Fabric production is the process by which textiles are produced from various types of fibers and sources. Although there are several different methods of fabric production depending upon the type of fiber used, the most common production method explained is that of cotton. This article will focus on the production of cotton as a typical example of textiles derived from plant sources. Specific production methods for other types of textiles from different plants or animals are listed on their respective pages.
Cultivation and growth of fibers Edit
The process of creating fabrics begins with the cultivation of crops which yield natural fibers, which are the raw materials used to create thread, which are aptly named "fiber crops". There are several different types of fiber crop from various regions in the world, each with distinctive properties which in turn produce distinctive types of thread.
The most commonly used fiber crop in textile production is cotton. Cotton is a family of plants which require environments which provide long periods of sunshine, and a minimum of 120 to 180 frost-free days, so that the fibers can be taken from the plant. If there is any presence of frost, this tends to freeze the high water content of the growing cotton, which prevents the bundle of fibers known as the "boll", from growing, so therefore it is essential that there are long, hot and dry summers, with low humidity. Because cotton requires these conditions, it is grown in a specific region of the earth which can provide them (specifically between 45 degrees north and 35 degrees south) in which the cotton belt of the United States, areas of Mexico, China, India, Pakistan and Uzbekistan, Egypt, Syria and others fall.
The planting of the cotton crop begins between late September and mid-November, where the seeds of the cotton plant are sown in heavy or "clay" soil, which retains a good number of minerals required to nourish the cotton plant, retains water well and drains slowly, which provides ideal conditions for cotton to grow. Although cotton is a perennial, meaning it lives for around two years, the plant is generally re-grown after a single year in order to prevent disease and to combat a legendary pest in cotton crops known as the Boll Weevil.
Cotton grows as other plants do, though photosynthesis. The seed of the cotton gradually grows small, "seed leaves" known as cotyledons. After two to four weeks, the process of photosynthesis is turned over to the new, or "true" leaves of the plant that have grown sufficiently, which then aid the plant in growing a taller stem and deeper roots, and a greater number of leaves. After around five to seven weeks, leaves known as "bracts" begin to develop and eventually grow from each side of the stem, and a small bud known as a "square" begins to grow. As the square grows larger, it eventually pushes upagainst the bracts and then opens up into a pinkish-white flower, which is then pollinated by itself or another cotton plant.
Once the cotton plant is pollinated, the flower begins to wither and exposes a small green "boll", which eventually develops into a bundle of fibers, which over time develop with cellulose into stronger, thicker cotton fibers. In general, each fig-sized boll contains up to 500,000 fibers, and each cotton plant bears up to 100 bolls. Within 45 days of the boll appearing, it begins to naturally split open along the segments called "carpels" to reveal several segments or "locks" of cotton attached to "burs", which hold the cotton in place. The result is a dried and fluffed cotton fiber, ready to be picked.
Harvesting and picking Edit
Once the cotton plant has split open, the plant is ready to be picked, either by hand, or by machine. The most prevalent method worldwide is hand-picking, which is more inefficient than machine picking, which is a modernised method of cotton picking.
A mechanised harvester is a machine similar to a combine harvester which has a "head", through which the cotton plant is fed. As the cotton passes into the head, the cotton locks attached to the burs of the cotton plant are detatched by several rotating spindles, along with other parts of the plant which fall into the machine. The remnants of the plant then pass from the spindles to a rounded rubber stack called a "doffer", which takes any stuck cotton from the spindles of the machine. Once the cotton has been cleared from the blades of the spindles, a vacuum pulls the remnants of the plant into the "basket" of the machine, which holds the processed cotton plant. The spindles are then cleaned with water and the process is repeated.
Hand picking follows the same process, although it is performed by hand and stored in portable containers that workers carry with them. Once both mechanical and manual processes have ended collecting and processing the cotton, what remains is a mass of cotton locks which contains seeds from the plant and other material that needs to be separated in order for cotton to be processed. Cotton is either stored in trailers, which can be somewhat problematic due to cotton harvesters picking more cotton than can be stored and processed; this problem tends to be resolved through the use of a module builder, which compresses the cotton into much smaller, unprocessed bales, which can then be uncompressed and processed.
