Preparing materials for freeze-drying

Reni Teygeler <rene.teygeler [at] wxs__nl> writes

> ... Does anyone have any experience in packaging before
>deep-freezing for preservation purposes, or does anyone have any
>suggestions?

The main reason for packing wet books with plastics prior to
freezing is to be able to separate the books from each other when
they are put into the freeze- dryer. If they are put in sealed
plastic bags all the moisture will remain there until the plastic
bag is removed. If, on the other hand, plastic sheets are put only
between the books, moisture will escape from edges and all other
exposed areas. This has the advantage that the books start drying
already in the storage freezer, and not only in the freeze dryer. If
there are loose parts that are in risk of becoming detached during
handling, these items can be banded with a strip of stretch-plastic
that only will hold them together without covering more than
necessary of the book or sheaf of archival material. (We use the 100
mm wide "Andywrap film" for this and other purposes. It is for
example ideal for re-attaching cloth or leather spines in normal
conservation work)

If you would have the rare opportunity of being able to prepare
individual wet books prior to freezing, the following method gives
good results. Interleave the book with plastic in sections of ca.
5-7 mm, press the book flat and deep freeze it in this position.
Remove the plastic before moving it to the freeze-dryer and it will
dry quicker and in a slightly more flat state than without the
interleaving. Needless to say--the method is time consuming and the
risk for tearing of the paper is high, but it can give nice results.

During freeze-drying it is optional if the items are checked
regularly and moved around to allow for maximum exposure of the wet
areas. In vacuum freeze-drying this may not be of the same
importance.

Per Cullhed
Head of Conservation
Uppsala University Library
Sweden


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                  Conservation DistList Instance 16:11
                  Distributed: Friday, August 2, 2002
                       Message Id: cdl-16-11-004
                                  ***