Calculating Raw Linen Greige Off-Loom Mass Loss
Off loom mass loss in linen greige averages 14 to 22 percent, requiring correction for sizing pickup, moisture regain, and non cellulosic scour extraction.
Alkaline Scouring Loss
Processing Percentage
Quantitative reduction in dry weight observed after raw flax fabric undergoes hot treatment with caustic soda solutions provides a measure of pretreatment efficiency. This figure represents the alkaline scouring loss. It indicates the amount of pectins, waxes, oils and hemicelluloses removed from the fibre wall to improve absorbency before dyeing.
Precise measurement involves comparing the weight of the oven-dry greige fabric against the weight of the same specimen after the scouring cycle completes.
Chemical Mechanism
Heavy immersion in a boiling sodium hydroxide bath breaks down the natural gums that bind flax fibres together. While scouring improves the hand feel and dye uptake, excessive alkaline scouring loss suggests over-processing that weakens the cellulose structure. Mill technicians monitor the concentration of the alkali and the duration of the boil to prevent the degradation of the primary fibre strength.
Temperatures typically remain near 100 degrees Celsius to ensure the saponification of fats and the dissolution of residual shive particles remaining from the scutching stage.
Production Variable
Variation in this metric alters the final fabric density and the amount of dye required to reach a specific shade. High loss rates often correlate with lower tensile strength in the warp direction. A lab report documenting these figures helps the finishing department adjust its chemical recipes for subsequent bleaching or softening steps.