Proceedings e report - Firenze University Press

WOOD SCIENCE FOR CONSERVATION OF CULTURAL HERITAGE
Fig. 3 – The average dimensional change isotherms for the adsorption and desorption of water vapour at 20 o C.
A convenient way of expressing swelling and shrinkage behaviour of individual wood species is to
plot dimensional change as a function of EMC. By way of example, such relationship is shown in
Fig.4 for the tangential and radial directions in the lime wood.
All the experimental points for the EMC values between 0 and 25% were obtained by adsorption and
desorption of water vapour at varying RH whereas the last point corresponds to a wooden specimen
fully saturated under distilled water. Generally, the measurements did not show any differences
between the dimensional change values at the same EMC but obtained after adsorption or desorption.
In this way, the so-called secondary effects of moisture sorption on dimensional changes [6] proved
insignificant at least for any practical purposes.
.
Fig. 4 – Dimensional change of lime wood in the radial and tangential directions plotted as a function of the
equilibrium moisture content.
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