Morning all,

There's a railway line at the end of mine and my neighbours back gardens.

A few years ago Railtrack came along and installed a gavlanised steel anti-trespass 6ft chainlink fence with an angled top with barbed wire behind everyones existing garden fences. No real issue as most people in our street have 6ft fences anyway.

My neighbours and I have 5ft fences so can see the top of the Railtrack fence. Neighbour to one side went and painted the top of the Railtrack fence with black paint. Neighbour the other side did it in green. I really wasn't that bothered/couldn't be arsed so didn't paint anything!

Both neighbours sections now look a mess, because the paint has just flaked off and left a galvanized/coloured patchwork!

Can you actually paint over galvanizing?

If so what with - primer/top coat etc?

The zinc is sacrificial, if you wanted to paint it then etch primer first the the top coat or a Hamerite type paint.

Thanks snapper handy to know.

I don't think I'll be painting my section any time soon, but handy info to pass on to the neighbours!

There's certainly Youtube videos of people preparing and painting galvanised Landrover chassis - a search for that may give some useful information.

my recommendation is don't paint it. No matter how hard you try, there will always be a little paint defect (known as 'holidays'. With a very reactive metal like zinc, it will rapidly corrode and produce voluminous oxide products which spall the remaining paint coatings.

For galvanising to be effective, it needs to be uncoated and have opportunity to dry. When allowed to dry it forms a zinc carbonate patina (passive layer), which protects the metal below. When left wet, such as when paint remnants trap water against it, it forms zinc oxide which spalls and exposes fresh zinc to corrode further.

I appreciate yours is only a cosmetic concern and the life of the fence is not your primary concern, but I wouldn't paint a galvanised chassis!

Combining Grimsdale and SteveWalker's posts, we can perhaps conclude that much like powder coating, painting galvanised steel will begin to fail as soon as the surface coating is broken and the surface gets wet. People that have galvanised Landrover chassis' and paint them are probably the people that never get their Landrover wet, so get away with it.

I've also seen Landrover body repairs carried out with stainless rivets (because stainless is obviously invincible so must be best) and the aluminium disintegrates around the rivets from the galvanic corrosion.

To the OP, suggest to your neighbours that they invest in some 12" trellis and some clematis

etch primer will work better than nothing -

but if you really want it to stick you need to 'sweep blast' it first
basically lightly sand blast it until it just looks a dull mat grey - this removes almost all the pure zinc layers and just leaves the harder zinc-iron alloy layers
(same idea as the etch primer but much, much more aggressive) - of course this also removes at least 50% of the actual corrosion protection as well....

quote:

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Originally posted by indykid
To the OP, suggest to your neighbours that they invest in some 12" trellis and some clematis

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If they painted it when it was brand new galvanised steel, the paint will flake off really quickly.

New galv must be T Washed first to prepare the surface for painting.