Testing statistics 2015/2016
Summary of wool testing statistics for 2015/2016
 


Mean Fibre Diameter is one of the most important parameters of wool. It determines what end product can be made from the wool. The handle and visual appearance of the overall product is affected by the fineness of the wool. Price differentials exist for different mean fibre diameter ranges. Mean

Fibre Diameter is expressed in micrometres (one millionth of a metre). Currently there are five test methods for the measurement of fibre diameter which are recognised by IWTO.

These are IWTO-6 (Combed Sliver on Airflow) and IWTO-28 (Airflow method), IWTO-12 (Laserscan method), IWTO-47 (OFDA method) and IWTO-8 (Projection Microscope).


MEAN Fibre Diametre

Mean Fibre Diameter is one of the most important parameters of wool. It determines what end product can be made from the wool. The handle and visual appearances of the overall product is affected by the fineness of the wool. Price differentials exist for different mean fibre diameter ranges. Mean Fibre Diameter is expressed in micro meters (one million of a meter).

Currently there are five methods for the measurements of fibre diameter- which are recognized by IWTO. These are IWTO-6 (Combed Silver on Airflow) and IWTO-28 (airflow method), IWTO-12 (Laser scan method) IWTO-47 (OFDA method) and IWTO-8 (Project Microscope)

AIRFLOW METHOD

This is the traditional method for mean fibre diameter measurement. It is quick, simple and accurate on most types of wool.

Approximately 10g is removed from each sub sample and combined into one sample. A Shirley Analyzer is used to process the sample. This removes any VM, the remaining dirt and effectively cards the sample, untangling the fibre to produce an open web. The sample is conditioned to the point of equilibrium in a standard atmosphere of 20 degrees and 65% RH.

Two specimen of 2,5g are weighed and measured in duplicate on 2 Airflow instruments using the principle of constant air pressure to fixed mass of wool in a standard volume chamber to determine the air flow through the specimen.


LASERSCAN

Approximately 10g is removed from each subsample and combined into one sample. The sample is conditioned to a point of equilibrium in standards at 20 degrees and 65% relative humidity.

Fibre snippets are taken from a sample by a mini –coring device and places in the Laserscan. The diameter of the fibre snippets, suspended in an liquid solution, are measured as they pass through a laser beam.

At least four measurements are performed per test.


Optical Fibre Diameter Analyser (OFDA)

The OFDA is essentially an automatic microscope set above a moving clean glass slide containing fibre snippets. The instruments magnifies and captures images of the individual fibres using a video camera, whereafter it then identifies and measures each fibre.

Approximately 10g is removed from each subsample and combined into one sample. The sample is conditioned to a point of equilibrium in a standard at 20 degrees and 65% relative humidity.

The sample is minicored and the snippets fall directly onto the glass slide. The slide is placed on the stage of the OFDA and the snippets are measured . At least four measurements are performed per test.