Understanding Physical Chain of Custody versus Mass Balance Credit Swapping
Physical chain of custody locks raw fiber origin to individual yarn bolts, while mass balance credit swapping balances paper accounts without physical tracing.
Tow Fiber Separation
Mechanical Classification
Carding and combing processes divide raw flax into long, high-value line fibres and short, coarser fibres that are processed separately. This mechanical sorting is known as tow fiber separation, and it isolates the short bypass fibres from the premium linen line fibres during the initial preparation stages. This process ensures that the long fibres can be spun into fine, high-strength yarns while the shorter fibres are directed toward coarser applications like twine or heavy canvas.
Without this extraction, the presence of short fibres in the drafting zone would cause frequent yarn breakages and produce an uneven fabric surface. Modern combing machines automate this process to achieve highly consistent fibre lengths.
Process Flow
The raw flax passes through a series of spiked pins that catch the longer strands while allowing the shorter elements to fall away. Following tow fiber separation, the short fibres are gathered by pneumatic suction systems and compressed into separate bales for transport. This automated collection keeps the spinning preparation area free from airborne dust.
Economic Utilization
Spinning mills sell the separated short fibres to secondary manufacturers or spin them into coarse yarns for industrial textiles. Although less valuable than line fibres, the material resulting from tow fiber separation represents a valuable secondary product stream that improves the overall yield of the flax processing plant. This utilization prevents material waste and supports the economic efficiency of the mill.