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Subject: Brass time capsule

Brass time capsule

From: W. T. Chase <tchase4921>
Date: Sunday, November 8, 1998
Clint Fountain's brass time capsule raises some interesting
problems.  For desoldering, better tools than the old Ungar
Desoldering iron with a rubber bulb (which only worked sporadically)
are now available.  Ungar has a great- looking desoldering station
for about $500, and cheaper desoldering irons (Weller) or
desoldering suction pumps to be used with an iron are available. See
on the web <URL:http://www.tecratools.com/solder/de-solder.html> or
<URL:http://www.elexp.com/sdr_d100.htm>

But the real problem is the heat.  It sounds as if the brass sheet
may be sweat-soldered together. If it's a simple linear joint, the
approach by William Hall should work fine.  If you decide to
de-solder, the brass will dissipate the heat strongly, and it will
take a considerable amount of heat to get the solder into a liquid
state so that it can be removed.  The heat may affect the contents.
So the first thing to do is to find out what the contents are.

This should be possible either with neutron radiography or with
high-energy conventional radiography.  Use 320 KV or so and about
1mm of lead or 5mm of brass as a filter to eliminate the soft
radiation.  You should be able to image at least the thicker
organics within the box.  Alternatively, it might be that the
baggage-inspecting machines at the airport, turned up high, would be
helpful.  You could also use a borescope in a drilled hole in the
bottom of the box.  Radiography will also tell you about the solder
distribution and thickness, so that you can make a more informed
decision about how to remove it.

Getting into the box still presents a problem.  I'd suggest using a
slitting saw on the bottom of the box.  You should be able to open
it up from the bottom and leave the visual aspect of the object
undisturbed.  Another possible approach would be to remove the brass
plaque (cutting around its edge with a sharp knife beforehand to
make sure that the lacquer doesn't tear) and then make your hole
there.  When the plaque is screwed back on, no one will see the
opening.

Tom Chase
Chase Art Services
4621 Norwood Drive
Chevy Chase, MD 20815

                                  ***
                  Conservation DistList Instance 12:42
                 Distributed: Monday, November 9, 1998
                       Message Id: cdl-12-42-003
                                  ***
Received on Sunday, 8 November, 1998

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