Restoring and painting old corrugated "iron" / metal roofing sheets (galvanised)

[Oxbow16]

Hi

 

I was donated some "corrugated iron" sheets and have been using them for a couple of years in a makeshift shanty town style array to cover firewood. I want to build proper wood shelters before winter and plan to make use of these sheets. But I'd like to clean them up and protect them as part of the project. It doesn't have to be amazing, the main objective is just to make sure they last as long as possible.

 

I'm pretty sure the sheets are galvanised. There's some old black paint in them which has blistered, flaked and peeled in places. There's also remnants of an old orangey/rusty coloured paint on them which you might mistake for rust at first glance. That being said, there is some rust in places but they're not too bad overall.

 

Bitumen paint seems a common choice. What do you guys think to that? Or are there better alternatives? Also, would I need to use a primer or anything else prior to painting? I've read about rust inhibitors, etch primer, and various other things, some of which people say you should use on galvanised, while others say not to. So feeling a bit confused and hoping you guys can put me on the right path.

 

Many thanks

 

PS - I will be fixing them down properly. Please ignore all the wood and rocks!

 

 

 

 

 

 

 

 

 

[JohnMo]

Wire brush the old paint off, should come off easily. Then paint in high zinc content paint, often sold a cold galvanising. Not cheap but will last another few decades without being touch again.

[Conor]

Round here they paint them red oxide and leave it at that. I wouldn't rub down too aggressively as you'll remove what galvanising is left. 

[joe90]

Hamerite direct to rust paint is very good (just take of the worst of the loose rust off.

[Oxbow16]

Thank you all for the replies, much appreciated.  

 

15 hours ago, JohnMo said:

Wire brush the old paint off, should come off easily. Then paint in high zinc content paint, often sold a cold galvanising. Not cheap but will last another few decades without being touch again.

 

I've just had a look at prices and it seems it would be 1,000%+ on bituminous paint.  Ouch!  How much better would it be do you imagine?  And if the cold galvanising would last another few decades, how long by comparison would you expect bituminous paint to last?  

 

 

10 hours ago, Conor said:

Round here they paint them red oxide and leave it at that. I wouldn't rub down too aggressively as you'll remove what galvanising is left. 

 

Interesting that they use just that, as it is regarded a primer so seems odd to not put anything over the top.  I'll look into it further, thanks.  Comparable price to bituminous.  Thanks also for the tip.

 

 

5 hours ago, joe90 said:

Hamerite direct to rust paint is very good (just take of the worst of the loose rust off.

 

I'm getting spoilt for choice now    Seems about x2 / x3 more expensive than bituminous.  Do you think it is worth the extra outlay?  Longer protection?  

 

 

Cheers

[joe90]

17 minutes ago, Oxbow16 said:

Do you think it is worth the extra outlay?  Longer protection?

I could not say, but you get what you pay for so I would bet the obvious 🤷‍♂️

[Onoff]

The plus points stack up for good old black bitumen paint. Cheap, it'll fill pin holes and round the roofing screws. Easily to reapply too. On rusty steel it also has a protective effect as the oil seeps out. Probably the best chance of sticking if there's remnants of paint on there.

 

You can get a white bitumen.

 

A flexible acrylic like Acrypol, Chromapol, Evercryl etc is sort of made for the job but expensive. Easy to reapply but I'd worry about rust carrying on under the paint. 

 

Whatever I'd jet wash first. If you can, get the worst rust off and paint with a phosphoric acid solution before painting. It'll turn the rust to a stable black/grey. As in iron oxide to iron phosphate like Jenolite rust converter. 

 

 

 

 

 

Edited August 23 by Onoff

[Crofter]

Those sheets are a million times better than what I recently used to build a lean to wood shed. 

I slapped some denzo tape over the old nail holes, works surprisingly well.

Wouldn't dream of spending money on paint though 😂