Fluid Property
Fluid characteristic measures the internal friction and resistance to flow of the starch or polymer solution applied to warp yarns. Rheological properties of the sizing bath determine how well the liquid penetrates the flax bundle and coats the outer surface. Proper size liquor viscosity ensures that the yarn receives a uniform protective film without becoming overly saturated or insufficiently coated.
If the solution is too thick, it forms a heavy crust that flakes off during weaving.
Thermal Management
Heating the mixture reduces the bond strength between polymer chains and allows for easier application at high speeds. Monitoring the size liquor viscosity requires constant temperature control because even a slight drop can cause the starch to retrogress and gel. Mill operators use automatic viscosity controllers to inject water or steam and maintain the target flow rate throughout the batch.
Protective Balance
Low viscosity promotes deep migration into the core of the yarn and strengthens the internal structure against the tension of the loom. High viscosity creates a thicker surface shield that resists abrasion from the drop wires and healds. Finding the balance between these two states is necessary for weaving dense linen cloths that require high levels of mechanical protection.
The operator adjusts the chemical concentration based on the yarn count and the loom speed to prevent excessive shedding or breakages.
