In the process of creating the cocoon, the silkworm wraps the silk thread around its body. After about 8 days from their ascent to the so called bosco, the cocoons were collected, to prevent the butterflies from breaking through the cocoon and making the silk thread unusable.
To ensure that the butterflies died, the cocoons were either dried - by exposing them to the sun, to hot air currents or by placing them in a bag and placing them in the oven for a few hours - or stewed, by blowing water vapor on them.
In the spinning mills, the cocoons were immersed in boiling water to unravel the silk thread.