nick205
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| posted on 22/7/22 at 08:05 AM |
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painting galvanised steel - what paint?
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?
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snapper
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| posted on 22/7/22 at 09:39 AM |
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The zinc is sacrificial, if you wanted to paint it then etch primer first the the top coat or a Hamerite type paint.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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nick205
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| posted on 22/7/22 at 01:28 PM |
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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!
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SteveWalker
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| posted on 22/7/22 at 03:54 PM |
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There's certainly Youtube videos of people preparing and painting galvanised Landrover chassis - a search for that may give some useful
information.
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Grimsdale
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| posted on 27/7/22 at 08:25 AM |
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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!
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indykid
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| posted on 27/7/22 at 01:01 PM |
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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 
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mcerd1
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| posted on 27/7/22 at 09:25 PM |
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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:
Originally posted by indykid
To the OP, suggest to your neighbours that they invest in some 12" trellis and some clematis
my thoughts exactly, but maybe a mixture of clematis, jasmine and honeysuckle
or maybe something tasty like a bramble (blackberry) - I have two, one called fantasia that produces tons of massive fruit and has massive thorns
(good security fence, probably as effective as covering the whole fence in barbed wire)
the other one is called Oregon thornless, more decorative and small but very tasty fruit
or forget the trellis and just plant a hedge - maybe bamboo if you want tall and it fast (just make sure you have some barriers in the ground to stop
the roots spreading too far - it will take over)
pyracantha if you want something spiky or you could go for something edible like juniper, hazel etc.....
after a couple of years you'll forget the fence is even there and the plants will also help absorb some of the noise too
-
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StevenB
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| posted on 1/8/22 at 12:36 PM |
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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.
*
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