Grammage Standard
International metrology specifies the precise gravimetric procedure for determining the mass per unit area of paper, paperboard and corrugated board components. Quality laboratories implement iso 536 to verify that delivered substrate grammage matches contractual specifications within strict commercial tolerances. The method requires conditioning test specimens in standard atmospheric environments before cutting exact geometric areas and weighing them on calibrated analytical balances.
Procurement contracts use these mass determinations to calculate square meter yields and invoice pricing. The standard covers mass per unit area measurement exclusively, excluding moisture determination protocols and surface density profiling from its direct scope.
Gravimetric Procedure
Specimen preparation begins by conditioning cut sheets in controlled atmospheres of twenty three degrees Celsius and fifty percent relative humidity. Executing iso 536 involves cutting multiple square or circular samples using high precision punch cutters to guarantee accurate surface boundaries. Analytical balances record sample weights to within one milligram precision.
Dividing the recorded mass by the exact specimen surface area yields grammage expressed in grams per square meter. Averages across multiple cross web samples eliminate local basis weight variations caused by headbox flow deviations.
Production Tolerances
High speed converting equipment requires consistent substrate grammage to maintain uniform creasing depth, folder gluer transport speed and adhesive absorption. Substrates verified under iso 536 allow carton manufacturers to detect basis weight drift before starting large print campaigns. Solid bleached sulfate boards, coated recycled boards and fluting mediums require tight grammage windows to prevent die cutting wear and scoring cracks.
Invoicing disputes resolve directly through these standardized mass measurements. Consistent grammage guarantees predictable performance across industrial packaging conversion lines.
