[TowerTalk] Brown colored galvanized surface?

[Doug Scribner]

      From the following site:

      http://www.galv.co.uk/appearanceguide.html

      A thin brown surface staining sometimes occurs in service when the 
galvanized coating comprises entirely zinc-iron alloys as discussed under 
'Dull grey coating'

      1.Dull Grey Coating
      General comment:Acceptable.
      A dull grey appearance is caused by growth of the zinc-iron alloy 
layers through to the surface of the galvanized coating. Grey coating may 
appear as localized dull patches or lacework patterns on an otherwise normal 
galvanized coating or may extend over the entire surface. Dull grey coatings 
usually occur on steels with relatively high silicon content which are 
highly reactive to molten zinc.
      Dull grey coating are often thicker than the normal bright or spangled 
coatings and therefore give longer life. It is rarely possible for the 
galvanizer to minimise or control the development of dull grey coatings 
which is dependent basically on steel composition.

      Doug - K1ZO



----- Original Message ----- 
From: <K7LXC at aol.com>
To: <towertalk at contesting.com>
Sent: Wednesday, September 12, 2012 4:13 PM
Subject: [TowerTalk] Brown colored galvanized surface?


> Howdy, TowerTalkians --
>
>    On lots of old galvanized towers sometimes you wind  up with a brownish
> colored surface. Can anyone tell me what it is? It's not rust  but
> something else. Just curious. Tnx.
>
> Cheers,
> Steve     K7LXC
>
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