Dancing

Does anyone have any information on the likely impact of dancing on
museum collections?

The Events Manager at one of our historic house museums is keen to
allow dancing at the private functions (wedding receptions etc)
which take place at the property.  The room where the dancing would
take place does not contain any historic collections (but is
adjacent to one which does) and the guests would not have access to
the rooms containing collections.  The Curator instinctively feels
that people should not be allowed to have fun at our sites, and has
asked my advice.

My first guess is that the effects of dancing could be compared to a
small earthquake.  Looking at web sites dealing with the effects of
earthquakes (eg
<URL:http://www.eas.slu.edu/Earthquake_Center/mercalli.html>, it appears that even the most
energetic dancing would not exceed Mercalli intensity level III *
characterised as being felt quite noticeably by people indoors,
vibration similar to a passing heavy truck.  This corresponds to a
Richter magnitude of 4.2, pretty small beer as earthquakes go.

In terms of shock and vibration, this level corresponds to a maximum
acceleration of 0.02g and a maximum peak particle velocity of 20mm
s-1, and these relate to measurements on the dance floor itself, not
objects in an adjoining room, where the effects would be expected to
be very much smaller.

So how much vibration can a painting (for example) take?  Stefan
Michalski (see Art in Transit (1991), p 238) tried vibrating a dummy
painting at a maximum acceleration of 1g for 20 days.  When this had
no effect, he tried more vigorous shaking at 2.5g for 6 hours, and
even this caused no perceptible damage.  Only after continuing this
level of vibration for more than 2 days did visible cracks appear in
the paint layer.  It would appear that an acceleration 50 to 100
times smaller than this would have no effect whatever.  (And this is
the acceleration that would be experienced if the painting were
screwed to the dance floor.)

My feeling therefore is that the effects of vibration caused by
dancing can be discounted, since the accelerations caused are
smaller than those caused by earthquakes, which are presumably
accepted as part of daily life by curators in California and Japan,
for example.

Dr Barry Knight
Senior Conservation Scientist
English Heritage
+44 20 7973 3000
Fax: +44 20 7973 3001




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                  Conservation DistList Instance 15:6
                  Distributed: Tuesday, June 26, 2001
                        Message Id: cdl-15-6-010
                                  ***