NB Recommendations for a "direct-to-rust" primer

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Avocet

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I need to paint some old iron railings. There's no (realistic) possibility of removing all the rust because they're so deeply pitted. The best I can do is "flake off the big lumps". Also, they're in a National Park so I have to keep the same final colour, which means that whatever I use has to be over-coatable with conventional exterior gloss. To date, I've used this stuff:

http://aquasteel.co.uk/

followed by red oxide primer, white undercoat and green gloss. However, it only "sort-of-works". I was just wondering what else might be worth trying?
 
I'm using Zinga from MG Duff - who you'll know as the manufacturer of all things anodic for boats. Rebuilding an old Land Rover and doing everything steel/cast iron with it. Overcoat with anything after 24 hours.

Red oxide primer is a just red paint - there is nothing special about it and it hasn't had anything vaguely anti-corrosive in it for years.
 
Avocet said:
I need to paint some old iron railings. There's no (realistic) possibility of removing all the rust because they're so deeply pitted. The best I can do is "flake off the big lumps". Also, they're in a National Park so I have to keep the same final colour, which means that whatever I use has to be over-coatable with conventional exterior gloss. To date, I've used this stuff:

http://aquasteel.co.uk/

followed by red oxide primer, white undercoat and green gloss. However, it only "sort-of-works". I was just wondering what else might be worth trying?
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The problem with anything that is painted over rust is that all of rust must be converted into an inert form. This is what rust converter tries to do.

The major issue is that unless all and I mean all the rust is converted the rust will come back.

I have a steel boat and have tried most available and some has worked and some not and it was due to the fact that when it worked the rust converter did convert all the rust. When not the rust returned irrespective of the type of rust converter that was used.

These days I use hydrochloric acid to clean all the rust away then phosphoric acid to remove the flash rusting you will get after the hydrochloric acid is cleaned off. I then use and epoxy paint to protect the surface with lots of coats of epoxy paint. Below the waterline I use epoxy tar as it is less hygroscopic that most other paints.

In your case I would grit blast the steel and then paint with epoxy primer.
 
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The problem with epoxy is it doesn't like uv very much.

Frost automotive sell a fabulous product called POR15 from the US but it's very expensive and also doesn't like uv, so would have to be overcoated.
Worth having a general look on the Frost website though, they sell all sorts of metal prep products as well as anti corrosion paints etc, although generally aimed at the automotive market.

http://www.frost.co.uk/

No connection etc just had good results from their products over the years.
Some are available cheaper elsewhere, others not available anywhere else!
 
I have a 2 pack primer called Jotamastic 87 which the makers claim is suitable for painting coastal structures in aggressive environments, I used it on our steel cradle which was rust free after 9 years exposure. It was not too expensive but very effective though it does not contain a convertor. I have unusual confidence in Jotuns claims for their products, Vinylester 88, their equivalent of Primocon is also great stuff and easier to apply than the two pack which drags a bit. It is a lot cheaper than yacht paints but you need to buy it in 5l tins.
Mail order from SML and another distributor on the South Coast.

Jotun regard Jotamastic 87 as their most suitable primer for use 'where proper surface preparation is not possible'
 
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Thanks all. No question of using acids, I'm afraid. Many of the railings go into flower beds! I like the look of that Jotun stuff though!
 
Might be worth trying POR (Paint Over Rust) which you can get from Frost, the classic car restoration supplies people. From memory you have to remove the big lumps of rust, but not the surface stuff. They say.
 
JumbleDuck said:
Might be worth trying POR (Paint Over Rust) which you can get from Frost, the classic car restoration supplies people. From memory you have to remove the big lumps of rust, but not the surface stuff. They say.
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Tried that onboard, wasn't too bad where the preparation was very good but on less well prepared surfaces it didn't do what it said on the tin. Flaked off after a few seasons.
 
I painted my railings with Hammerite smooth 25 years ago. Bomb proof. I suspect that the recipe has since been changed.
 
Interesting that Aquasteel don't make their MSDS easily available. You have to call and ask for it rather than being on the website. I suspect the product is acid based despite some of the evasive comments in their data sheet. Might be worth checking if surrounding environment is going to be sensitive.
A permanent solution will be all but impossible in your situation but I would suggest at least 2 coats of the rust converter and, when dry, brush off any powdery residue. Biggest issue will be getting an adequate thickness of a decent primer on. As already said, red oxide primer is just red paint these days. Virtually no protective qualities at all. Jotamastic 87 is very good but will be expensive. Plenty of other surface tolerant epoxies out there nowadays and many better for brush application. You will need at least 2 coats by brush and 3 or 4 would be much better. I think I would go with a conventional metal primer rather than epoxy over such a poorly prepared surface. Hammerrite has changed formulation fundamentally at least twice in the last 20 years but still probably one of the better products for this type of job. I don't really understand the point of white undercoat unless it helps the end colour be correct. Undercoat won't add any protection and an extra primer would be better. Covering white with green must be quite difficult to achieve. Gloss coat is meant to add just that. Gloss, and provide UV protection. Opacity is usually not that good.
 
I just did my keels with Vactan, I chipped pretty much all the rust off, then cleaned as best I could and stuck a couple of coats on. It is supposed to convert rust to a hard blackish grey surface which can be overcoated. The results were indeed quite impressive, the stuff was cheap and very easy to use aside from grovelling between the bilge keels. I then used 3 coats of epoxy and 2 of antifoul, but I can't say how well it will last yet. TBH I don't care - it looks a great improvement. http://performance-chemicals.net/vactan/
 
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