Paper Glossary

Explanation of the technical specifications

Basis weight [g/m²] (ISO 536)
Measurement is made by weighing a paper sample with a known surface area.

Brightness [%] (ISO 2470)
Brightness value indicates the amount of light reflected in a defined range of the visible colour spectrum.

Opacity [%] (ISO 2471)
Opacity is a measurement of light resistance. It is expressed as the ratio of the reflection factor of a single sheet measured on a black backing against the same sheet measured on a white backing consisting of a stack of the paper to be tested.

Colour (L*a*b*)
Colour is determined by the position in a three-dimensional coordinate system in which L* is the paper’s brightness from 0-100%, a* axis is the green/red direction and b* the blue/yellow direction.

Gloss [%]
The paper sample is illuminated at an angle of 75° and the intensity of reflected light is measured at the same angle. Gloss is given as a percentage of the standard calibrated value (corresponding to 100 %).
Gloss is measured using either Lehmann (ISO 8254/1) or Hunter (ISO 8245/1) methods.
Roughness Parker Print Surf [µm] (ISO 8791-4)
To measure roughness, a sample is clamped with a defined contact pressure (0.5, 1 or 2 mPa) between the measuring ring and a base plate. The amount of air that is allowed to pass between the measuring ring and the paper indicates the roughness.
Roughness measured by the Bendtsen method [ml/min] (ISO 8791/2)
A brass ring is used to seal the surface of the paper and air is forced through at a constant pressure of 15 mbar. The escaping airflow is measured in ml/min. The smoother the paper surface, the lower the airflow.

Bulk [cm³/g]
Bulk is the ratio between the thickness and the weight of the paper.