Silk was used extensively in the Norwich textiles industry as a fabric in its own right. Alternatively, it could be added as an extra thread with worsted to provide a decorative sheen, so called ‘half-silks’. It was strong, and so suitable for warp threads. Its fineness and lustre was second to none, and its use helped Norwich develop the luxury end of its market. Silk also dyed well, producing rich, luminous colours.

Silk was farmed in China and the Far East from early times, and is produced from the cocoons made by the larvae of the silk worm moth (Bombyx mori). The cocoon is made from a single continuous thread of up to 900m. long. The cocoons were thrown into boiling water to kill the worms and make the cocoons easier to unravel. Most silk arrived as raw silk skeins from Bengal. In Norwich it was sorted into quality, washed and dried. During the ‘first winding’ it was wound from the skein to a bobbin. In ‘second winding’ it was passed from one bobbin to another and the thread inspected for flaws. The bobbins then were placed in a throwing frame to insert twists into the thread. ‘Doubling’ or ‘folding’ followed, during which threads were wound together to increase the diameter of the final thread. Finally,the thread was steamed to set the twist and ‘sized’ by weight.

Some more expensive thrown silk was imported from Italy, and also the inferior ‘spun silk’, produced from throwing and cocoon waste was produced and used in the City. At the peak of production of Norwich crape, mulberry trees were planted to feed silk worms farmed in the city.