Gelcoating over galvanised metal or should I just paint it

[stuartwineberg]

The helm door frame on my Hardy is heavy galvanised metal encapsulated in a thin layer of gelcoating. The coating has split away at the bottom of one of the uprights exposing about 4 inches of frame. Hardy give you a big tin of gel coat for repairs so one option is to plaster gelcoat over the bare metal but how do I make it stick and how to make it smooth? Alternatively should I just seal the end of the broken gel coat to the metal with epoxy to make it watertight and then paint the metal white. If so, what kind of paint sticks to galvanised surfaces?

Thanks as always

Stuart

 

[Danny]

[ QUOTE ]
...and how to make it smooth?

[/ QUOTE ]I've only done two reasonably successful gelcoat repairs (and a few of the other sort!). In both cases I used some stiffish plastic to cover the repair while it hardened. I wiped the plastic with vaseline to avoid it sticking, made sure that there were no air bubbles and that the gelcoat was flat and fair with the surface around the repair and held it in place with sticky tape. Needed very little finishing afterwards. Maybe a bit amateurish but it worked for me.

 

[PCUK]

Whatever you do, You will need a metal primer for galvanised metal. Probably a zinc primer derivative.

 

[MM5AHO]

Galvanizing is one of the most problematic surfaces to get any coating to adhere to.
I'd recommend a phosphate pretreatment, preferably zinc phosphate, dry well, then coat.

 

[VicS]

I agree with the suggestions that the galvanising must be primed with a primer for zinc but one intended for use under paint is unlikely to be suitable for use under gel coat. You would have to take advice from the gel coat manufacturer.

Are you sure it is gel coat. An epoxy coating would be more likely i would have thought, more suitable anyway. Even a chlorinated rubber perhaps. Whatever you use you must use the appropriate primer for the galvanising.

 

[stuartwineberg]

Thanks. Epoxy sounds stonger and more likely to adhere anyway. Can you get it in white?

Cheers

Stuart

 

[stuartwineberg]

Spoken to Hardy and turns out that the frame is aluminium section with powdercoating. Must admit to being a bit surprised at this on a boat of this quality, doesn't sound marine grade to me and Hardy have replaced them with gelcoat covered GRP for new boats. So the answer seems to be rub down, prime and paint

Thanks for your help

Stuart

 

[VicS]

I nearly suggested powder coating. I guess you wont be wanting to remove it and get it redone but it is apparently not as expensive as one might imagine.