Residue Analysis
Polymeric residues remaining after sulphuric acid hydrolysis define the chemical maturity of flax stalks. Laboratory technicians identify acid insoluble lignin as the recalcitrant portion of the cell wall that resists liquid digestion during the retting assessment. This substance determines the final stiffness of the scutched fibre.
High concentrations of the polymer indicate over-mature stalks that require aggressive mechanical processing.
Extraction Method
Standardised testing involves grinding the flax straw into a fine powder before subjecting it to two stages of acid treatment. The resulting solid mass of acid insoluble lignin is filtered and then dried before being weighed to determine its percentage relative to the total dry matter. Accurate weighing ensures the mill adjusts its chemical bath concentrations to prevent brittle yarn.
Variations in the concentration of these residues often correlate with the geographical origin of the flax crop.
Spinning Outcome
Coarse yarns result from excessive levels of the compound because the substance prevents the individual fibres from sliding past each other during the drawing stage. When mills process batches with high acid insoluble lignin content, the spinning frames operate at lower speeds to reduce breakages. Finished cloth made from such material feels harsh to the touch.
