Chemical Preparation
Caustic soda solutions applied during boiling break ester linkages within the secondary wall of flax fibres. Lignin digestion alkali destroys residual encrusting polymers holding bast cells together inside the technical filament bundle. Reaction kinetics depend strictly upon active sodium hydroxide concentration and thermal energy delivered to pressure vessels during cooking cycles.
Excessive hydroxide strength degrades cellulose chains while insufficient alkalinity leaves residual pitch unremoved before subsequent mechanical processing steps.
Liquor Ratio
Bath volumes dictate chemical mass transfer rates during the alkaline treatment phase of wet preparation. Hydroxide consumption during lignin digestion alkali protocols requires precise replenishment schedules to maintain uniform liquor density across dense vegetable fibre loads. Solution depletion curves show sharp concentration drops within the initial heating interval when non-cellulosic components dissolve rapidly into the aqueous phase.
Technicians monitor residual alkalinity through direct titration against standard acid solutions to verify bath exhaustion before discharge.
Batch Purity
Final acceptance criteria separate processed sliver quality from raw material variability originating in agricultural supply chains. Laboratory technicians measure residual lignin fractions via acid insoluble residue tests to confirm that lignin digestion alkali treatments reached target endpoints. Certified export lots require strict compliance values recorded on mill inspection certificates issued prior to spinning preparation.
Unprocessed bundles failing chemical reduction limits return to caustic boiling tanks for secondary treatment cycles.
