To characterize humidity conditioning ceramics, the relative humidity as a
function of temperature (H(T)) was measured using a glass desiccator techni
que with varying the ambient temperature between 298 and 288 K, A logarithm
ic plot of H(T) was approximately represented by a linear function, and the
humidity conditioning ability was evaluated by the slope (B) of such a lin
ear equation (B-value method), Humidity conditioning ceramics, made of seve
ral ceramic materials such as Wakkanai diatomaceous shale, calcium silicate
and zeolite, were characterized according to their B-values in comparison
with wood, The relation between the B-value and the ratio of the exposed su
rface area of the material to the volume of desiccator was also investigate
d to extend the efficiency of the B-value method to the large scale of actu
al applications, It was also found that the B-value method to estimate the
humidity conditioning ability for wooden material can be applied to porous
ceramics, which had B-values higher than wood, The porous diatomaceous cera
mics showed the highest B-value among the ceramic investigates.