How to clean up and stabilize oxidized zinc aluminium roof sheets?

[megbenbow]

I have some old zinc aluminium sheets that have oxidised and rusted a bit .

have read that  household vinegar solution should clean up the oxide and perhaps the rust? Then should I spray with a rustoleum  grey non etch primer? 
doesn’t have to be perfect as it won’t be visible but I’d like it to be durable and look tidy 

[MitchellMc]

Welcome to the Bunnings Workshop community @megbenbow. It's terrific to have you join us, and many thanks for your question about treating Zinc roofing.

I note you've mentioned that it is zinc-aluminium roofing. Typically, roofing is zinc-coated steel. Are you able to confirm that the roofing is aluminium? I ask because aluminium doesn't rust; it corrodes, but not like steel rusts.

I suspect it would be zinc-coated steel. If so, you should scrub the area down with Sugar Soap and a Scotch-Brite pad to remove any oxidation. Flush with clean water. You can then sand the rusted area to remove any flaking or rough areas. If the rust is quite substantial, you can spray it with Rust converter, but you must apply it only to the rusted area and not to the Zinc coating. You might be best to spray some into the cap and apply it with a brush directly to the rust.

After that, spray the whole area with Dy-Mark 400g Silver Zinc MetalPro Primer / Top Coat. This is a primer and topcoat in one and should hopefully be a similar colour to your zinc roof.

Since it sounds like you'll be working at height, check out this helpful guide on How to use ladders safely.

Please let me know if you have any questions.

Mitchell
 

[megbenbow]

Thanks for the response .

Yes it’s zinc coated steel 

Today I tried a solution of cleaning vinegar and detergent and scrubbed both sides of sheets with soft brush.all the dirt came of  but little of the oxide.However if left on for a couple of hours the white oxide was dissolved ( I assume ) It’s probably lost the zinc coating and is down to clean  steel.Which I again assume is better than an oxidised surface . I was thinking of painting all the front facing sheets with the rustoleum primer mainly because I like the colour and the Matt finish. Does it have to be over coated .?I really don’t want a glossy finish ..unless perhaps there is an oil boiled Linseed perhaps?…also I would like a uniform finish and I have 10x1500x900 sheets to paint so I don’t think a spray can or three will be enough I will get some rust converter and apply as suggested  First 

[megbenbow]

No im not working at height ,can do all the prep work on the ground. I have a can of zinc pray paint left over from an earlier task .i will test that out and see if the colour match is homogenous. If so I might get away with a patch job. 
thank you 

[EricL]

Hello @megbenbow 

I'm afraid using just primer is not enough to protect the surface of the roof sheets. I propose looking at the White Knight Rust Guard Medium Grey Metal Primer Paint - 1L and using White Knight 1L White Flat Rust Guard Epoxy Enamel Paint which comes in a flat finish and can be tinted to different colours. I also suggest investing in an electric paint sprayer such as the Ozito 400W Power Paint Spray Gun to make the painting much easier.

If you need further assistance, please let us know.

Eric