Grammage

Measurement Methodology

Laboratory determinations follow international standards requiring conditioning at twenty-three degrees Celsius and fifty percent relative humidity to achieve hygroscopic equilibrium. Precision punches cut test specimens to exact dimensions, typically one hundred square centimetres or five hundred square centimetres, to eliminate edge burrs and dimension errors. A calibrated analytical balance measures the specimen mass to a resolution of one milligram, with the result multiplied mathematically to calculate the mass of a single square metre.

Variations in relative humidity alter measured results because cellulosic fibres absorb or desorb ambient water molecules, shifting total sheet weight by several percentage points. On-line paper machines measure the metric continuously across the moving web using beta radiation attenuation gauges or infrared absorption sensors, enabling immediate adjustments to stock delivery at the headbox.

Commercial Boundary

Purchase orders for packaging substrates specify this property with an accepted commercial tolerance window of plus or minus five percent from the target nominal value. Inconsistent area mass disrupts gravimetric filling lines and causes registration errors during sheet-fed offset lithography or gravure printing. Grammage directly dictates raw material yields during web converting, as high values reduce total linear metres obtained from a reel of fixed weight.

Structural strength specifications such as bursting resistance and tensile energy absorption correlate closely with sheet mass within a given fibre furnish. Papermakers optimise this metric to provide required physical stiffness while using the minimum fibrous mass necessary to satisfy structural packaging constraints.