Long-term monitoring of historic furniture

Re: Jonathan Brown and monitoring at Mount Vernon.  There are
several additional problems with this proposal.

First, there is a need to be exact about what adverse effects are
anticipated before a monitoring system can be developed.  If, for
example, lifting of veneer or changes in the width of cracks are
anticipated, then monitoring has to be designed to catch these
effects.

(2) A monitoring system that records changes after the installation
of a new HVAC system will be meaningless if conditions are not
recorded using the same system through changes of season before the
new system is turned on.  To be statistically meaningful, several
years of changes would have to be recorded.

(3) Changes after installation cannot be proven to be caused by the
new system unless other factors are well controlled, as other
changes could be responsible, including whatever happened to the
objects while the installation was going on.

(4) If by some method, small adverse effects are found, they still
cannot be evaluated without being weighed against beneficial
effects, so these need to be measured as well.

(5) HVAC systems almost never work right when they are first turned
on; adjustments of various kinds always need to be made, and there
is no way to tell if the system works until it has been monitored
through seasonal changes.  So if problems are noted in the furniture
before the system is working properly, this is a different issue.

(6) Monitoring of the system and measurement of the actual levels
achieved need to be accurate because the furniture may respond
noticeably at times when the system goes off-line or messes up in
some way, or when it is overwhelmed by the weather or some other
event.

Although there are many potential adverse effects from HVAC in
historic buildings, wooden furniture is the least likely to be
harmed and the most likely to be helped.  (Monitoring of the
building fabric is probably more important.)  A reasonable question
is why the staff fears these particular problems.  Please feel free
to contact me off-line to discuss this further if it would help.

B. Appelbaum

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                  Conservation DistList Instance 12:28
               Distributed: Thursday, September 17, 1998
                       Message Id: cdl-12-28-004
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