Most silk is made from a natural filament produced by the mulberry silkworm in the construction of its cocoon. The silk filament is strong, lustrous, and fine. It produces a high-quality luxury fabric which is expensive to buy.
Cultivation of the silkworm is known as sericulture. Commercial silk farms produce the majority of silk, where silkworm pupae are bred to produce a white coloured silk thread. About 2500 silkworms are required to produce one pound in weight of raw silk. After approximately 35 days and 4 moltings, the pupae are 10,000 times heavier than when hatched and are ready to begin spinning a cocoon. The silkworm will have eaten 50,000 times its initial weight in plant material. Its maximum size is 7.5cm long. It takes the pupae up to 8 days to spin their cocoon and the thread they spin is approximately 1 mile long.
To harvest the silk, before the adult moths emerge the pupae are killed by either dipping them in boiling water or by piercing them with a needle. The cocoons are then soaked in boiling water to soften the sericin (which holds the silk fibres together in a cocoon shape) and the whole cocoon is unravelled as one continuous thread (called reeling). Between 3 and 10 silk threads are combined to make a strong filament, which is then woven into fabric. A variety of patterns can be woven into the silk. Commercially made silk is easily dyed and therefore it is available in many colours.
The largest producer of commercial silk is China, although many other countries including India, Uzbekistan, Brazil and Thailand also produce it.
As the process of harvesting the silk from the cocoon kills the larvae, silk production is criticised by animal welfare organisations. However, ethical silk is now available where no silkworms are harmed or killed in the production process as the silk is extracted after the silkworm has completed metamorphosis and emerged from the cocoon as a moth. The silk is degummed and spun like other fibre, instead of being reeled. The method involves managing moths and controlling the numbers of eggs that can hatch. It is usually made in India and is known as Peace or Ahimsa silk.
Types of silk fabric
There are many types of silk fabric produced. These are the most well-known:
Charmeuse: A lightweight silk woven with a satin weave (where a warp thread crosses over three or more of the weft threads) which makes the front of the fabric have a reflective satin finish and the back have a dull finish. Drapes well – used for underwear, blouses etc.
Chiffon: A lightweight, smooth and lustrous plain weave fabric which is sheer. It drapes well and has a slippery texture. Frays easily. Commonly used in evening wear.
Crepe de chine: Woven in a plain weave with a crêpe (textured) finish. Produced in either a soft finish or a hard finish. The hard finish holds its shape well.
Dupioni Silk: A crisp, quite stiff fabric which holds its shape well. Produced by using fine warp threads and uneven weft threads made from two or more entangled silk cocoons. This produces a tightly-woven but lustrous surface with slubs in it. It is often woven with different colours of threads scattered through the warp and weft which gives an iridescent effect. It is also often woven into plaid or striped patterns. It is suitable for embroidered finishes. Often used for bridal and special occasion wear and upholstery.
Habutai: A sheer basic plain weave fabric that is soft and drapes well - usually used as garment lining.
Organza: A fine, lightweight, sheer fabric with a crisp finish, that is ideal for bridalwear and evening wear. Often used as an outer layer, also used to create full skirts.
Shantung: A medium weight plain weave fabric that has a slubbed effect. Similar to Dupioni silk, but thinner and with a more sophisticated and polished appearance. Often used for bridal gowns.
Taffeta: A good quality smooth and crisp fabric that holds its shape well and rustles when moved. Used for ball gowns, wedding dresses, corsets, curtains and wall coverings. It can be woven with different coloured warp and weft threads, giving it a ‘shot’ appearance that reflects light in interesting ways.
Tussah: Made from wild tussah silk worms that eat juniper and oak leaves. Tends to be coarser and less lustrous than mulberry silk and has an uneven appearance.
Tulle: A lightweight, extremely fine, machine-made hexagonal shape netting which is often used for bridal veils.
Voile: A plain, loosely woven silk that is thin, semi-transparent and lightweight. Often used for window dressing.
Caring for silk clothes
Silk is a beautiful fabric but tricky to care for. Find out how to keep silk clothes and accessories looking great for longer in our guide to washing silk.