Cold Galvanising

[Stemar]

I have an anchor which has been treated with a cold galvanising paint and, a few years on, is now well speckled with rust. It's a spare, but it fits in Jazzcat's anchor slot, so is exposed to the elements, but rarely gets used. To prep it for a fresh couple of coats of galvanising spray, do I just give it a quick rub down, or would I be better off giving it a dose of Fertan rust treatment first?

Proper regalvanising is out of my budget, just in case anyone's wondering.

 

[rogerthebodger]

Cold Galvanizing is no more effective than painting.

To get any paing to stick to steel is to give it grit blasted then paint before it can flash rust.

Th paint will still chp off when the anchor is used.

I own a steel boat that is painted with epoxy paint after grit blasting but still chips that will rust.

Th alternative is to acid wash with acid. I use hydrochloric acid then phrospric acid with a wash and dry before painting

 

[penberth3]

I have an anchor which has been treated with a cold galvanising paint and, a few years on, is now well speckled with rust. It's a spare, but it fits in Jazzcat's anchor slot, so is exposed to the elements, but rarely gets used. To prep it for a fresh couple of coats of galvanising spray, do I just give it a quick rub down, or would I be better off giving it a dose of Fertan rust treatment first?

Proper regalvanising is out of my budget, just in case anyone's wondering.

I'd go for brush paint, hard to build a up a good thickness with spray. Apart from that it's no different to any other re-painting job. De-rust as much as possible then do it. I wouldn't apply anything else, the zinc in the galv paint is giving the protection.

 

[DanTribe]

on building sites we used Galvafroid when galvanised steel was scratched or drilled, as good as anything but not perfect.
I once used epoxy tar on a rusty iron keel. It lasted many years but is now banned on health grounds. There may me a safer alternativ.

 

[rogerthebodger]

I once used epoxy tar on a rusty iron keel. It lasted many years but is now banned on health grounds. There may me a safer alternativ.

I used epoxy tar on the hull of my steel boat below the waterline and as long as it's overcoated on fresh paint it builds up a good thickness and is as impervious to water as anything.

I also used epoxy tar on a ferro cement boat with the same effect.

Epoxy tar is also spft and does not chip as much as epoxy paint

 

[awol]

Proper regalvanising is out of my budget, just in case anyone's wondering.

I dropped my anchor off with a local blacksmith/fabricator who added it to a load of gates and railings being galvanised. Cost was acceptable and a lot less than 2.5litres of antifouling!

 

[ducked]

On a car I've had good results abrading with aluminium (more freely available than Zinc) using sunflower oil as a binder. Linseed, Tung or alkyd resin are possible alternative binders. This has the advantages of being (almost) free and very easy.

Coke Can for Brake Drums

Havnt tried it yet in a marine context. I expect it'll be much less effective, but perhaps not completely useless.

I've seen reference to micro-electrophoretic galvanising on motorcycle forks using dead dry cell batteries, but havnt tried it. I would think if this is effective at all, it would only do for touching up small chips or abrasions, perhaps at the pointy end of an anchor.

You MIGHT find a welder who had kit for flame spraying zinc.

 

[Stemar]

Thanks, everyone. No Fertan, then. I know spraying it is very much second best, but the only time I could see me using that anchor is if we dry out on a beach and want to put out a stern anchor, and redoing it every 2-3 years isn't a big deal

 

[ducked]

I note some of the cable vendors are promoting some kind of hybrid zinc/aluminium finish (thinking I might re-rig with it or galvanised) which are supposed to be complementary, so maybe doing a galvanised anchor with aluminium might be quite effective.

I suppose I could add some dead dry cell casings to the aluminium abrading disk but dunno if I'm likely to bother,

 

[rotrax]

I used a Zinc Rich paint on our steel yacht in New Zealand. It clearly said on the tin 'Dont use after acidic rust converters/treatments.

I got it to bare metal by grinding/needle gun and used the Zinc Rich paint. Couple of days later, on with the topcoat. Worked well.

I have had good results with Smoothrite from Hammerite. Used it on a deck fitting that was showing red streaks. Nothing since I painted it.