Keel Painting ?

[Peegee]

I'm showing off cos its only December and the boat is scraped,stripped of a/foul, and ready for tarting up. My question is....the keels have cleaned up well and I have some "Fertan" to convert any residual rust. What would be the best paint to prime them with befor a/fouling again. Apologies if this is the Nth time the questions been asked.
Peegee

 

[Ubergeekian]

I'm showing off cos its only December and the boat is scraped,stripped of a/foul, and ready for tarting up. My question is....the keels have cleaned up well and I have some "Fertan" to convert any residual rust.

I tried various anti-rust formulations on th elarge mild steel plate which backs the keel on my Jouster. Absolutely the worst was fertan: rust was bubbling through as bad as ever in a week or two. In th eend I used Finnegan's No 1, which is a xylene-based, hammerite-like anti-rust primer. Still there, no repainting necessary 20 years later.

Just saying ...

 

[Peegee]

Thanks Orbister, just the sort of info/experience I'm looking for.
Peegee

 

[VicS]

I suggest you read the advice on paint manufacturers websites eg International Yachtpaints

If you opt for a common material such as Hammerite primer be sure you have already treated with arust converter such as Fertan in the same way that Orbister did

 

[Quandary]

Painting

To add a horses mouth account to good advice above -
You refer to keels but it is not clear whether they are iron or steel. If steel it may be possible to remove all rust and you can also try a rust convertor. If iron you may not get rid of all of it but you can still protect it. I could not do it up here at this time of year because my boat is outdoors and temperatures are too low or humidity is too high here for paint to adhere effectively to cold metal.
On steel and indoors, or somewhere warm and dry after abrading, use the convertor then coat with Primocon or similar, apply at least two more coats. (I would apply five to bare metal.) Rust convertor is a waste of time on its own, it must be overcoated with a good primer.There is a school of thought which regards convertors as ineffective and recommends mechanical removal then a primer. The brown or biege Hammerite primer is a compromise in that it is a combination of convertor with primer but I would still overcoat with Primocon. If iron, indoors and warm and really clean, use epoxy after thorough cleaning, build up rapidly to three or more coats then a coat of primocon as soon as the last coat goes off. If not warm enough for epoxy use the Primocon as above but if the metal stays below about 10 degrees you will have condensation under the paint so it is better to wait til spring even if this means rubbing down again. The exception might be in a dry east breeze.
Like most yacht paints Primocon used to perform better in the old days when it contained a lot of bitumen though that did bleed through white antifouling.
I used to be able to buy a fantastically durable and cheap brown metal primer used for machinery in a local pork curing factory so there are industrial priming paints made specifically for maintaining metal in salty environments but I can't remember the name (if it had one)
If you put enough good quality primer on it will last 5 or more years, except perhaps at joints and edges which you may need to touch up regularly with Primocon +antifouling.

 

[Ubergeekian]

If you opt for a common material such as Hammerite primer be sure you have already treated with arust converter such as Fertan in the same way that Orbister did

Interesting point, but after the fertan treatment I had to use a high speed wire brush - on an angle grinder - to remove loads of rust and get back to bare metal. It wasn't just polished rust (or converted rust) either, so I doubt if any fertan (or iron tannate) was left.

Finnegans No 1 is an anti-rust treatment as well as a primer. I haven't seen it on the shelves lately, but a google suggests it's still available.

Zinc-rich paints such as Zinga are very good, but can have overcoating issues.