Rust bleed

[roh]

Hi

I'm seeking advice on trying to stop rust bleeding through from the rubbing strake. It's made from a galanized half round rubbing strate screwed onto a teak profile, this has traditionally been painted white. Last winter I stripped it all down and treated with the correct primer's / undercoat and topcoat all from Mr International's paint emporium.

Three months into the season and the rust is showing through again !!

I don't want to rip off all the galvanised rubbing strake (36ft boat) and getting new made as funds are tight with all the other work going on. So I was thinking of stripping all the paint off again and then applying a coat of epoxy which would then painted white.

Has anyone any experaince of getting rid of rust bleed in this way. Or does anyone have any other good ideas.

 

[mickshep]

Hi Dick.
from your post I gather that you did not remove the steel strip before recoating. I think you will find that the problem is caused by moisture trapped behind the metal, between it and the timber. Sadly in my experience the only cure is to remove the metal allowing the timber behind to dry in the process (No bad thing anyway).
Once removed the metal strip can be regalvanised quite cheaply before replacing on a decent sealant. Whilst it is off I would also be tempted to fill the old screw holes with wooden plugs, by reversing the metal strips the fastenings would be into new wood. Whilst the rust weeping is unsightly, I would be more concerned about the chance of rot starting behind the steel now water has lodged there. Any paint applied in situ can only seal water in and will only protect the metal whilst undamaged. Galve' on the other hand will take a lot more abuse and will self-repair to a degree. Goods luck! Mike.

 

[Peterduck]

I concur with everything that Mike has said. If you feel that the cost of re-galvanising is too much [and for the protection it gives it ain't] then recognise that you'll be wasting your time unless all [and I really mean all] of the rust is removed back to bright iron or steel. The galvanisers do this with a really savage chemical bath. Epoxy is a possibility on the side faying to the timber backing, but it won't cope with being knocked around against piles, etc on the outside. Better to galvanise the steel strips and epoxy the timber behind them.
Peter.

 

[Mirelle]

I also agree with what Mike says. It will do the job - nothing else will.

 

[roh]

Mike, Peter

Thanks for the advice, I think that removing the old galavnised strip is the only option. As you mentioned the chance of the teak rotting behind the metal will be greater by covering with paint / epoxy, taking the galv strip off and allowing to dry out will also allow me assess if there is any further damage.

I'll add the job to the others for this winter !!

Have a good new year

 

[AndrewB]

Agree with others - you haven't a hope of stopping the rust bleed unless you get this strip off and clean off the rusting by blasting, grinding or wire-brushing. And it will not be doing the wood underneath any good at all. Old galvanised fittings in time seem to be worse to maintain than plain mild steel ones.

Unless you get this fitting absolutely spotlessly rust-free, you are wasting you time (and money) with epoxy paint. Try red primer and a conventional polyurethane system. If it gets scraped, a quick touch-up is easy enough. It'll still have to be done again periodically, but you should get up to 5 years - you won't do any better by regalvanising and paint is a lot cheaper.

 

[tcm]

well it's been screwed in with A2 or worse screws instead of a4, probably. Patch all you like but until you sort out the source it'll always bleed rust.

 

[oldharry]

Stainless takes a galvanized coat off almost faster than it can be put on. If the strip has been fastened with Stainless it will rust - and within weeks of re-galvanising will start rusting again!