Physical State
Continuity of the protective polymer or starch film around the circumference of the yarn defines the barrier against mechanical wear. Achieving complete size encapsulation prevents the reed from shredding the flax fibers during the thousands of cycles required to weave a full bolt. This layer must be flexible enough to bend with the yarn but hard enough to resist friction.
Microscopic inspection of the yarn cross-section confirms the presence of an even coating.
Weaving Protection
Shedding and fiber loss decrease when the size film holds the micro-fibrils tightly against the yarn core. Effective size encapsulation acts as a shield that absorbs the impact of the beat-up and the friction of the drop wires. Without this protection, the stiff flax fibers would splinter and break under the high tension of a modern air-jet or rapier loom.
The quality of this coating depends on the viscosity of the size mix.
Desizing Ease
Film thickness and chemistry determine how quickly the coating can be removed during the scouring stage. While heavy size encapsulation provides excellent weaving results, it must remain permeable to the enzymes used in the wash. If the film is too dense or chemically resistant, it can leave residues that cause uneven dyeing.