Ethical concerns Edit
Although harvesting is common with machinery in areas of Europe and the United States, there are still areas such as Uzbekistan, where a large proportion of the world's cotton is picked by hand by state-enforced forced labour. Uzbekistan has a particularly appalling approach to maintaining its cotton export, and involves the use of over a million children and adults from all backgrounds, forcibly made to prepare fields and pick cotton in harsh conditions throughout the year under threat of beatings, expulsion or loss of benefits if they fail to meet their quota.
In a missive from the International Cotton Advisory Committee on cotton production it was stated that 30% of the world's cotton is harvested using automated machinery, while the remainder is picked by human beings. In most European countries, the practice of hand-picking is limited and appears to be declining. However, the practice of hand-picking and cotton production is heavily distributed in developing countries, with many countries such as Bolivia, Ecuador, India, Pakistan, Paraguay, Turkey and Zimbabwe producing a majority of cotton.
Ginning, baling and classing Edit
In order for the cotton material or "lint" to be processed into usable material, the seeds and other material that became embedded in the fibers need to be removed. In manual processing, the seeds are removed by hand, which is an extensively labour-intensive process, and in other methods of production, an automated machine known as the cotton gin is used.The cotton gin separates the cotton lint from the other material by pulling the thin fibers of the cotton through mesh, through which seeds cannot pass. Depending on the length of the fibers, or "staple", different gins are used. For short-staple cotton, the saw gin is used, whereas for longer-staple and more delicate cotton, the roller gin is used, which rolls the cotton between rotating bars or "rollers", which are very close together and prevent seeds and other material from passing through.
The end result of the ginning process is a processed mass of lint, which is usually compressed into a bale. The bale itself is compressed to a standardised size known as the "Universal Density Bale" or "Gin Universal Density Bale" which is set by the Joint Cotton Industry Bale Packaging Committee (JCIBPC). The size of the bale is specifically between 1.37-1.40 meters long, 0.51-0.53 meters tall, and 0.84 meters wide. The bales are a rounded shape, and tend to bulge. As such, the width of the bale is referred to as the "bulge".
The quality of the cotton in the bale is then "classed" according to a cotton quality scheme so that the value of the cotton produced can be determined. When the cotton is sold between states in the United States of America, for instance, the cotton quality is classed by the United States Department of Agriculture (USDA) which determines the sale price of cotton. Similar programs within the European Union exist, which are implemented on a national level by member states. In the developing countries, the quality of the cotton is generally considered to be much lower than in developed countries, and in countries such as Pakistan, lack widespread quality programs to maintain the level of cotton production and quality.
Bale breaking, willowing and scutching Edit
The cotton lint bales that have been produced are then un-baled or decompressed, they are placed into a machine known as a bale breaker to produced a mass of lint which is not compressed or bound together. In some cases where the cotton is dirty due to transportation or import, a machine called a willower is used. The willow is generally a rotating drum, into which, cotton is loaded and washed with water or other materials to clean off any additional dirt which has accumulated on the cotton lint. The mechanism of the willower is a rotating drum with a thin mesh used to separate out other impurities, similar to the working of a cotton gin.
In addition to the willower, the scutcher is used for a similar purpose: to remove any impurities in cotton. The scutcher works by beating the fabric to remove any seeds or impurities from it, and ion older machines uses a perforated drum known as a finisher scutcher, over which the cotton is rolled. In modern scutching machines, the finisher is either incorporated into the beating process or is absent due to the efficiency of the "beater bars" which beat the impurities from the cotton lint. After the lint has been willowed and scutched, the result is a long sheet of wadded cotton known as a lap.
The lap which is created in the scutching process is fed into a machine known as a carder. The carding machine consists of a large drum, through which the cotton lap passes, and a series of smaller drums which have small metal teeth on them to align the fibers of the cotton. As the lap passes through the carding machine, the metal teeth on the drums become progressively smaller, and the fibers of to cotton are brought together into thick rope-like material approximately 2.5cm in width known as a "sliver". Because in some places, the sliver may not be of a uniform thickness, the sliver can be combed to remove any of the short fibers and retain the longer ones, and then combined with other slivers of similar length to increase the strength of the cotton fibers when combined.