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Painting on old galvanize

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Adrian 204/08/2020 13:19:43
82 forum posts
19 photos

I am considering stripping off the old paint on my up and over garage door, it comes away in ribbons revealing the old unbroken original galvanizing.

My thoughts are, thoroughly clean galvanize, etch prime, undercoat, top coat.

Is this the way to go? Any recommendations for best paint system welcomed.

Thank you.

Adrian.

David George 104/08/2020 13:43:08
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1302 forum posts
447 photos

Hi Adrian. Painting on galvanised steel is always a problem as the original paint peels of easy. What you are using is what I would use as you only do it once so do it the best way you can. You can get a two part epoxy paint to replace the traditional way but not having used it my self I couldn't recommend it.

David

Thomas Cooksley04/08/2020 13:46:41
32 forum posts

Hi Adrian, The etch primer is the key. Looks like it may not have been etch primed first time that's why it's peeling of. You may need to degrease the door before applying the etch primer. As for the top coat how about hammerite, available in several colours with a smooth or hammered finish. That's what I would do.

Tom.

Martin Kyte04/08/2020 13:47:01
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2010 forum posts
36 photos

Underseal.

)

Martin

Paul Lousick04/08/2020 14:04:33
1493 forum posts
568 photos

An etch primer is usually used on galvanized steel. Check with the makers instructions because some also require a normal primer over the etch prior to adding a top coat.

The surface must be completely cleaned of any previous paint because it contains an acid which reacts with the metal. It will not adhere to paint, fillers, etc.

2 part epoxy paint also requires priming first but if using, full PPE should be used as it is poisonous if inhaled.

Paul.

Clive Foster04/08/2020 14:08:28
2317 forum posts
76 photos

White, silver or other reflective light colour is best. Garage doors get hot in the sunshine and the constant thermal movement shifts most paints in time.

Hammerite tends not to be terribly good as the cover coat is too thick. New fangled worse than old fangled.

There is/was a so called "garage door paint" from, I think, International. Brush on. Not good in my experience.

Were I to do a metal door again I'd be tempted to use many thin coats having had some success with this approach for difficult things in the past.

Clive

JasonB04/08/2020 14:23:04
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Moderator
18628 forum posts
2048 photos
1 articles

Mordant solution is the traditional treatment for galv but there are several modern primers that will work such as Zinsser's "Bullseye 1-2-3"

KWIL04/08/2020 16:08:17
3289 forum posts
63 photos

You can also use a high zinc paint over the galvanised surface ZINGA (painted on) or Zingaspray. You can then use a sealer followed by your top coat of choice.

Adrian 204/08/2020 16:35:33
82 forum posts
19 photos

Thank you all for your ideas and advice, success hinges on that first coat of primer . I will gen up and make a selection.

Regards,

Adrian.

Baz04/08/2020 17:20:23
450 forum posts

Seem to remember that Hammerite do a speciality metals primer which works on galvanised, I purchased a tin before lockdown but cannot seem to find it at the moment, along with quite a few other things.

Nicholas Farr04/08/2020 18:12:21
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2405 forum posts
1188 photos

Hi, B&Q sell Special metals primer from Fortress and Hammerite, the latter being cheaper, but both pricey for their amounts. I can't vouch how good either of them are though. Special Metals Primers.

Regards Nick.

clogs04/08/2020 19:33:10
576 forum posts
12 photos

when we could only get plain galv corrogated iron sheets for roofs in S.Africa, when the colour'd was needed we use to wash the panels down with brick acid (whatever that is) then wash with clean water.....

Beware, it was a bit stinky .........

no prob with adhesion after that......we did use the proper roof paint tho...

dont know about Fortress paints but Hammerite will never cross my threshold ever agin.....pure rubbish.....

actually Screwfix's hammerite is / was OK when I last used it.....

Keith Wyles04/08/2020 20:10:11
35 forum posts

Galvanized sheets generally take paint a lot better after they have weathered for some years. i assume that using acid simply speeds this up.

Pete White04/08/2020 20:22:08
93 forum posts
7 photos
Posted by JasonB on 04/08/2020 14:23:04:

Mordant solution is the traditional treatment for galv but there are several modern primers that will work such as Zinsser's "Bullseye 1-2-3"

That is good stuff, makes paint stick better than "anything" to blanket !

Yes I also believe, from my Landrover days, that hammerite do a primer for galv and ali.

I few months ago I painted a double up a over door in a paint by "Bradite", quality stuff. I am no painter but it went on a treat, one coat of a light green over purple, no runs. Very optimistic that it will perform well. My paint brand of choice now.

pete

Hopper04/08/2020 23:24:52
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4768 forum posts
104 photos

Rubbing galv down with vinegar can help etch the surface to help paint stick.

Sam Longley 105/08/2020 10:02:22
774 forum posts
26 photos

Although I have not tried it myself; My painting contractor & some of the members of the yachting forums(for keels) recomend one of the Dulux weathershield products.- metalshield primer etc

 

 

Edited By Sam Longley 1 on 05/08/2020 10:05:09

Brian Oldford05/08/2020 10:11:07
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684 forum posts
18 photos

T Wash is the stuff to use. Used extensively as body preparation by many heritage railways.

**LINK**

duncan webster05/08/2020 10:41:09
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2733 forum posts
40 photos

You can't get the old fashioned Hammerite any more, I never liked it anyway, easy to apply but seemed to chip easily after a few years. Unless you want the hammered look the modern stuff doesn't seem to have any advantage over Alkyd, it doesn't dry particularly quickly.

Swarf, Mostly!05/08/2020 10:41:36
534 forum posts
47 photos

Hi there, all,

I don't know what process is used for the galvanised sheet steel from which garage doors etc are made. Maybe it's an electro-zinc process.

I doubt that it's a hot dip process unless it is configured rather in the shape of a float glass plant.  (Long and narrow and hot in the middle! )

The following is my understanding about hot-dip galvanising - I welcome correction from any members with first-hand experience. I understand that hot-dip galvanisers float a thin layer of molten palm oil on the surface of their molten zinc vat/bath. When the item is removed from the bath it gets coated with a film of palm oil on top of the zinc - it is this that makes the item difficult to paint until the weather and any passing microbes have removed it.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 05/08/2020 10:43:00

Mike Woods 110/08/2020 09:22:06
31 forum posts
1 photos

+1 for Zinsser Bullseye 1-2-3, followed by Zinsser AllCoat white satin exterior paint. I did my garage door 18 months ago using a small brush for the seams and fiddly bits and a small gloss roller for the rest. I was impressed by the the finish, ease of application and no messy clean up afterwards.

I was dubious about using water based paint at first so did a trial on some of old and new galvanised sheet scraps. Even just 24 hours after application it was very difficult to remove by scraping, but after curing for a week or so it was nigh on impossible to remove. I guess time will tell, but so far, so good.

Since then, I have started using water based paints on interior woodwork.

I have no links to Zinsser, just another DIYer with a paintbrush in hand.

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