Cocoons with holes and double cocoons produced by two silkworms are used as material for silk yarn.
Cocoons unsuitable for raw silk are processed into silk yarn without being wasted.
Cocoons become softer when boiled in lye or sodium sulfite, as sericin around their fibers are dissolved.
These cocoons are then unwound to a flossy state.
Floss silk is slowly pulled out by hand and spun with fingertips.
The hand-twisted silk yarns become stronger by further twining them on spinning wheels.
The yarns are rolled up from the pipe onto the skein with reeling machines.