Reconciling Wet Processed Linen Weight Loss against Commercial Loom Hour Billing Allowances
Reconciling wet processed linen weight loss against loom hour billing requires adjusting greige pick counts for chemical extraction and structural shrinkage.
Boil off Mass Allowance
Permitted Tolerance
Standard weight loss percentages establish the expected reduction in raw flax density during the boiling and scouring phases of yarn preparation. The boil off mass allowance defines the maximum acceptable decrease in dry fiber weight after starches, natural pectins, hemicellulose, and waxes are chemically removed by alkaline boiling. In Chinese spinning mills, this value is recorded on the wet processing sheet to distinguish between the loss of non-cellulose compounds and actual fiber degradation.
It establishes the baseline against which yarn yield is calculated before warping begins, ensuring that subsequent weaving performance is not compromised by over-processed fibers. This threshold remains a fundamental metric on the mill floor.
Industrial Measurement
Quantitative testing is performed by heating a representative sample of boiled yarn in a ventilated drying oven until a constant mass is reached. This process measures the difference between the dry weight of the gray yarn and the dry weight of the scoured yarn. Since excessive boiling can damage the cellulose chains, the boil off mass allowance must be monitored to ensure the chemical concentration does not weaken the material.
Mill operators use this measurement to adjust bath temperature and caustic soda exposure times.
Financial Settlement
Commercial contracts use the verified weight reduction to adjust the invoiced mass of processed yarn shipments. If the scouring loss exceeds the boil off mass allowance, the buyer applies a financial penalty to compensate for the lost material. This adjustment protects the purchasing weaving mill from paying for non-fibrous mass.