Galvanized Raised Beds

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On a thin zinced corrugated sheet the zinc does offer some protection even if the edge is cut, paint gives no protection in that case. Painting the cut edge gives some protection but I doubt the paint lasts the abrasion if it is pushed into ground.

On heavy construction anodic protection is sometimes used, on short stints usually not, 12 mm of steel can take some corrosion.

How about a stone wall?
To make it more complicated you can’t just slap paint onto galvanized metal. For it to stick the metal needs to be “pickled” first.
 
For it to stick the metal needs to be “pickled” first.
Yes, passivated there are several ways of doing, treatment with phosphoric acid is one of the best. Some people leave it outside for a while and it gets slowly carbonized.

Thin sheet metal is actually almost always hot dip zinced not galvanized.

(Slightly pedantic engineer here.) :)
 
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Yes, passivated there are several ways of doing, treatment with phosphoric acid is one of the best. Some people leave it outside for a while and it gets slowly carbonized.

Thin sheet metal is actually almost always hot dip zinced not galvanized.

(Slightly pedantic engineer here.) :)
When I was still doing it for a living in The Air Force we usually used vinegar. But that was well over 20 years ago so Idon’t know what’s currently being used. To be honest, I never ran across a galvanized aircraft part. We usually had to do this when working on bits around the shop.
 
Zinc acetate is soluble in water which does not make it a very good base for painting. Looks like quite a few of the organic salts a soluble too.
 
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But there are loads of different paints available that are supposed to be used on zinc plated steel.
From spray stuff like this

to paint on like this one meant to repair the coating when the metal has been cut or welded.

He's only going to use it for the garden beds, it's not something that'll be on show, iimmc ?

M
 
Look like stock tanks (livestock water trough), pretty cheap in the US. Not so much here if can find them. Maybe farmer suppliers?
 
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To be honest Mary, zinc rich primer is standard for ALL metal (Zinc chromate was our general issue primer in the Air Force) But whether it looks good isn’t the point. The reason for painting this would be to deter corrosion. Unless the paint sticks—-it won’t do that.
 
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Look like stock tanks (livestock water trough), pretty cheap in the US. Not so much here if can find them. Maybe farmer suppliers?
Water troughs were my first thought when I saw them as well. Not so sure about the price though.
 
Many hot dip zinced parts are treated with a solution that has some oil in it that is poison for painting. It has to be washed off somehow.

Zinc containing paints of primers are neant for untreated (and clean) steel surface to give it better protection than pure paint would.

And after all this as you said it is only a garden bed.
 
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