INTRODUCTION

This Standard was prepared by the Joint Standards Australia / Standards New Zealand Committee TX/12, Wool.

This series of test methods sets out the procedures required to measure mean fibre diameter of wool samples. Methods 1 and 2 give procedures for the preparation of samples. Methods 3 to 5 set out mean fibre measurement procedures by three different methods.

The objective of these Standards, when measuring mean fibre diameter, is purely to rank animals within management groups for the purposes of animal selection. It is not to provide measurements for the sale or trading of animals, nor is it appropriate to make comparison of animals between management groups, as environmental conditions will differentially affect fleece parameters of individual animals. Legitimate comparisons are only possible when animals are run together, in the same management group, for the full period of fleece growth.

For fleece testing, several methods of measurement of mean fibre diameter are applicable. These are the Airflow Method, and methods using Sonic A, SIROLAN-LASERSCAN, and OFDA measuring systems.

Determination of mean fibre diameter for fibre trading by Sonic A method is no longer accepted internationally. It may, however, be used to rank animals on the basis of mean fibre diameter for animal selection purposes.

These test methods cover the fineness measurement of cleaned, midside samples of greasy wool. Test specimens are prepared in a way which is appropriate for each test method. Detailed descriptions of the instruments, including their calibration, are to be found in AS/NZS 1133 (Airflow Method), IWTO(E)-7-73 (Sonic Method), IWTO-12-95 (SIROLANLASERSCAN Method) and IWTO-47-95 (OFDA Method).

Since the physical principles involved in the various measurement techniques are different, exact correspondence of results between the methods will not necessarily exist for one sample of wool. Consequently, the precision values which are indicated for each instrument relate only to that method, and do not include any variability which may exist between methods. Equally, comparisons between diameter results may not be reliable unless the results have all been derived from the same measurement system.

The measurements should be regarded as relative, not absolute values, and they should only be used for within-flock comparisons.

Because smaller laboratories may not have the apparatus required to comply with the conditioning requirements in IWTO-52-96 or AS 2001.1, alternative means of producing and maintaining a constant laboratory atmosphere are allowed in this series of Standards.

There are a number of mathematical calculations reported as additional information and sometimes used as indices, in some individual animal selection programs or other purposes. Few of these indices, such as Spinning Fineness, Coarse Edge, Comfort Factor or Prickle Factor have been researched to demonstrate their applicability in breeding programs and to illustrate textile processing or product consequences.

Those contemplating their use should determine the technical relevance, accuracy and precision levels of such data before considering them for ranking animals for selection purposes.