[TowerTalk] zinc chromate, was Aluminum radials

[K8RI on Tower talk]

>
> Yes I have heard of this. Years ago when I used it I think it was called
> zinc chromate and was a primer for aluminum. This maybe different to what
> you refer to, but I have also seen the stuff in aircraft and surplus
> military radio gear( the jungle proofing was different) on Al panels. I
> don't think it would survive the direct burial test because somewhere it
> would be scratched and breakdown at that point. I've never seen a
> conductor with this type of coating but it maybe in use somewhere. ;-)
>

The Chromate family of primers are indeed difficult to find and impossible 
in many areas.
I was still able to find some two years ago to do some touch up on the 
Debonair.

The etch used on Al is Phosphoric Acid and can be fairly dilute.  It does 
take a thorough washing though which would make it poor for stranded Al.

The Phosphoric Acid etch followed by the wash and then Chromate primer does 
a very good job on airplanes.  The primer can be replaced with alodyining 
after the etch but is a lot more involved.

Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com