Fibre Standard
Bast fiber length specification ISO 5079 determines breaking load and elongation in single flax fibers pulled from hackled bundles during preparation for wet spinning. Chinese mills apply this protocol to dry or conditioned filaments clamped between pneumatic jaws on constant rate of extension testing machines. Operators mount individual strands across a twenty millimetre gauge length and draw the material apart at a preset speed until fracture occurs.
Tensile force registers continuously through a load cell linked to digital acquisition software. Applied tension reveals structural maturity across different retted flax batches received from provincial suppliers. Results establish mechanical readiness prior to rove drawing and fine drafting frames.
Lower breaking loads signal overretted cell walls that break prematurely during high speed drafting. Excessive elongation indicates underretted pectin still binding microfibrils together inside the technical fibre. Technicians record breaking tenacity in centinewtons per tex to correlate raw material strength with subsequent yarn irregularity.
Testing stops strictly at the single fibre level and yields no direct correlation to multi filament tow performance or final twist stability in spun yarn.
Yarn Grade
Spinning mills classify intermediate sliver quality by comparing measured tenacity against mill specific acceptance limits rather than raw buyer orders. Internal tolerances govern drafting behaviour and twist multipliers on ring frames producing fine counts for export markets. Mill grading protocols require continuous monitoring of breaking tenacity distribution across daily production lots.
High variability demands immediate adjustment on gill boxes to maintain uniform linear density. Laboratory technicians sample bobbins directly from output rails after finishing passes. Data feeds process control charts located near the wet spinning floor.
Export buyers enforce distinct purchase contracts that specify minimum breaking loads for finished yarns, which diverge from internal mill processing thresholds.
Export Contract
Commercial delivery documents reference agreed tensile metrics to certify batch compliance before ocean shipment from coastal ports. Overseas buyers inspect independent laboratory certificates attached to shipping bundles to verify mechanical properties. Acceptance criteria depend entirely on contractual thresholds negotiated prior to raw material dispatch.
Disputes regarding tensile strength trigger arbitration based on retained reference samples stored under controlled atmospheric conditions. Final liability rests on certified breaking load averages recorded during initial spinning mill intake testing.
