A model to explain anomalous moisture sorption in wood under step function driving forces

It has been hypothesized that "anomalous" transient moisture sorption in wood at high relative humidities is due to slow sorption of moisture in the cell walls. A mathematical model describing this phenomenon has been developed, which fits well the two-stage sorption (Fickian and non-Fickian) visible in experimental data and uses parameters with clear physical meaning. The values of these parameters can be derived by simple means. Thickness effects and other non-Fickian behavior are examined.