Deterioration within enclosures

I agree with Karen Motylewski's comments that the more extreme
deterioration found at the gaps in wooden slat backings could be related
to moisture.  However, it seems to me that the average moisture content
of the sheet would be the same and that the relevant differences in the
exposed area might be that (1) higher moisture levels would occur here
temporarily  and (2) the more rapid changes in moisture levels would
cause some mechanical stress.  On the first point, perhaps at higher
humidities the rate of deterioration is much, much greater, that is, the
relationship between damage and increased relative humidity is not
linear.  (Any scientists listening?)  On the second point, perhaps the
mechanical stress allows chemical deterioration to occur more rapidly.
It certainly is a system with many variables.  It does show that there
is more at work here than trapped acid gases.  If they were the only
culprit, then the damage would be more severe in the area away from the
opening.

Dan Clement
Ithaca, NY

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                  Conservation DistList Instance 6:53
                 Distributed: Saturday, April 10, 1993
                        Message Id: cdl-6-53-004
                                  ***