Classic cars forum & vehicle restoration.

Old-Nail · Joined: 23 Nov 2007 Posts: 853

Has anyone here ever painted galvanised steel? And if so does it take well or do you need special prep?

47p2 · Joined: 24 Nov 2007 Posts: 2009 Location: Glasgow

O-N, you will need to use special paints and primers for galvinised metal.
Personally I have found the paint does not adhere to the metal very well and it flakes off after a while
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Old-Nail · Joined: 23 Nov 2007 Posts: 853

Thank you.

My chassis is galvanised steel so I was wondering whether to paint it or not, I suppose rather than incur the extra expense I should leave it alone and paint just the suspension parts etc.

Uncle Joe · Guest

Theres a for me interesting thing here. If the people that galvanized your chassis in the first place had been bright enough, then they would have painted the chassis as soon as they could after treatment.

What happens later is that an oxide forms on the surface, making it difficult to paint. Paint will stick to a galvanized surface, but not to the oxide.

Some will tell you that you can wait until the surface has weathered, and then it will be possible. It would be, if we lived in a world that didnt have airborne pollutants.

The correct method to paint would simply be remove the oxide, then use a latex (water based!) paint....it is possible.

So to all intents and purpose, 47P2 is spot on....

Rick · Site Admin Joined: 27 Apr 2005 Posts: 22472 Location: UK

when I was talking to the paint guy about the Dodge a few weeks back, I asked him a similar question - the new sheeting I have for the back is Zintec, ie a zinc-coated steel similar to galvanised, and yes that too needs to be pre-treated before painting, otherwise the paint will flake off too.

If you want me to ask him about pre-treating a galv chassis, just let me know

RJ
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Uncle Joe · Guest

You only need to ask me Rick!

Galvanised surfaces are blasted in a specific way with crystaline iron titanium oxide, with a grain size of max 0,4mm. Doesnt everyone know that? Laughing

Greeney in France · Posted: Mon Apr 14, 2008 3:30 pm Post subject:

Finnigans (the hammerite people) supply a special water based primer paint to cover galvanised before you paint with hammerite
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Uncle Joe · Guest

Funny thing is, I welded up some galvanized pipe this morning for a chimney....and thats going to need painting! Laughing

47p2 · Joined: 24 Nov 2007 Posts: 2009 Location: Glasgow

Old-Nail · Joined: 23 Nov 2007 Posts: 853

The Hammerite solution sounds good - I'll do some investigating!

Uncle Joe · Guest

I assume the paint that Greeney is referring to is the one they call Special Metals Primer. The question the question that should be asked is, can this be coated with anything, not just Hammerite?

Greeney in France · Posted: Mon Apr 14, 2008 6:09 pm Post subject:

Yes it is just a Special barrier primer paint, I have used it for all sorts of paints and they are still stable
We was talking 2k paints yesterday, 2k etch or wash primers are good too
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Greeney in France · Posted: Mon Apr 14, 2008 6:18 pm Post subject:

Forgot to mention too if you really want to got he whole hog so to speak powdercoating is the best method to cover galvanised steel it will last for years
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Old-Nail · Joined: 23 Nov 2007 Posts: 853

I envisage one day finding the classic of my dreams, having a large heated workshop and very deep pockets, then I would... *POP*!.....my fantasy Is interrupted and I realise that I don't have any of those things....and Hammerite it is then! Laughing

Uncle Joe · Guest

Thats what we all envisage O-N, not just you!

Back to the topic, on the little job that I will be doing, irrespective of the type of paint I use, I still think that I will do a sweep blast of the surface. Better to be safe than sorry! Though I will admit, in this particular case, it doesnt matter much if it flakes....