Quality Parameters - Specialty Papers

The highest quality standards are vital to cooperating with and supplying our customers in the manufacturing and processing industry. For hundreds of years we have been supplying the quality papers that demanding artists have come to expect of us. Our great expertise in the artist paper sector means that we can bring the necessary creativity and quality mindset to the development and production of our specialty papers. We guarantee our customers the maximum in quality and continuity.

• Grammage (g/m²)
  A 100 cm² sample is weighed.
  EN ISO 536.

• Thickness (mm)
  Thickness is determined using a meter (test area = 2 cm²). The surface pressure depends on the type of paper and averages 25 or 50 kPa.
  EN 20534. 
  

• Tensile strength (N/15 mm Breite)
  A 15 mm wide and 100 mm long test strip is subjected to an increasing vertical load. The maximum force at the moment of tearing is the tensile strength. It is determined for the cross and machine direction of the paper.
  EN ISO 1924.

• Bursting strength (N/cm²)
  A sample with a surface area of 10 cm² is stretched over a rubber membrane that is subject to a uniformly increasing load. The pressure is measured at the burst moment.
  ISO 2758.

• Sizing
  Resistance to penetration of a test liquid (ink) according to DIN 53126.
  Ink penetration is measured photoelectrically.
  Method acc. to Brecht-Liebert.

• Cobb Test (water absorption capability, g/m²)
  Test used to determine the amount of water absorbed after 10 mins by the surface of a 100 cm² large test sample under preassigned conditions.
  EN 20535.

• pH value - surface
  The pH value is determined using a surface electrode and 1 ml of distilled water over a fixed time.
  Data sheet V/17/62 (Zellcheming).

• pH value - acqueous extract
  A sample of 5 g is leached for 1 h with 250 ml of boiling distilled water and the pH value in the extract is measured using a glass electrode after cooling down to 20° C.
  DIN 53124.

• Whiteness (%)
  Determination of CIE whiteness viewed under the CIE D65 daylight illuminant.
  ISO 11475.

• Opacity (diffuse reflectance method, %)
  Test to determine light resistance viewed under D65 daylight illuminant and an angle of 10° (outdoor daylight).
  ISO 2471.

• Moisture content (%)
  A sample of 1-2 g is dried at 105° C and the moisture content is the ratio between actual weight and the weight after drying.
  EN 20287.

• Gurley (s)
  Time is recorded for 100 ml of air to pass through the sample at a pressure of 31 mm water column and 1.56 cm² sample area.
  ASTM-D 726.

• Air permeability (L/m² s)
  Determination of apparent porosity with a pressure differential of 2 mbar and a test area of 20 cm².
  DIN 53887.

• Herzberg flow rate tester (s)
  Test to determine flow rate using 100 ml prefiltered distilled water (20° C) applied to the test filter (effective area 10cm²) at a constant hydrostatic head (10 cm).

• Klemm capillary test (mm)
  Determination of capillary rise by measuring the wet part of a paper strip (15 x 250 mm) immersed in prefiltered water (20° C).
  DIN ISO 8787.

• Resins and oils (mg/100 g)
  Determination of dichloromethane soluble matter.
  ISO 624.

• Wet tensile (mm, water column)
  Determined by continuously increasing a water column over a test area of 14.5 cm² until the paper bursts.
  Plant standard.

• Water absorption (g/m²)
  Determination using weight differential of a test sample with 100 cm² area. (Weight 2 - weight 1) x 100 = water absorption. Weight 1 = weight in dry state. Weight 2 = weight after immersing the test sample in distilled water for 1 min and removing the excess surface water.
  Plant standard.

• Bekk smoothness test (s)
  Air is drawn across the paper surface under reduced pressure and a test value is reported as time in seconds for a given air flow.
  DIN 53107.

• Gloss (%)
  Determination of reflected light of semi-gloss coated paper at a 60° incident angle. EN ISO 2813.

• Silica (%)
  DIN 54377-2.

• Iron (mg/100 g)
  DIN 54374.

• Copper (mg/100 g)
  DIN 54375.

Further quality criteria can be determined and confirmed by an external, accredited test laboratory. We issue a Certificate of Analysis (CoA) if required.