Cathodic protection doesn't work in the air because there is no medium to
allow the battery to activate allowing the free electrons to travel.
Seawater is an ideal environment for supporting this protective action.  It
does work underground and is a method used to reduce corrosion of submerged
storage tanks.

Mark
-----Original Message-----
From: JRhodes <[log in to unmask]>
To: [log in to unmask]
<[log in to unmask]>
Date: Monday, September 13, 1999 10:22 AM
Subject: Re: anchors and anodes


>Re: preservation of a large magnificent early anchor of the industrial
>revolution.
>
>The old nautical solution, that works on the briny deep, is to fix
>sacrificial anodes of zinc.  I don't know why this shouldn't work on land.
>At the US Naval Academy, they've scraped their old anchors down to firm,
>undelaminated metal, primed and painted...no anodes.
>
>Speaking of anodes, I attended an interesting lecture by a London architect
>who described drilling and inserting cathodic protection to individual
>failing terracotta cramps in a building facade, avoiding damaging
>disassembly.  The wall is "radared" and a thin drill probed thru mortar
>joints to touch the endangered iron cramp where a wire is inserted to a
>sacrificial element in a tube at the mortar surface.  He swears it works.
>
>I've heard of such measures attached to cars and steel frames, like out in
>Salt Lake City...any experience, papers or documentation out there for
>preservationists?
>
>--Jim