Silk is a strong, smooth organic fiber that is spun together to make material. It is a protein fiber that is produced by the larvae of the mulberry silkworm. Silk has a shimmery appearance due to the triangular prism shaped structure of the fibers. When light hits silk it is refracted, giving it the appearance of having many colors. Silk is also produced by a number of other insects particularly those that go through metamorphosis such as butterflies and moths. Some species of bees, wasp and ants can also produce silk. Spiders also use silk to spin webs.
The Production of Silk
Even though silk can be produced by many types of insects the silk that is used to make fine textiles and clothing is obtained from the larvae of the mulberry silkworm. These “silkworms” are not actually worms at all, but are the caterpillar of the silk moth. To produce enough silk to be woven into material silkworms are cultivated. Silk moths are kept in special habitats. Specialized paper is laid out for the silk moths to lay their eggs on. These eggs are hatched producing silkworms or baby silk moth caterpillars. These caterpillars are fed fresh mulberry leaves until they have reached approximately 10,000 times the weight they were initially. Once they have reached this stage the silk worms begin to spin a silk cocoon. They spin this cocoon by ejecting threads of liquid silk protein out of the spinnerets on top of their heads. As the liquid silk makes contacts with the air it solidifies creating a cocoon around the caterpillar. In total one cocoon is equal to 1 mile of silk filament. Once the silkworm is completely encased in the cocoon silk harvesters kill most of the caterpillars with heat, which leaving only a few to change into silk moths. These silk moths them continue the cycle and produce more eggs. The cocoons are then harvested and sent to a filature operation.
Once at the filature operation the cocoons are sorted by size, texture and color. These cocoons are then placed in boiling water and turned gently for five minutes to soften the sericin holding the silk fibers together. They are then taken out of the water and a needle is used to find the end of the silk thread. Once the end is found the silk is unwound and spun together, with anywhere from 3 to 10 other strands of silk to form a silk thread. This makes the silk strong enough to be woven into fabrics and textiles. It takes approximately 3,000 cocoons to make 1 pound of silk. The silk is then sent to textile factories to be woven into silk cloth.