The question we’re about to answer is: “what is silk made of?”
When you hear about silk, a few things come to mind. We immediately picture a delicate appearance, smooth surfaces that resist odors, and wrinkle resistance. All these are some of the important characteristics of silk that make it loved by many people. Because of the protein structure of silk, it is also among the most hypoallergenic fabrics today. But what is it made of?
What is Silk Made of?
Silk is made from silkworm cocoons grown domestically. These domesticated silkworm cocoons are almost entirely used in commercial purposes. They are caterpillars of certain moth species found in the genus Bombyx. The fibrous cocoons of silkworm caterpillars are used to make commercial silk (Bombyx species).
To understand this, we must first learn where silk is produced.
Silk is an animal fiber produced by certain insects and arachnids that use the fiber to construct their cocoons and webs, some of which can be used to make fine fabrics.
Because silk is derived from the cocoons of larvae, the majority of the insects raised by the industry do not survive the pupal stage. A single pound of silk requires around 3,000 silkworms must be killed.
Silkworm moth (Bombyx mori) is the most popular caterpillar that has been used for thousands of years in silk production (sericulture). Although the silkworm is native to China, it has been introduced all over the world and has become completely domesticated, with the species no longer being found in the wild.
Where is silk produced?
According to International Silk Association, China is the world’s largest silk manufacturer. With 146,000 metric tonnes of silk produced per year, this East Asian nation far outnumbers its closest competitor, India, which produces only 28,708 metric tonnes of silk per year.
Originally, humans harvested wild silk to create the initial fabrics. While worms spin silk in the wild in parts of many parts of China, India, and Europe, there is never enough wild silk to meet the needs of full-fledged textile production.
What is Silk Made of Chemically?
Silk is a natural protein fiber composed primarily of fibroin, a protein secreted by certain types of insect larvae to form cocoons. While other insects produce silk-like substances, Bombyx mori larvae, which are worms that only live on mulberry trees, produce the majority of the world’s silk.
Silk produces a shimmering optical effect when light is shone on it under some conditions due to the triangular prism-like structure of its fibers. These prisms reflect light at different angles, producing the subtle rainbow hue that has made silk quite popular.
The chemical component of raw silk is also unique.
Raw silk is silk that contains sericin. The gummy substance is usually retained until the yarn or fabric stage. After that, it is removed by boiling the silk in soap and water. This leaves it soft and lustrous with a weight reduction of up to 30%.
Spun silk is created by twisting together short lengths of silk obtained from damaged cocoons or broken off during processing.
People also talk about measurement units for silk. Silk filament yarn thickness is measured in denier, which is the number of grams of weight per 9,000 meters (9,846 yards) of length. Weighting is a process in which silk is treated with a finishing substance, such as metallic salts, to increase weight, density, and draping quality.
While the silk fabric making has grown significantly in the last century, the processes used to create it remain largely unchanged from the ancient world.
Here’s a step-by-step guide to the fascinating process of silk production…
How Is Silk Made?
Step 1: Sericulture
The first step in making silk is sericulture. It is the term used to describe the process of collecting the materials by gathering the silkworms and harvesting their cocoons.
Female silkmoths can lay anywhere from 300 to 500 eggs at once. These eggs hatch into silkworms, which are then incubated in a controlled environment until they develop into larvae (caterpillars).
How long do silkworms take to grow?
To promote growth, the silkworms consume a massive amount of mulberry leaves on a daily basis. It takes about 6 weeks for them to reach their full potential (about 3 inches). They’ll stop eating and start raising their heads at this point, indicating that they’re ready to spin their cocoon.
The silkworm, attached to a secure frame or tree, usually begin spinning its silk cocoon by rotating its body. The rotation comes in a figure-8 movement around 300,000 times – a process that will take 3 to 8 days. Each silkworm produces only one strand of silk, which is about 100 meters long. The thread is held together by a natural gum called sericin.
Step 2: Extracting the thread
After harvesting silkworm cocoons, silkworm breeders usually expose them to high heat to prevent mature worms from emerging. Some animal rights activists object to this practice, claiming that it is possible to harvest silk without killing silkworms, but this claim is not widely accepted.
Silkworks spin their cocoon and eventually enclose themselves inside it, at which point the silk threads can be extracted.
The cocoons are submerged in boiling water to soften and dissolve the gum that holds the cocoon together. This is an important step in the silk production process because it ensures that the continuity of each thread is not harmed.
Each thread is carefully reeled from the cocoon in individual long threads before being wound on a reel. Some sericin may remain on the threads to protect the fibers during processing, but this is usually removed with soap and boiling water.
Step 3: Dyeing of silk
After being washed and degummed, the silk threads are then bleached and dried before the dyeing process begins.
Traditional silk dyeing techniques use natural products found in our environment, such as fruit or indigo plant leaves, to create the dyes. The threads will be soaked in bundles in a pot of boiling indigo leaves and water. This process will be repeated several times over the course of several days to ensure proper color tone and quality.
However, in the commercial manufacture of silk, these traditional dyeing methods have almost become unavailable. Because of technological advancements, manufacturers now use various dyes such as acid dyes or reactive dyes. This provides a wider range of color and shade options to meet a wider range of demand.
Step 4: Spinning of silk
It is important to note that the traditional spinning wheel has always been and will continue to be an important part of the silk production process. Although modern industrial processes can now spin silk threads much faster, it simply mimics the functions of the traditional spinning wheel.
Step 5: Weaving the fabric
Weaving is the process by which the finished piece of silk is created. Silk can be woven in a variety of ways, the most common of which are satin weave, plain weave, and open weave, and the finish of the silk is determined by the type of weave.
The silk threads will be woven at right angles to each other. The two distinct angles are referred to as a warp and a weft. The warp of the fabric will run up and down it, while the weft will run across it.
Step 6: Silk printing
If a piece of silk requires a unique pattern or design, it must be printed after pre-treatment. This can be accomplished in two ways: digital printing or screen printing.
Step 7: Finishing the fabric
Silks must be finished before they can be considered ready for use. Finishing a piece of silk gives it that highly lustrous sheen for which it is famous, and it is the reason that the desired look and feel can be achieved.
Silk finishing can be done in a variety of ways, the most common of which is by applying various chemical treatments, which can add a variety of valuable properties such as fire resistance and crease-proofing.