Gravimetric and Optical Quantification Protocols for Bast Defect Content
Gravimetric digestion provides absolute mass baseline proof for bast defects, while optical scanning provides fast surface area sorting requiring lot calibration.
IWTO 14
Fibre Length
International wool textile organisation 14 defines the standard method for determining the mean fibre length and the distribution of fibre lengths in wool tops using the comb sorter method. This procedure establishes a systematic protocol for the manual measurement of individual fibres from a representative specimen extracted from a staple or top. Technicians arrange the fibres in order of length on a velvet board to construct a length diagram from which the mean length and the coefficient of variation are calculated.
Results derived from this procedure provide the essential data for assessing the spinning potential of a lot prior to conversion into yarn.
Test Application
Mechanical processing in Chinese linen mills relies on precise fibre length data to adjust carding machine settings and drafting roller pressures. Linen spinning requires a high degree of uniformity to prevent excessive fibre breakage and to maintain consistent yarn tension during the ring spinning or rotor spinning stages. Where the top shows a high variance in length, the drafting zone experiences uneven distribution, leading to thin sections or slubs in the finished product.
Proper application of the testing method prevents the procurement of raw materials that fail to meet the performance threshold of high speed spinning frames. Documentation of these findings occurs in the laboratory test report which accompanies the lot through the warehouse and into the production cycle as a verifiable record of fibre quality.
Quality Verification
Acceptance of a shipment often depends on the alignment between the mill test report and the buyer specified tolerance limits for fibre length distribution. Commercial agreements frequently stipulate that the mean length measured by the comb sorter method must remain within a predefined range to ensure the machine throughput stays within optimal limits. Mills verify incoming batches by extracting random samples across different sections of the bale to check against the declared classification of the material.
Disputes over the physical characteristics of the wool tops settle by comparing these measurements against the standard, because the precision of the method provides an objective basis for the resolution of quality claims between suppliers and purchasing entities.