There is consensus both locally and internationally that the measurement of cotton grade i.e., colour, trash and grade, by the traditional subjective classing should be replaced with objective measurements by high volume instrumentation (HVI). There are however, a number of technical and operating issues to overcome before objective measurement of fibre properties is accepted with confidence by the cotton trade.

One measure is to allow the classing sector to be assessed independently via rigorous round-robin trials so that individual classing houses can correct technical and operational shortcomings in their HVI practice. In this way the industry as a whole can work towards a better prediction of Australian classing grade by HVI measurement.

To this end the Cotton Classers Association of Australia (CCAA) has decided to conduct formilised round-robin trials with the results analysed and interpreted by CSIRO Textile and Fibre Technology. The aim of the trials is to identify and remedy any significant differences in colour and trash between classing houses and HVI lines (types).

An initial round-robin trial (Appendix 1) was conducted during August 2004 and involved five classing houses and a research institute. Nineteen HVI lines and 250 samples were tested on the basis of colour only. This trial found significant differences between classing houses rather than between HVI types.

The CCAA decided to conduct a follow up round-robin trial incorporating formal checks on HVI operating software and calibration procedure by anUster technician and with the inclusion of HVI trash measurements.

The results of this trial are reported here.