Material Reduction
Treating linen yarns or fabrics with concentrated sodium hydroxide solutions leads to a reduction in total dry weight due to the extraction of non-cellulosic components. This decrease in mass is mercerization yield loss, which is a standard consequence of the swelling and cleaning process.
Process Mechanism
High-grade linen production utilizes caustic soda to swell the cottonized or linen fibres, converting the cellulose structure and improving dye affinity. During this chemical reaction, the mercerization yield loss occurs as soluble hemicelluloses, pectins and short-chain cellulose molecules dissolve into the bath. This weight reduction typically ranges from three to six percent of the starting dry weight, depending on the temperature and concentration of the alkali.
The loss is monitored by weighing oven-dry samples before and after the wet treatment to ensure it remains within the allowed limits.
Economic Impact
Finishing mills must factor this weight reduction into their production costs and yarn requirements to ensure they deliver the correct quantity of finished goods. When mercerization yield loss exceeds the planned allowance, it indicates that the chemical treatment was too aggressive or that the raw yarn contained excessive impurities. This leads to higher raw material consumption to achieve the target fabric weight per square meter, reducing the profitability of the order.
The finishing logs must record these losses to allow adjustments in the yarn feeding rates.
