Technical Requirements

Weight in grams of one square metre of paper or board. Measured in accordance with ISO 530 standard, tolerance of +/- 5%

Thickness of a sheet of paper or paperboard, measured under certain specifically stated conditions, usually measured in millionths of a metre (microns or μm). Measured in accordance with ISO 534 standard, tolerance: +/- 7.5%.

Bendtsen is a commonly performed test to determine the roughness / smoothness of paper and paper board products by a constant pressure air-flow method. The rate at which air passes through the sheet is expressed in millilitres per minute. Measured to ISO 2494 standard.

Compactness property of a sheet in relation to its weight (whose value decreases as compactness increases). Bulk is calculated as caliper divided by grammage. Bulk density is expressed as grams per millilitre g/mL

Resistance of paper to rupture when pressure is applied to a side by a specified instrument. Bursting strength is usually quoted in kPa (kilopascal). Measured to ISO 2758 standard.

Resistance of a paper sheet to tearing, usually measured by the force required to tear a strip under standardised conditions. It is an important basic physical property of paper and paperboard. It is measured in both machine direction (MD) & cross direction (CD) and expressed as mN (mili Newton). Measured to ISO 1974 standard.

The ability of paper or paperboard to withstand bending or crushing forces. Stiffness is particularly important when determining the correct grade of paperboard for packaging applications. Stiffness also relates to other strength properties such as toughness, creasability and foldability. It is measured in both machine direction (MD) & cross direction (CD) and expressed as mN (mili Newton). Measured to ISO 5628 standard.

Resistant property of a sheet to pull or stress produced by tension. Expressed as the force per unit width of a sample that is tested to the point of rupture. It is measured in both machine direction (MD) & cross direction (CD) and expressed as mN (mili Newton). Measured to ISO 1924-2 standard.

The Dennison Wax Pick test is for the evaluation of surface strength of paper. Waxes are heated and applied to the surface of the sheet. After cooling, they are pulled from the surface and the wax stick is checked to see if it has pulled fibre from the surface. The highest value wax which does not rupture the surface is reported as the pick strength of the sheet.

A test method for determining the water absorptiveness of sized paper and board measured under ISO 535 standard conditions. This identifies the quantity of water that can be absorbed by the surface of paper or board in a given time. A test piece is weighed immediately before and immediately after exposure for a specified time. The result of the increase in mass is expressed in grams per square metre (g/m2).

Percent of water by its weight in paper or paperboard. This can vary according to atmospheric conditions because of the ability of the material to absorb or emit moisture. The ISO 287 test method specifies a method for determining the moisture content.

Moisture content gets measured as relative humidity (RH), and most papers are designed to be stable at 45-55% RH. Typically, manufacturers produce paper to an absolute moisture content making up a percentage of the paper’s total weight.

Test for white papers. Internationally Whiteness is the most commonly used measure as defined by the CIE (Commission Internationale de l’Eclairage – International Commission on Illumination). The CIE measure of whiteness is a measurement of the light reflected by the paper across the visible (daylight) spectrum. Measured under D65-100 daylight conditions.

Brightness test for white papers, as defined by the TAPPI (Technical Association of the Pulp and Paper Industry) is the measurement of the amount of reflectance of blue light.

The Blue Wool Scale measures and calibrates the permanence of colour. Traditionally this test was developed for the textiles industry but it has now been adopted by the paper and printing industries. A rating between 0 and 8 is awarded. For example, a Blue Wool 6 rating, is the minimum lightfastness required to meet international standards set by The Fine Art Trade Guild for limited edition prints.

Rub, abrasion, and scuff resistance describes the ability of paper or board to withstand marking or colour transfer during hand­ling in conversion and use. The Crockmeter is used to assess colour transfer in testing against ASTM F1319 and ISO 105-X12.