Cotton Fiber Identification
Cotton has been an important fiber since its cultivation in the United States by colonists in the 16th century. Since the cotton gin's invention in the 18th century, cotton has spread to more than 80 countries and makes up 56 percent of all fibers used for clothing and home furnishings in the United States. The US alone produced 3.8 million tons of cotton a year and consumes 1.7 million tons a year as well (Hegde, Dahiya and Kamath 1). Cotton can be identified by visual inspection, burn tests, microscopy and solubility tests.
Cotton fiber is identified in many different ways and is characterized in numerous categories. It is a natural cellulosic fiber and has many characteristics. Cotton has comfortable soft hand, color retention, good absorbency, prints well, dry cleanable, machine washable, drapes well, has good strength and it is easy to handle and sew (Hegde, Dahiya and Kamath 1). Cotton is 20 percent stronger when it is wet, and has relatively low elasticity. Cotton also decomposes when it is exposed to temperatures higher 300 degrees (Hegde, Dahiya and Kamath 1).
When using visual inspection, it is important to look at the appearance and hand of the fiber. Judging the quality of cotton, there are many ways to judge the quality of the fiber. The first way to judge the quality of cotton is by the grade. This is chosen by the external appearance of the cotton, as well as the brightness of the fiber ("Fabric Identification"). It is also important to look at the color of the cotton, and how white it is. Another way to judge the quality of cotton is the color. There are many different colors that cotton can come in ranging from white to gray as well as red shades (Hegde, Dahiya and Kamath 1). Length is another factor weighed in to show the quality of cotton. One type is upland cottons, which range in length from seven eighths to one and a quarter inches. They were developed from cottons native to Mexico and Central America (Kadolph 43). There are also long staple cottons which were developed in Egypt and South America. Lastly, there are short staple cottons, which are less than three quarters of an inch long and come from India and Eastern Asia (Kadolph 43). It is also important to look at the luster, or lack of luster as well as the body, texture and hand.
In order to identify a fiber's composition, many times a burn test will be used. When doing a burn test, it is important to use a well ventilated area (Goodway). Then the fiber should be raveled out and several yarns should be exposed to determine if they have the same fiber (Kadolph 34). The yarn is then held horizontically. The yarn should be held with tweezers and it should be moved slowly into the flame, which can be repeated several times. During a burn test for cotton it does not fuse or shrink from the flame when approaching it. Cotton burns with a light gray smoke when in the flame. After it is removed from the flame, it continues to burn. The ash is gray and feathery with a smooth edge and is easily crumbled, the odor is like burning paper (Kadolph 34). Burn tests do not work to identify blended fibers.
Using microscopy is very helpful when identifying natural fibers. When using microscopy, a piece of the yarn is placed on a slide with distilled water. The slide is then observed under a microscope (Kadolph 34). Cotton has the form of a long, hollow tube (Goodway). The solubility test is more helpful for manufactured fibers, than natural fibers. Cotton is dissolved best in sulfuric acid of 70 percent concentration at 38 degrees Celsius (Kadolph 36).
Cotton can be identified and classified in many different ways. Since cotton is such an important fiber, it is essential to know how to identify it. By using visual inspection, burn tests, microscopy and solubility tests, it is easy to identify cotton fibers.
"Cotton for Nonwovens: A Technical Guide." 2008 Cotton Incorporated. http://www.cottoninc.com/Nonwovens/CottonNonwovens/#ref22.
"Fabric Identification." Copyright Fabrics.net. Spokane, WA. `http://www.fabrics.net/fabricsr.asp.
Goodway, Martha. "Fiber Identification in Practice." Journal of the American Institute for Conservation, Vol. 26, No. 1 (Spring, 1987), pp. 27-44.
Hegde, Raghavendra, Atul Dahiya and M.G. Kamath. "Cotton Fibers." April 2004. University of Tennessee- Knoxville. 22 Sep 2008. http://www.engr.utk.edu/mse/pages/textiles/cotton%20fibers.htm.
Kadolph, Sara J. "Fiber Identification." Textiles. 10th ed. 2007.
By Megan McCalla
Cotton Fiber Identification
Cotton is one of the most prominent and significant fibers in today's global society. With cotton production in more than 80 countries, cotton's influence on our economy and lifestyle has been extremely monumental. With cotton being such a vital textile in everyday surroundings, it is important to understand the different properties, effects, and physical structure of cotton to be able to identify its fibers from other various fibers. According to Dr. Ha-Brookshire and Cotton Inc., there are numerous methods and ways and to identify cotton. For example, to be able to thoroughly identify cotton fibers, one must look at the physical properties with visual inspection, conduct a burn test and solubility tests, use microscopy to examine the fiber, and lastly, understand the effects of chemicals and heat on cotton.
First, one must study the physical components of the fiber, i.e. the length, luster, body, texture, and the hand. Cotton is a staple fiber, meaning it is short in length (about 1/2-2"). However, cotton does come in various staple lengths. For example, upland cotton is approximately 7/8-1 1/4"; long staple cotton, 1 5/16 -1 1/2"; and short staple cotton, less than 3/4". Cotton, also generally tends to have low luster, except in the case of long staple cottons, which has a high degree of luster. The texture and hand of a cotton fiber depends more on the yarn and the fabric (Ha-Brookshire).
Secondly, a good indication if it is a natural fiber is to conduct a burn test. Natural fibers, including cotton, burn easily with a light gray smoke. It smells like burning paper and burns into a gray, feathery ash with smooth edges. Another good test to run to identify a cotton fiber is a solubility test. Cotton is soluble in one the strongest acids, cold sulfuric acid, 80% concentrated ("U.S. Cotton Fiber Chart").
Another excellent method for cotton fiber identification is microscopy, simply, looking at a fiber under the microscope. A cotton fiber is composed of the cuticle, the primary wall, the secondary wall, and the inner most layer, the lumen.
Lastly, it is also important to understand the effects of chemicals and heat to assist in identifying different fibers. Cotton breaks into small pieces in hot weak acids and cold strong acids. It also bleaches in peroxides. Cotton is "highly resistant to thermal deformation and degradation" ("U.S. Cotton Fiber Chart").
With these various methods and a good understanding of the properties of cotton, cotton fiber identification is made extremely easy, especially since it is such a dominant textile in today's society.
Hedge, Raghavendra R., Atul Dahiya, and M.G. Kamath. "Cotton Fibers." Apr. 2004. 17
Sept. 2008 <http://www.engr.utk.edu/mse/pages/textiles/cotton%20fibers.htm>
"U.S. Cotton Fiber Chart." Cotton Incorporated. 17 Sept. 2008
Kadolph, Sara J., Textiles. 10th ed. Upper Saddle River, NJ: Pearson Education, Inc.,
Dr. Ha-Brookshire. In class notes.
By Lorrin Lynn
Copyright © 2008 Department of Textile and Apparel Management
University of Missouri
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