Standard Laboratory Test Methods for Paperboard Physical Property Verification
Paperboard physical property verification requires strict ISO 187 conditioning and standardized test methods to ensure compliance and prevent customs holds.
Conditioning Equilibrium
Moisture Balance
Atmospheric stabilization represents the state where a paperboard sample neither gains nor loses moisture to the surrounding air under controlled humidity and temperature. Standard testing climates require a conditioning equilibrium to be reached before physical properties like stiffness or tear resistance are measured. This state is defined by successive weight measurements showing no change over a specified period.
Testing Protocol
Sample preparation occurs in a room kept at twenty-three degrees Celsius and fifty percent relative humidity. A pre-conditioning step at low humidity is used to ensure the conditioning equilibrium is approached from dry conditions. Paperboard holds different amounts of moisture depending on whether it starts wet or dry because of hysteresis.
This divergence affects mechanical test results.
Process Tolerance
Inaccurate calibration of testing chambers or insufficient exposure times lead to variable measurement results. Physical properties fluctuate when samples fail to reach conditioning equilibrium before undergoing mechanical analysis. Strength testing of corrugated boards requires several hours of exposure, whereas light papers stabilize in less than one hour.
The rate of stabilization depends on the grammar and thickness of the board. Insufficient conditioning compromises the reproducibility of performance data across different laboratories. This protocol is strictly followed in certified paper testing facilities to ensure legal compliance.