Chris

Your record of your wandering was great.  Maybe we could all do something
like that from time to time to give members of the list a feeling for the
various places we live in.  I will post separately on your question about
glass walls held up by steel tracery.

My week has been fraught with submissions and proposals for new projects.  In
between I found time to dangle on the ropes on the outside of a couple of
1930s department stores.  Both have self-supporting sandstone veneer cladding
over a steel and concrete structure.  The first has timber windows, the
second however has some of the first anodised aluminium windows installed in
a building of its type ... so I am too am chasing ideas on cleaning and
protecting this wonderful material of the twentieth century.

][<en's advice is becoming standard fare - we were involved with a mid 1950s
curtain wall where the entire curtain wall was cleaned in that basic manner
... but the issue which doesn't yet seem to be well understood is how we can
keep the aluminium in reasonable condition in the future.  Cleaning the
window frames as well as the glass in the windows during regular window
cleaning activities is part of the equation for sure.  I know that DOCOMOMO
ran a conference on preserving curtain walls, and will pursue this as a
source.  Also, there is a book edited by Thomas Jester on 20th Century
building materials ... don't know whether this has any ideas or suggestions.

Back to the department stores.  Both were in pretty good nick - the main
problems were eroding pointing on one, and the lack of cleaning of the
windows leading to deterioration.  And the ubiquitous draining of water from
flat surfaces down the face of the building, with resultant black staining
(algal growth).  I wish architects of the time hadn't experimented so much
with materials (but are they any different now?).

As for conserving 20th century materials that are still around ... well, sort
of.  The aluminium curtain walls will be a nightmare, because the finish
technologies have changed so much.  And as for the glass ... what once was
simple, is now horrendously difficult.  I dread to think how difficult it
will be working out just what sort of low-e coating and interlayer is present
in a laminated insulating glass unit when all the construction documents have
been lost in forty years time.  And even if you find out, the cost of
maintaining the technology to produce these coatings will be such that
matching it will be impossible.  The only way will be to work with the
existing technology of that time to come up with a suitable visual match!
Hardly truth to materials and minimal intervention.  So look out those of you
who are just graduating now ... by the time you are ending your career, you
will be dealing with the 80s and 90s behemoths ... and struggling with the
complexity and difficulties which will present!

Enough of this stream of consciousness.

Cheers

david