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  • Harmonization of rapid machine testing of fibre quality

    Chapter 2 - Cotton value addition - Harmonization of rapid machine testing of fibre qu 


    It is a vastly different challenge to utilize an HVI for process control within a textile mill than to use a network of HVIs to classify, buy and sell cotton on the world market. HVI machines within companies do not have to be harmonized with other machines outside those companies. Thus, these HVIs do not have to be accurate (i.e. provide the ‘true value’ of the fibre property measured). As long as they are acceptably precise (i.e. produce measurements that are ‘repeatable’), then the operators of the mill can learn how to advantageously apply the measurements toward the effective utilization of cottons.

    If, however, cotton is to be bought, shipped and paid for based on stipulated values of the fibre properties, then the HVI machines have to be both accurate and precise. The ‘official’ classification instruments must be the arbiters of the ‘true values’ for the fibre properties measured. In an open global market, such authority cannot be mandated; it is a matter of trust, which must be earned and justified repeatedly. Therefore, the HVI machines used for official test results must be continuously harmonized with one another over disparate locations and times. Achieving this is both complicated and costly.

    Up to now, only the following parameters are rated as sufficiently reliable by the ICAC Task Force on Commercial Standardization of Instrument Testing of Cotton (CSITC):

    • Micronaire;
    • Strength, based on HVICCS calibration;
    • Length (UHML, based on HVICCS calibration);
    • Length Uniformity Index (UI);
    • Colour Reflectance (Rd);
    • Colour Yellowness (+b).