Why paint zinc? - non boaty

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richardabeattie

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Sorry but where else can I turn to for the sort of expert advice this forum provides?

I have an ornamental canopy on the front of my house which is clad in zinc sheeting The old paint has failed and I have stripped it back to bare metal. The metal is thin and presumably flexes a bit as it heats and cools - it gets a lot of sun. So my questions are:

Can bare zinc be left like that or will it corrode?
If it must be painted what undercoat and topcoat would the forum recommend?

Thanks
 
richardabeattie said:
Sorry but where else can I turn to for the sort of expert advice this forum provides?

I have an ornamental canopy on the front of my house which is clad in zinc sheeting The old paint has failed and I have stripped it back to bare metal. The metal is thin and presumably flexes a bit as it heats and cools - it gets a lot of sun. So my questions are:

Can bare zinc be left like that or will it corrode?
If it must be painted what undercoat and topcoat would the forum recommend?

Thanks
Click to expand...
The idea of zinc is that it doesnt need painting! However peeps do. Zinc plate doesnt like being painted, ask someone else with chemical knowledge why. However I would use a metal primer coat followed by PROPER oil paint.
Stu
 
skipper_stu said:
The idea of zinc is that it doesnt need painting! However peeps do. Zinc plate doesnt like being painted, ask someone else with chemical knowledge why. However I would use a metal primer coat followed by PROPER oil paint.
Stu
Click to expand...

To bring this thread back to sailing, I actually paint my galvanised Delta anchor white - it means I can check its set more easily in clearish waters where I sail, and I can also find it more easily after a scuba-dive so I can come back up the anchor chain.

I painted it with about four coats of zinc metal primer, then a couple of coats of enamel. It has stood up well so far to two seasons of anchoring.
 
If it is zinc sheet and not galvanized iron, leave it. It gets a slight oxide then stops, new zinc is shiney, then goes a dull grey. All flashings on roofs (and some complete roofs) are made from it here. Never painted.
 
I have painted areas of galvanising on my boat trailer which are subject to being 'dripped on' by the hull, as being kept wet for extended periods had begun to cause white powder to form on the surface - the zinc was acting as an anode ! I used Zinc Phosphate primer - no problem applying, and no problems since.
 
richardabeattie said:
Sorry but where else can I turn to for the sort of expert advice this forum provides?

I have an ornamental canopy on the front of my house which is clad in zinc sheeting The old paint has failed and I have stripped it back to bare metal. The metal is thin and presumably flexes a bit as it heats and cools - it gets a lot of sun. So my questions are:

Can bare zinc be left like that or will it corrode?
If it must be painted what undercoat and topcoat would the forum recommend?

Thanks
Click to expand...

Whatever you do, don't paint Zinc with anything aluminium or alkaline.
 
My workshop door is a roller shutter type. It looked fine when new but weathered in two distinctly different appearances, top and bottom, presumably because the steel was galvanised differently in some way. I painted it using an etch primer, normal for zinc and aluminium to provide good adhesion. The one I used was by Hammerite. I then overcoated with a household paint to match the timber everywhere else. This door faces east, so rarely sees sunshine.

Opposite that is my double garage, also with galvanised doors. That one gets very hot at times. I painted it in exactly the same way and it is still in excellent condition about five years later.
 
In the good old days rainwater goods, gutters, downpipes etc were made of zinc and then often painted with a bitumenous black paint. For reasons - unknown!
In France recently, and very surprised that UPVC is unheard of, both windows and rainware use traditional wood for windows frames and zinc for rainware.
 
UPVC is not exactly unheard of in France, several outfits locally make windows etc.
But, as our house is old, the building licence for the barn conversion required zinc gutters and down pipes as well as old style tiles on the roof.

For the OP, the only reason to paint it would be cosmetic.
 
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