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Old 01-30-2009, 03:45 PM   #1
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*Painting an un-painted galvanized roof*

Hi there,apologies if this topic has been discussed before as this is my first post, so here goes....

Im looking at painting my roof,it has never been painted before although it is fairly old.There are spots of rust here and there but not alot and by the looks of things,its only surface rust.Now Im wanting to know whats the correct procedure to prep the roof for painting.

So far these are the things we have bought: Blackguard(this is a rust converter product)
:30secs Outdoor Cleaner(this is a concentrate bleech-like product which contains 50g/L of Sodium Hypochlorite)
:British Paints Steelite roof paint (this is a self primer top coat paint which says on the bucket that I dont need to prime my roof,even if it hasnt been painted before??)......

Now,how would one go about preparing the roof for paint and would it be a good idea to buy an actual galvanized primer before applying top coat,even though the top coat is self priming? .....Ive read somewhere that the white substance you see on galvanized roofing will help adhere the paint to it so its not advisable to clean it off,so they suggested to spray rust converter on rust and then paint straight over it Huh .There is also some black silicon on the roof which was put up there to seal a leak,I hope this is paintable...


Last edited by Toymit; 01-30-2009 at 04:03 PM.
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Old 01-30-2009, 04:42 PM   #2
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Galvanized procedures may vary...

If you've decided on a top coat product (sorry I'm not familiar with the ones you mention), the best course of action is to contact the manufacturer
I would call them (if they don't have a tech line, don't use the product) rather than rely on can or website instructions


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Old 01-31-2009, 05:53 AM   #3
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Judging from the product selection, I'd say you are not in the US. I don't know exactly what is available to you if that's the case. However, I'll say that your prep sounds about right though I'd remove any loose particles on the roof. Any powder will cause the paint to fail. Galvanized surfaces are especially tricky. You need to remove any chemical residue from it. The zinc coating on a galvanized roof makes anything hard to stick to it. Since it's had time to weather quite a bit and you plan a good cleaning I don't think you'll have a problem with adhesion. The black silicone is a problem. Nothing really sticks too well to silicone. Are you sure it's a silicone sealant or is it perhaps asphalt? The product you selected for a top coat is thankfully acrylic. Acrylics will work best on galvanized. Oil doesn't like it too much. Acrylic should stick to a well weathered asphalt patch as well if that is what is sealing those leaks. Personally I'd use an acrylic DTM rust inhibitive primer before painting despite what the paint says.
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Old 01-31-2009, 10:34 AM   #4
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painting a galvanized roof

There are primers available through mainstream retail outlets made specifically for galvanized surfaces. I would apply the primer before moving forward with a topcoat. Also, caulks made with 100% silicone can't be topcoated with paint. The paint will simply bead up and eventually slide off the silicone. There are other products on the market with silicon type qualities tat will accept a top coat however.
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Old 02-01-2009, 03:24 PM   #5
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Thanks for replies...(btw Im in New Zealand) I rang British paints and inquired about the paint I bought of theirs, the tech reckons I dont need to prime the roof maybe just the bits where Ive used the rust converter incase it reacts with the top-coat (they reckon 3 coats all together).They were not farmiliar with the rust converter I bought (even though its a popular product here in NZ) as I told them it is self-primer too. As for the black silicon sealant,Im not sure if it is silicon I just assumed it was,it was put on the roof before we moved in,mustve had a leak prior.
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galvanized , paint , preparation , roof , rust

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