Architectural drawings

Cecilia Vietto <cvietto [at] agatha__unr__edu__ar> writes

>... The biggest
>problem that we have is to relax the drawings and flattening them.
them."

The Micro Climate Generator has been used to successfully relax and
flatten very delicate rolled paper documents in a special chamber at
the Ontario Archives in Toronto for some years now.

As I understand it, the procedure generally used is as follows: The
chamber is initially set for a humidity of about 50%, regardless of
the initial moisture level of the rolled document. The document is
left in the chamber at least overnight. The humidity level is then
ramped up by 10%, and the chamber is maintained at the new level of
humidity to allow the document to stabilize. After a few hours, the
chamber is ramped up by another 10%. This is repeated until the
chamber is at 80% humidity. After the document has stabilized at the
final humidity, it is placed between felts and under weights.

This chamber was custom-built specifically for this purpose some
years ago. The original humidity control mechanism had a tendency to
"spike" (as do most humidity control systems). A Micro Climate
Generator (MCG) was used to replace the built-in system in 1992, and
has been used extensively since then. The MCG uses a patented system
to provide extremely even supply of temperature-sensitive humidity
controlled air for display and research.

Caution: It has been noted that transparent paper may be prone to
dimensional changes when humidified, so this flattening method may
not be indicated for this project.

More information on the Micro Climate Generators may be found on our
web site: <URL:http://www.keepsafe.ca> or by calling me on our toll
free line.

Jerry Shiner
Keepsafe Systems
Supplies and Solutions for Microclimate and Oxygen-free storage
toll-free phone: 800-683-4696
Object and Textile Conservation Services Ltd.



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                  Conservation DistList Instance 15:57
                 Distributed: Friday, February 15, 2002
                       Message Id: cdl-15-57-006
                                  ***