Painting Zincalume

[maglite]

Gday All,

After i have painted the zincalume with etch primer, will i need to add a coat of read lead primer or similar before i apply the finishing coats?

Not a lot of info out there and i dont want a paint job that is only going to last a couple of years and then turn gonzo.
I would rather do it properley in the first place.

Thanks in advance.
Steve

[silentC]

Hmmm, OneSteel don't recommend you use an etch primer at all on Duragal, which has a zinc coating. I painted mine with an oil-based metal primer from Norglass after cleaning it down with metho. Wattyl also has a system for metal that you could check out.

I think the thing with an etch primer is that it eats the zinc coating and renders it useless. Probably depends how thick it was to start with. The coating on Duragal is very thin.

[julianx]

I usually use white vinegar to clean the oily surface off new zinc,if its been in the weather for a few weeks it doesnt need it, just a good metal primer then top coat. I'm pretty sure silent c is right about etching.

[durwood]

What etch primer are you using there are different types?

Most available now don't have any acid in them which could hurt the zinc. They usually had phosphoric acid in them and a chromium base. These have mostly been withdrawn from the market due to environmental issues.

You can usually find the contents on the paint tin but the usual application for them called for a light coat which made the surface rough. By doing this it stuck and the following undercoats had a good non smooth surface to adhere too. Being put on lightly meant no eating of the surface took place, if you put them on heavy they fail as the surface dries soft and cheesy.

Modern good etch primers are marked CF or chromate free but the best primer for any metal not only for adhesion but also for added protection is epoxy primer (the best ones are two pack). It sticks to anything from stainless steel and even plastics and its best feature is its acid proof. It is what is usually put inside tanks to protect them if you are going to use them to store acids.

Wash the zincalume with metho and it should be ready to prime you can then use a suitable undercoat for the top coat you have chosen after your etch or prime coat.

Unless you really have a good reason keep away from red lead primer (RL Poisoning especially if you intend to rub the undercoats to produce a good surface for the top coats.

It will depend on what paint finish you chose as to how long it will last, what are you painting?

[echnidna]

AFAIK Wattyl Solargard is a good roof finish that doesn't need an etch primer plus its safe for drinking water tanks.

[Barry_White]

AFAIK Wattyl Solargard is a good roof finish that doesn't need an etch primer plus its safe for drinking water tanks.

Just wash it down first with Prepsol first and let the first rainfall go. If you don't you will end up with froth in your water tanks.

[soundman]

I don't know how good it is for drinking water but duragal is great stuff. designed specificaly for touching up welds on zinkalume and gal.

Sticks like the proverbial animal waste product to the proverbial fiborus warming device to just about anything.
Is realy durable and corosion resistant.

Did the bro inlaws boat trailer in it a few years ago & its still gleaming gleaming gleaming.

A number of the manufacturers formulate specilist roofing paints. Resene do a water based product.

cheers