I know someone wrote a thesis on cathodic protection a couple of years ago
at the University of Pennsylvania, although his case study was a Frank Lloyd
Wright concrete block house in California (no marble/limestone/sandstone to
be found).  I forget the details, but if you like I may be able to scrounge
the author's card up so that you can contact him.
- Johnette

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From: JRhodes <[log in to unmask]>
To: [log in to unmask]
Subject: Cathodic protection
Date: Thu, 27 Jan 2000 18:23:43 -0500

Greetings Heads:

I am collecting data and case applications of cathodic protection of
buried ferrous metals in historic facades in order to better
understand the practicality of non-destructive insertion of
sacrificial anodes in stone clad structures...both marble and
limestone/sandstone facades.  I have Martin Weaver's excellent
writing on the subject, including power impressed protection systems,
but I'm also looking toward recent case histories, detection,
monitoring and sourcing materials.  I met an Englishman who has
applied the system to architectural terracotta, wiring small anodes
set within joints between elements.  No corrosion, no activity, no
problem.  Sacrificial corrosion...problem...fix the problem and/or
replace the anode.

Seems like a relatively low-tech, relatively non-invasive way of
inhibiting corrosion of stone cramps short of coring, cutting,
removal, replacements and loss of masonry.  Question is when, where
and how to apply the technique.

Ideas and experience out there?

The (not always right) Reverend