Quantifying Bast Fiber Lignin Content for Mill Sourcing
Klason lignin testing combined with wet spinning draft analysis establishes raw flax mill suitability and prevents costly frame end breaks.
Iso 13906
Fibre Verification
Determination of the fineness of raw flax samples occurs through the application of iso 13906. Laboratories utilize this airflow method to establish the resistance to air flow of a plug of flax fibres under specific pressure conditions. The result provides a measurable value for the average fibre diameter, which defines the physical quality of the raw material before it enters the scutching and spinning stages.
Operators pack a fixed mass of flax into a cylindrical chamber and measure the pressure drop as air passes through the consolidated fibre mat. Variations in the resulting airflow rate demonstrate the structural uniformity of the fibre bundles within the batch. This procedure excludes external environmental interference by maintaining controlled humidity and temperature levels throughout the testing interval.
Quality Standard
Consistency in the final linen product relies on the reliable assessment of the raw material fineness recorded by iso 13906. Flax processing mills apply this measurement to determine whether a specific lot meets the requirements for high-count yarn production or instead requires blending with coarser grades to balance the spinning performance. Spinning lines record these data points in the production logs to track the relationship between raw fibre fineness and the subsequent tensile strength of the woven cloth.
Any significant deviation in the measured fineness compared to the expected grade results in immediate adjustments to the draft settings on the spinning frames. Buyers of linen yarn incorporate this metric into their acceptance criteria to ensure the fabric consistency aligns with the intended end use.
Measurement Mechanism
Accurate outcomes depend on the precise calibration of the airflow equipment against standard reference samples before the testing of production lots begins. The device calculates the specific surface area of the flax, which correlates directly to the diameter of the individual fibres. High air resistance indicates thinner, more desirable fibres, while low resistance identifies coarser material that affects the hand and drape of the finished textile.
Proper preparation of the fibre plug prevents channelling and ensures the airflow represents the true average density of the batch. This protocol eliminates the reliance on subjective human assessment during the initial grading of harvested flax.
Determining Critical Lignin Thresholds to Optimize Long Line Flax Recovery in Wet Spinning
Optimal long line flax wet spinning recovery requires raw fiber Klason lignin held between 1.8 and 2.5 wt% to maximize hackling yield and prevent end breakage.