Standard Protocol
Establishment of uniform environmental parameters for testing paper and paperboard requires precise regulation of temperature and relative humidity. Adherence to board conditioning iso 187 ensures that cell wall moisture levels are brought to a stable, reproducible state before physical evaluation commences. This international standard specifies a temperature of twenty-three degrees Celsius and fifty percent relative humidity as the baseline condition for testing.
Equilibrium Mechanism
Absorption and desorption of water molecules by cellulose fibres occur continuously until the partial pressure of water vapour in the sheet matches the surrounding atmosphere. The process of board conditioning iso 187 follows a hysteretic curve where pre-drying at a lower humidity ensures that the final equilibrium is reached from the dry side. This approach minimizes variations caused by the direction of moisture adsorption, ensuring consistent mechanical properties across different production batches.
In multi-ply cartonboards, unequal moisture migration across the plies can induce warping, which interferes with high-speed sheet feeding.
Performance Impact
Mechanical properties such as tensile strength and bursting strength are highly sensitive to the moisture content of the fibrous matrix. Undergoing board conditioning iso 187 prevents erroneous measurements during high-speed converting or folding operations. Accurate moisture levels stabilize the stiffness of the sheet, allowing converters to predict runnability and scoring behaviour.
