Dark Fibre Risk and Prediction
This paper has been reproduced from the original source document using Optical Character Recognition software to convert printed text into electronic format. The source documents are no longer in print. The papers cover work into dark fibre measurement and risk assessment conducted by CSIRO's Textile and Fibre Technology Division , when it was located at Ryde, NSW. It has been necessary to reformat the document and hence the page numbering and layout is no longer identical to the original, but the text is identical, except where obvious errors have been corrected.
Abstract
Australian wool has the reputation of being relatively free of dark fibre. However, dark fibre contamination is still a contentious issue within the wool industry. Research has enabled us to develop an instrument and a technique to determine the dark fibre contamination content of wool top. This examination point, however, may be too late for topmakers who have made commitments for light coloured end use of their product.
The provision of a measurement of dark fibre content that can be used as a basis for the trading of greasy wool is not practicable. The major impediment is that only a minute amount of urine stained or pigmented wool in a consignment is sufficient to exceed the topmakers' limit.
Our research has shown that the major source of dark fibre contamination in Australian merino wools is from urine stained fibres with pigmented fibres being of secondary importance. On this basis we have devised a Dark Fibre Risk Scheme, which is a predictive method that gives an estimate of the risk from urine stained or pigmented fibre contamination in a sale lot. It utilises information available from the classer's specification form filled out at the time of shearing.
A database of processed sale lots has been collected and utilised in refining the decision scheme, and the probabilities of a sale lot being placed in a particular risk category have been assessed.
Trials have been carried out to determine the relationship between age and pigmented fibre numbers in sheep. These trials highlight the problem of identifying sheep with a high risk of having isolated pigmented fibres as opposed to the general awareness of visible "black wool" on the sheep. This same awareness does not always apply to urine stained wool, where the importance of the interval between crutching and shearing has been demonstrated.
This paper discusses trials leading to the re-evaluation of the Dark Fibre Risk Scheme. It addresses the question of the possible inclusion of a dark fibre risk level in the sale catalogue, and its possible use by brokers and exporters in the support of existing quality assurance programs for the benefit of industry.
Citation
"Dark Fibre Risk and Prediction", Burbidge A. & McInnes C.B., Seminar Proceedings: Specification of Australian Wool and Its Implications for Marketing and Processing, CSIRO Division of Wool Technology & the International Wool Secretariat, November 1994