painting Galvanised Steel

I have made a wind vane from some galvanised steel sheet and mild steel rods and tubes etc. I guess that I should use an etch primer, but would an acid etch with sulphuric or phosphoric acid be just as good or better. Not too fussed about the final paint finish, but once installed, don't want to go onto the roof to re-paint it often. I believe you can mix Jenolite into oil paints to make your own etch primer.
BobH

Most good paint suppliers will supply a ready made etch that works on galvanised, I know our local painting suppliers do, doubt whether you will get anything that’s any good in the DIY supermarkets, need a specialist paint supplier.

Dave W

Cold galvanising paint like " galvafroid". Made for the job

Apart from paint-on hi zinc paints as abocve, you can also get hi-zinc spray on that works very well. I have use this paint on galvanised gate hardware with good long term protection, even where the striker hits the latch.

Galvanised steel should be treated with mordant solution. This will turn it black and allow the paint to adhere. Duluth paints make it, as well as other suppliers.

Maurice

Interesting replies, I have used galvafroid, but it doesn't stick to galvanised steel. Now what is Mordant solution ? 10% Phosphoric acid, a touch of copper carbonate and a flammable "paint" mixed in it. Now I need to find out where and what they call it in France.

Thanks for the info.
BobH

On the farm we let galvanised metal weather bare for 6 months, then the oxidised surface held the paint quite well.

Regards

Richard.

We always used Galvafroid on galvanised conduit, over twenty five years since I had any involvement with that work though.

Edited By V8Eng on 06/07/2018 23:31:39

Edited By V8Eng on 06/07/2018 23:32:59

Edited By V8Eng on 06/07/2018 23:37:16

When proper functional coatings were available calcium plumbate was the 'go to' product.

Please note 'plumbate' indicates llead containing thus classified as Toxic.

Regards

Jerry

Mordant solution is sometimes called Mordant "T" wash. Depends on where in the country you are. I have painted galvanised Land Rover chassis after using the wash. Sold the last Land Rover now but all the time I kept it the paint stayed on.

To prepare the iron for painting if it's new, wash it with detergent in hot water to get rid of the oil.

Ian S C

Thanks all - I have found a tin of RUSTOL OWATROL on the shelf. It says its a rust preventative which can be used on zinc. I have used it in the past on rusty iron / steel with excellent results, so hope I don't have to shin up onto the roof to re-paint the weather vane too often.
BobH

Suitable primer available at branches of Castorama: **LINK**

Russell

Well Russell - That seems to fit the bill nicely. Thanks Bob

But note the safety warning - Dangereux – Respecter les précautions d’emploi. Dangereux = Dangerous, the highest danger classsification under REACH.

"Can cause sleepiness and vertigo" so be especially careful if you paint it up on the roof !
DaveD

I've tried Galvafroid on various Landrover parts in the past, but not found it very long lasting.

Rustoleum Cold Galv paint seems to work quite well.

Bill

'Hammerite' .... ?

George.

Hammerite does not 'stick' to galvanising George

I had a look and they do a special metals primer which includes galvanised and also a hammerite direct to galvanised paint **LINK**

pgk