Works on Paper in the Tropics

In regard to whether a change in atmospheric pressure could break a
glass case, a big differential in atmospheric pressure, say from
29.80 feet to 30.20 feet would produce a pressure of about 0.25 psi
on glass, or over 300 lbs on a 3-ft x 3-ft light.

In considering the force of atmospheric pressure it is helpful to
remember that the average atmospheric pressure at sea level is equal
to the pressure of a stack of steel four feet high.  That's why
vacuum bagging is such an effective way to apply pressure when
bonding or consolidating items.

P. Gallagher
Materials Preservation
Patrick Gallagher

                                  ***
                  Conservation DistList Instance 11:78
                 Distributed: Thursday, March 19, 1998
                       Message Id: cdl-11-78-001
                                  ***