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Panels in bare metal/zinc primer

Posted: Thu Aug 23, 2012 11:21 am
by singleton
Hello all just a question really, as I am working through my panels I have took wings etc to bare metal then zinc primed them, are they ok to be dry stored any length of time like this? I understand normal primer would surface rust but I am led to believe zinc primer wouldn't allow new rust development? I am in the process of stripping a mint wing at the moment and it's taking a while, going to zinc prime it at the weekend, how long can panels be left with no coating?

Re: Panels in bare metal/zinc primer

Posted: Thu Aug 23, 2012 12:57 pm
by rayofleamington
standard 'grey primer' offers little or no corrosion protection and primer is usually porous.. Therefore you are right to be careful. If you start to see corrosion, then it's too late and you need to strip & re-prepare.

Your zinc primer will give a fair degree of protection depending on how good it is and how well it was applied (don't take that personally!). The relative humidity prior to application and the surface keying can make a big difference.

I'm no car-paint specialist (at all) but have specified and tested zinc rich primers for offshore equipment (oil platforms etc..)
Some of the high protection primers need to have a very rough keyed surface as they can be brittle. These work very well if done properly but are worse than useless if done wrong (e.g. the paint peels easily and has a tendency to trap water under the paint, accelerating corrosion rather than preventing it.)


There's a wide choice for vehicles, but if yours was a self-etching primer then less need to worry about surface key.
The zinc works in a sacrificial way so the more there is the better, although it is a trade off against toughness etc..

If the paint is porous, then you're stuck - I've heard that a thick porous primer likes to soak up moisture from air humidity - the trapped moisture then gives issues for top coat adhesion etc..
On the flip side, some replacement body panels have a black non-porous paint coating which allows long shelf life, but that rarely makes a good primer surface.

Some bodyshops recommend a couple of days max between primer and paint - some DIYers have got away with a LONG time.

What does your paint manufacturer say?

Re: Panels in bare metal/zinc primer

Posted: Thu Aug 23, 2012 1:02 pm
by perkinsp3
Hi all
I'd be interested to know as well.
Hopefully going to start on my panels in a month or two but will probably be a year or so before i can get the whole car properly painted.
What can you recommend for protection during this time as my garage gets cold and damp over the winter
Thanks
Pete

Re: Panels in bare metal/zinc primer

Posted: Thu Aug 23, 2012 1:10 pm
by tysonn
Put them in the lounge.

Re: Panels in bare metal/zinc primer

Posted: Thu Aug 23, 2012 11:36 pm
by chickenjohn
Get some cheap ready mixed colour industrial paint from your local paint supplier, preferably of the same type of paint as you intend to use. (eg cellulose). Spray the primer panel with one thin coat and this will protect your panels until you are ready to start paint prep.

Re: Panels in bare metal/zinc primer

Posted: Fri Aug 24, 2012 1:00 pm
by perkinsp3
tysonn wrote:Put them in the lounge.
:D i'm guessing you're not married tysonn :D

Thanks chickenjohn.
I don't have any spraying equipment. I'll ask at the paint supplier what they can offer

Cheers
Pete

Re: Panels in bare metal/zinc primer

Posted: Fri Aug 24, 2012 5:01 pm
by tysonn
Been married 43 years mate.