agitating. After a few applications you will see the rust dissolve and see bright meatal appearing. You should keep doing this until all the microscopic black marks have disappeared. If necessary and depending on the amount of rust present, you can reapply over a couple of days although this is rarely necessary. When you have completed the treatment wipe off the excess (it doesn't evapourate easily) using rough tissue paper. There is no need to wash it off with water which to my mind seems to defeat the purpose. Make sure you paint the treated areas with an appropriate anti-rust paint immediately after treatment.

 

A 2 or 3 litre bottle can be purchased for around €40 as far as I can remember (I think that included delivery, it is very heavy - much heavier than water) that amount will last you forever and you can give presents of small amounts to you friends.

 

Phosphoric acid gives much better results than any of the expensive branded items. Make sure you wear plastic gloves and goggles!

 

Regards,

 

MGT (TR Man)

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Hi Ian,

all the previous posts give good info.

Basically there are a few approaches to attacking the metal maggot.

 

The most effective is to cut out the rusty metal and insert new - not always possible or convenient but you end up with a good surface for paint etc.

or

Attack it with acid type stuff.

This has two courses of action. Phosphoric acid ('Metal ready' is one product) this leaves a clean metallic surface after pickling.

Tannic acid (Kurust etc) this leaves a blackish surface -the rust is converted into inert rust due to the tannic acid action.

The post phosphoric surface can be painted with etch primer (phosphoric based) then either treated surface can be coated with a quality sealer primer (corroless,

Rust encapsulator Por15 etc) then undercoat, top coat. Some of the paint sealers don't take to well to other paints being applied on top.

To get the best out of the acids you need to remove (mechanically) as much surface rust as you can.

or

Then there is grit blasting. If you just want a small area cleaned then you can use a grit gun with focused nozzles that work quite well. etch prime and paint.

or

If it is really awkward or you haven't got the time then remove as much rust as possible then paint with (corroless, Rust encapsulator Por15 etc) top coat and waxoyl.

 

Dinotrol has always had a good name but there are a number of excellent industrial products (Astrolan, Socopac etc) that are outstand in keeping rust at bay.

 

Roger

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Glad for your support, MGT, but:

 

A/ The Lennox Chemicals product is lab.reagent, high purity and 80-88% concentration, so that will make 6 litres of 40%, same as the Milkstone stuff, but for £33, or £11/litre. Compare with £10 for 5 litres, £2/litre. You choose!

 

B/ Iron Phosphate is relatively insoluble in water, so that it converts the rust into that black coating. That is the point of using it. Thick rust can be scrubbed to remove the phosphate, but a thin layer may be good, as when dry, the coating is hard and makes a good base for paint. If you want to get back to bright metal, you would be better off with another acid - dilute hydrochloric would be fine.

 

John

 

PS Roger,

See this site - website for professional corrosion businesses, Corrosion Doctors.

Read their comment that, "The most frequently used formulations are based on phosphoric acid which cause the rust to be converted to firmly adhering iron phosphate layers."

Then compare Kurust at £5 for 100mls, with phosphoric at £10/5 litres. You choose. J.

Edited by john.r.davies
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That's interesting, John. I had not realised that we have been using a stronger concentration of phosphoric acid and that probably explains why you can actually see it working when using the laboratory stuff of 80-88% concentration. This would also explain why it is so heavy.

You are right to compare the price differential and obviously cost is important. However one cannot increase concentration easily but it is easy to dillute the stronger stuff if desired.

It is a pleasure to use the stronger stuff as it works so easily. It is not as easy to get hold of though.

 

You seem to know a lot about the details. Are you a chemist?

 

Regards,

 

MGT

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You seem to know a lot about the details. Are you a chemist?

Regards,

MGT

 

No, I'm a physician and an anaesthetist, so I've learnt a lot more basic science, across a wider range than most doctors. Electrochemistry is part of respiratory physiology (acid-base balance).

 

But the stuff about how conc. is that acid was just internet datamining - Lennox Chemicals is on the net, lists their two types of H3PO4, with a datalist: http://www.lennox.ie/pp/Chemicals_A_to_Z/C...acid_04107.html

 

John

Edited by john.r.davies
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No, I'm a physician and an anaesthetist, so I've learnt a lot more basic science, across a wider range than most doctors. Electrochemistry is part of respiratory physiology (acid-base balance).

 

But the stuff about how conc. is that acid was just internet datamining - Lennox Chemicals is on the net, lists their two types of H3PO4, with a datalist: http://www.lennox.ie/pp/Chemicals_A_to_Z/C...acid_04107.html

 

John

 

Ah, we are colleagues. I'm an ophthalmologist and that is why I am careful about recommending goggles for any of these jobs. You'd be surprised the number of people who do not wear eye protection. Last week I removed a large corneal foreign body from a patient who was cutting out rust from an old Rover. He had worn his goggles for most of the job and then subsequently noticed a final piece of rust remaining, did one quick final grind without his goggles and hey presto, got injured. I saw him a few days later and having first removed the metal he was left with a 'rust ring' which took a bit more work. You will be glad to hear that I did not have to resort to phosphoric acid. :lol:

 

Regards,

 

MGT

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  • 4 weeks later...
Ah, we are colleagues. I'm an ophthalmologist and that is why I am careful about recommending goggles for any of these jobs. You'd be surprised the number of people who do not wear eye protection. Last week I removed a large corneal foreign body from a patient who was cutting out rust from an old Rover. He had worn his goggles for most of the job and then subsequently noticed a final piece of rust remaining, did one quick final grind without his goggles and hey presto, got injured. I saw him a few days later and having first removed the metal he was left with a 'rust ring' which took a bit more work. You will be glad to hear that I did not have to resort to phosphoric acid. :lol:

 

Regards,

 

MGT

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