AB Lorentzen Wettre Fiber Tester

L&W Fiber Tester

Measures pulp fibre quality quickly and easily

L&W Fiber Tester measures fibre quality quickly and easily and is at the same time an instrument for advanced analysis of fibre dimensions. The measurement technology is automated, which enables frequent analysis of pulp quality. The instrument is intended and optimized for laboratories and has a compact design, which makes it easy to place.

L&W Fiber Tester measures fibre length, width, fines, shape factor and coarseness. Software modules for vessel cells, local deformations (kink) and calculations of fibre mixes.


The instrument has a sample feeder with six positions designed as a rotating disc. This automates the measurement procedure, making it easier for the operator.

The total measurement cycle is made within six minutes. One feature is that images of fibres are displayed during measurements. It is also possible to save images for later viewing.

Easy to place

L&W Fiber Tester is a bench-top model, making it easy to fit in any laboratory. The reports and statistics are flexible. For example, it is easy to select different weighing functions for averages and distributions of fibre properties. The report is also easy to customise.

Measurement with two-dimensional imaging technology

The principle with two plates allows the fibres to move freely in two dimensions but not in the third. This is not the case in a capillary tube, which orients the fibres only in one dimension. A very small measurement gap between the plates secures a good alignment of the fibres. The whole fibre can then be seen by the camera.

L&W Fiber Tester measures several different fibre properties:

Length – Fibre length influences sheet strength but can also have a negative effect on sheet formation. L&W Fiber Tester has been designed to measure fibre length with minimum impact from the degree of deformation.

Width – Thinner fibres provide a better and more even formation of the sheet.

Shape factor – A variation in shape factor between 81 and 85 percent can make a difference of 15 units of tensile strength in unrefined samples. This difference remains subsequent to refining with constant energy even if tensile strength has increased due to fibrillation of the fibre surface.

Fines – Fines have a negative effect on dewatering and pressing. Fines generated in beating are good for strength. All objects shorter than 0.2 mm are defined as Fines. Fines content (objects below 0.2 mm) is expressed as percentage of amount of fibres (objects above 0.2 mm). A length to width ratio of 4 can be set on all detected objects as a condition to be regarded as a fibre/fines object and is often used.

Coarseness – Coarseness is defined as weight per fibre length unit and is often related to fibre wall thickness and flexibility.

Extra software is available for the analysis of kink, vessel cells and fibre blends. Refer to separate descriptions of these programs in this section.

  • Fast classification of pulp quality
  • Early detection of deviations in pulp quality
  • New properties to define pulp quality
  • Compact design
  • Sample feeder
  • Proven measurement methodology
  • Self cleaning measurement cell
L&W Fiber Tester – Code 912
L&W Fiber Tester software, PC, power supply



Length from 0.2–7.5 mm
Width 10–100 µm
Shape factor 50–100 %
Fines (< 0.2 mm) as % of fibres > 0.2 mm, limit is optional
Coarseness - Weight per fibre length

Table/bar chart with 2-15 length intervals and easily adjusted limits, including an option to include or exclude fines

Length distribution in 75 classes
Width distribution in 50 classes
Shape factor distribution in 50 classes

Surface data

Proportion of length in two-dimensional length/width matrixes, 15×15 classes
Shape factor in two-dimensional length/width matrixes, 15×15 classes

Raw data
Length, width and shape factor
Network, USB

Installation requirements
100 W
Instrument air
0.4–0.6 MPa (60–90 psi)

Dry, oil free


100 l/h
0.3–0.6 MPa (45–90 psi)
30–40 °C
10 µm



L&W Fiber Tester Blend
L&W Fiber Tester Kink/Vessel



0.4 × 0.5 × 0.6 m
16 × 20 × 24 in


0.2 m³
7 ft³

Net weight

35 kg
77 lb

Gross weight

65 kg
143 lb


Applicable standards
ISO 16065-2


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