Learning Lab

Silkworms feed on mulberry leaves, spinning cocoon filaments  from their mouths to make their cocoons. Silk is made from these cocoons.

Silkworms  ~Their Lifecycle~

p01The lifecycle of a silkworm involves a complete metamorphosis, from egg to larva to pupa to imago, in this case a moth. The term “silkworm” refers to the larval stage. The insect lives from May to October, during the season when mulberry leaves are available. It takes about thirty days from hatching until cocoon formation, which it spins over two full days.


Silk Production  ~From Cocoon to Silk~

p02Silkworms spin cocoon filaments and form cocoons  prior to entering their pupal stage.The silk industry produces raw silk from these cocoons. Silk production flourished in Okaya from 1900 to 1930, accounting for about a quarter of Japan’s raw silk output and making it a center of the nation’s silk industry at the time.



Silk    ~Its Appeal~

p03Silk has many attractive qualities. Lustrous and flexible, it colors vividly with both chemical and plant based dyes. It is warm and breathable, and it feels natural against the skin. Further, silk is biodegradable, flame resistant, and absorbs ultraviolet rays. More than anything, the secret of its appeal lies in its beauty. There is no other fiber quite like it.


The Transformation of Spinning Technology

In June of 1859, Yokohama opened its port for business. At that time the silk fiber produced in Okaya was entirely reeled with simple tools. In time, the gear turned Joshu Reeling tools were introduced and fiber quality and production efficiency improved.

In 1870 , the reeling machines produced in Italy were introduced in Gunma Prefecture, and in 1872 the Tomioka Silk Mill, a government managed factory, was established. French type reeling machines were imported for it, and quality and production efficiency of raw silk continued to improve.

Okaya’s Daijiro Takei was familiar with both of these machine types, and he took the best of each and created the Suwa type Reeling Machine. It was rapidly adopted throughout the country, leading to a great influx of foreign currency, and helping lay the foundation for Japan’s modernization.

Around 1910, the Suwa type Reeling Machine became obsolete when Naosaburo Minorikawa developed his multi-end reeling machine. Its success was heralded by twenty domestic machine manufacturers who developed independent versions. Among them, Okaya’s Masuzawa Machineries company Retail developed a model that accounted for 70 percent of the national share.

Then, in 1955, as silk quality became better during reeling, Sadao Oki of Okaya’s Department of Forestry and Agriculture developed a “Silk Size Detector.” Used in automatic silk reeling machines, it detected how fine the thread was and automatically added individual cocoon filments. In this way, Japan became the leader of silk reeling technology in the world.