AB Lorentzen & Wettre PPS Roughness Tester

L&W PPS Tester

Accurate measuring of surface roughness using the PPS method

L&W PPS Tester is used to measure the surface roughness of coated and calendered printing and writing paper. The method is also used for measuring the surface roughness of newsprint. The instrument uses the rate of leakage of air between the paper surface and a smooth reference plane to sense the roughness. The results give a good overview of printability.

Measuring starts automatically as soon as the sample is placed under the measuring head. The sample is held against the measuring head with the chosen clamping pressure and measurements are taken during the chosen measuring period. It is then released and can be measured in a new position. Everything takes place in one simple measuring sequence.


Measuring compressibility

The compressibility of the paper sample is determined by measuring its surface roughness at two predetermined clamping pressures, thereby simulating the effects of linear loads in various printing methods. Compressibility is reported as a percentage reduction of surface roughness or as a ratio of the two surface roughness measurements.

Function check

It is essential to be able to easily ensure that the instrument is correctly adjusted. Important parameters such as air tightness, zero airflow and clamping pressure can therefore easily be checked by means of a fixed check sequence, after which a report containing set points and deviations from them is generated.

Traceability and reproducibility

Reproducibility is important for all measuring methods. Each L&W PPS Tester is individually calibrated and traceable to Lorentzen & Wettre’s master instrument. This ensures that every L&W PPS Tester and measuring head measures identically within set tolerances. Lorentzen & Wettre uses a master system equipped with six measuring heads that are regularly checked against each other.

L&W PPS Master Kit

L&W PPS Master Kit enables the regular routine checking of all the PPS instruments used by a mill, thereby ensuring that all measurements are fully comparable and reproducible. L&W PPS Master Kit is traceable to Lorentzen & Wettre’s own master system for PPS measuring, thereby guaranteeing reproducibility. The instrument is supplied together with a 1-year subscription which consists of four sets of reference paper samples.

  • Rapid and accurate measuring
  • Easy to operate
  • Traceable calibration
  • Fast check of main functions
  • Built-in printer
  • L&W PPS Master Kit included

L&W PPS Tester – Code 165
Inspection kit comprising three nozzles, a plug and an adaptor. Backing holder with soft and hard backing. Spare discs with soft and hard backing. Air nozzle with hose and adaptor. L&W PPS Master Kit. Zerocheck film for inspection of PPS head at very low values. PC software for setup and calibration (software available only in English). Cable for connection to an external PC. Printer rolls


0.60–6.00 µm


Display and printer
5 digits, up to 3 significant digits reported
Delay time
Selectable 4–10 s
Clamping pressure
0.5, 1.0 or 2.0 MPa
Test air pressure
19.6 kPa


Measurement values
- PPS Roughness and compressibility
- Individual values
- mean value
- standard deviation
- coefficient of variation
- maximum and minimum values of the series



- connectable to L&W Autoline Data Acquisition Workstation


Installation requirements

75 W
Instrument air
>0.5 MPa (75 psi)
Air consumption
0.5 m³/h (19 ft³/h) NTP



0.3 × 0.4 × 0.4 m
12 × 16 × 16 in


0.25 m³
9.3 ft³

Net weight

21 kg
46 lb

Gross weight

34 kg
75 lb


Applicable standards
BS 6563, ISO 8791-4, TAPPI T 555, (SCAN P 76 withdrawn)  


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