Encapsulation

>I was taught in encapsulating that you leave small holes in the tape at
>the corners of the mylar-d to permit you to squeeze out the air and also
>to permit breathing of the paper.  To seal it totally, I was taught,
>would create an environment for mold growth from the moisture content of
>the paper.   I have now heard of some conservators who believe you seal
>it entirely.

Boy, two "most-misunderstood concepts" in one mailing.  Library of
Congress research reported by Chandru Shahani some years ago and
published in Abbey Newsletter and the NJ state preservation newsletter
found that if you encapsulate potentially or already acidic paper (that
is, unwashed and/or unalkalized paper) you increase the speed of
deterioration 8-10x.  [On the basis of much more recent research that I
can't cite immediately, this is probably due to the build-up of
by-products of deteriorating paper retained within the capsule.]  It
does not help to leave gaps at edges or corners.  *However*, if you
encapsulate with a backing sheet of buffered paper (e.g. paper that
meets the Z39.48-1984 (soon to be -1992), you can reduce the speed of
acidification to what it would have been without encapsulation.  Please
contact me directly (508-470-1010 or NEDCC [at] world__std__com) if you want a
reprint or citation.

Karen Motylewski

                                  ***
                  Conservation DistList Instance 6:49
                  Distributed: Friday, March 12, 1993
                        Message Id: cdl-6-49-008
                                  ***