WHy Zinc primer?

[boatster]

I have never got a satisfactory answer for why we need to use zinc primer when repainting outboards.<br />Is it because the zinc in the primer oxidizes onto the aluminum? Or is it something else? What happens if I use regular primer on a clean aluminum outboard for repainting? Can someone clear my head on this matter? Thanks.

 

[JB]

Re: WHy Zinc primer?

Not zinc, boatster, Zinc Chromate. Because it bonds to aluminum and aluminum alloys and seals the surface from oxidation.<br /><br />Your finish paint will then bond to the primer.<br /><br />"Regular" primer will not bond to those alloys.

 

[Paul Moir]

Re: WHy Zinc primer?

Just a couple additions to what JB is saying:<br />It's for that corrosion protection and boding that they use it on just about all commercial airplanes as well. It is possible to use epoxy primers but they don't provide any corrosion protection. Unless you use one of the $super-high-tech$ $military$/$aviation$ "Fluid resistant" primers that is.<br />Around here, it is very hard to find real zinc chromate primer due to its nasty health effects (work outdoors with the correct resperator!). So usually we have to settle for zinc phosphate aluminium primer.

 

[Dunaruna]

Re: WHy Zinc primer?

Originally posted by Paul Moir:<br /> Around here, it is very hard to find real zinc chromate primer due to its nasty health effects (work outdoors with the correct resperator!). So usually we have to settle for zinc phosphate aluminium primer.

That's because it has officially been categorised as a carcinogenic. It is being (slowly) phased out all over the world, including the U.S of A.

 

[boatster]

Re: WHy Zinc primer?

Oh Wow!! Scary but good info to have. Thanks guys.<br />I'll be sure to wear my respirator outside when I use the zinc chromate primer.

 

[Paul Moir]

Re: WHy Zinc primer?

Ah, the US are loosing it too then eh? It still seems to be pretty prevalent when it comes to aircraft, but I'm sure there's good reasons for that. I had noticed the carcinogen warning, but my senses have been dulled by Proposition 68 (or some foolish law from somewhere in the 'States where they label literally everything as carcinogenic).<br /><br />Sorry for drifting a little off topic there boatster!

 

[Dunaruna]

Re: WHy Zinc primer?

I think this is definately related to the original topic.<br /><br />The subject came up about 6 months ago, I did quite a bit of research and found - some states have got total bans, some states have got partial bans. The aircraft industry still use it because the technicians are highly trained and use appropriate measures. To date, there isn't a product to replace it 100%.<br /><br />If wallyworld sold it, every second homehandyman would be suing - especially now that it is proven to be carcinogenic.<br /><br />like you said, proper masks and maybe even a tyvek suit - no problems.

 

[dingbat]

Re: WHy Zinc primer?

Any good industrial supply store should carry it.

 

[boatster]

Re: WHy Zinc primer?

<br /><br />So would any other metal primer just not work at all? I've sprayed a kicker with Rust Oleum Painters Touch Primer. It seems to be holding ok.