Sorption Isotherm

Hysteresis Effect

Moisture absorption by flax fibers occurs along a curved path that depends on the direction of the humidity change. This curve, called the sorption isotherm, exhibits hysteresis, meaning that a fiber holds more moisture at a given relative humidity when it is drying out than when it is wetting up. The molecular structure of flax, consisting of crystalline cellulose and amorphous polymers, creates this difference in moisture retention.

Recognizing this behavior helps mills predict fiber weight changes during international shipping.

Manufacturing Control

Conditioning rooms utilize these moisture curves to set the optimal relative humidity for yarn storage prior to weaving. Storing yarn at the correct moisture levels prevents yarn breakages and improves processing efficiency on high-speed loom frames. Quality testing stations must operate at a fixed relative humidity of sixty-five percent to ensure repeatable test outcomes.