permaculture

["John Cropper" <j.cropper@trinidad.net>]

I am sorry to have to advise that Mr. Cropper was unfortunately killed
earlier this week during a break in at his home.  Please unsubscribe him
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Thank you

----- Original Message -----
From: "Bob Howard" <rmhoward@omninet.net.au>
To: "permaculture" <permaculture@franklin.oit.unc.edu>
Sent: Wednesday, December 12, 2001 3:30
Subject: Re: PVC/galvanized


>
>
> Michael Dean wrote:
>
> > Howzit,
> >
> > Can somebody explain to me why --"Never use lead head nails as fasteners
on such a roof; alternatives: stainless steel screws, also galvanized screws
and nails with neoprene washers"
> >
> > Cheers Mike.
> >
>
> Corrosion is the short answer -  Lead and zinc have different electrical
potential and when water acts as a conductor between them an electric
potential is set up and one will corrode
> the other. This is a general problem with most metals. It is generally
unwise for different metals to be in contact especially where there is a
risk of water being involved. (Tho' I'm
> not sure about why stainless steel is OK on galvanized roofs %-)
>
> Bob
>
>
>
>
>
>
>
> ---
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