Order of Painting and Sikaflex?

[Roach1948]

Now my chainplates (galvanised) are on the outside of the hull I was pondering the plan of action for painting the hull.

I have white undercoat at present, but would like to hide the chainplates by painting them white too. My question is a) Do I fit the chainplates now (bedding with white Sikaflex 291) and paint over them with all topcoats hoping I don't make runs and that the paint sticks to the little bedding that squidges out the sides of the chainplates..... OR B) Bed chain plates in after hull is painted with them being painted individually beforehand and hope bedding does not become too conspicious to my particular hue of off-white?

 

[fluffc]

Sikaflex them on and paint over. I haven't had any problems getting enamel primers and paints to stick to the stuff.

 

[mclark]

Best to use special etch primers for galv, I think zinc chromate is the one but I might be mistaken.

 

[fluffc]

I was refering to the Sikaflex.

 

[Mirelle]

Yes, Sikaflex first.

In my experience, Sikaflex bonds to paint better than paint bonds to wood, so if you do the Sikaflex after painting it may pull the paint off.

Er...don't ask me how I know that.... /forums/images/graemlins/wink.gif /forums/images/graemlins/blush.gif

 

[Roach1948]

Really, I was going to paint straight over them? Won't the etching affect the zinc coating? Theare is already quite rough anyway - etch priming is something I did not consider!

Anybody have a favourite etch primer to recommend?

 

[Roach1948]

Thanks Mirelle - Chainplates going on first then!

 

[mclark]

Although the finish on a galvanised object is rough I gather that paint does stick significantly better if you use a primer. Certainly I worked on a construction project once, a steel bridge which was galvanised and the painters had been forced to apply two coats of etch before any undercoat/gloss.

 

[Peterduck]

Etch priming is really only necessary if the galvanising is new and shiny. Once the zinc has weathered to a dull matt grey you can just paint straight on it.
Peter.