Have you ever looked at a lotus leaf on a rainy day? You may have noticed nothing special besides a large green leaf with some water drops on its surface. But have to ever wonder why these water drops never soak through the leaf? They are always floating on the surface. Likewise, ducks do not get wet but have water rolling down on their plumage.
How does it work? Water repellency can be found in few man-made products like Teflon, Zipel, or 3M Scotch Tape. The phenomenon, how ever, is common in nature. It is amazing that ducks and lotus leaves have such properties without an artificial water repellent coating.
Water repellency is a matter’s property to repel water. Its meaning is quite different from having water resistance or being water proof because it works by having surface tension.
The surface tension is force that liquid sustains the minimum surface area. This is caused by the attracting force in the molecules of liquid. Each molecule is pulled equally in all directions by neighboring liquid molecules, which results zero net force. On the surface of the liquid, the molecules are pulled inwards by other molecules under them. Therefore, all of the molecules at the surface are subject to an inward force of molecular attraction which can be balanced only by the resistance of the liquid to compression. Thus the liquid holds itself together to achieve the lowest surface area possible. This property is surface tension. Due to this property, water drops take the shape of spheres. The stronger surface tension is, the more round the sphere it forms. It becomes flattened if surface tension is weak.
What happens when the two materials with different surface tension meet? The material with stronger surface tension retains its shape and is repelled on the material with weaker one. In the opposite case, the material with weaker surface tension on the stronger one becomes absorbed or flattened. This is an amazing physical property that can be found in many substances of the universe.
Our ancestors understood this property well to invent many useful devices. One of these is papillote, oiled paper. Underlying this invention is the fact that oiled paper pushes out water instead of absorbing it. The reason is that surface tension of water is stronger than that of oil.
The more the discrepancy of surface tension is, the stronger the effect of water repellency. People became to find objects with weaker surface tension such as silicon and paraffin oil.
Although silicon and paraffin oil repel water effectively, these cannot repel similar oil components with similar surface tension. Oil repellency is quite more complicated than water repellency.
Teflon came out in 1938. Teflon is a compound of carbon and fluorine rounded with fluorine molecules with intensive chemical bond, which have less surface tension than oil.
Teflon forms fluorine layer on fabric with strong surface tension such as cotton and prevents it from getting stained with water or oil. The repellency becomes more effective as the fluorine compound molecules get smaller in size and numerous in their number.
Nanotex, which produces Nanocare, asserts that their fluorine molecules are in nano size. Accordingly, the company’s products with stand laundry washing and repel water effectively. These products are mentioned in the chapter,“Nanocare vs. Teflon”in more detail. The sizes of their molecules are around 100 nanometers. It is interesting that the actual size is quite bigger than that of the molecules in Teflon produced by Invista. So one may say that Nanocare is cheating by calling their products nano.
Mercury is the substance with the strongest surface tension on Earth. So it is repelled on the surface of all other matters and forms spheres.
The surface tension of water is 72 dyne/cm. Cotton has exactly the same surface tension of 72 dyne/cm. So cotton cannot repel water and pants made in cotton gets wet in a matter of seconds. Olive oil coating on cotton would result surface tension of 32 dyne/cm. Water on this cotton fabric would be repelled and form beads.
Synthetic fabrics such as nylon (46 dyne/cm) and polyester (43 dyne/cm) have weaker surface tension than water. So they naturally repel water. This is the reason why most bathing suits are made of synthetic fiber. If you want your cotton pants to repel olive oil, cover them with paraffin oil (26 dyne/cm) or silicon (24 dyne/cm). These are actual fabric coating methods. They are called“wax coating”and“silicon coating”.
The substance with the least surface tension is fluorine compound. So far there is no substance with lesser surface tension than this. Teflon made of this fluorine compound has 15 dyne/cm surface tension. So Teflon is invincible against water or oil!
Let’s get back to the lotus leaf. The leaf not only repels water but even prohibits it from making any contact. The water beads on the lotus leaf appear white, not transparent. The reason for this is that water reflects itself since it is not touching the lotus leaf. Total reflection is happening here.
Total reflection is an optical phenomenon that occurs when the light travels from a denser medium (water) to a lesser dense medium (air) at a greater angle than the critical angle. The light stops crossing the boundary altogether and is completely reflected.
The reason that the lotus leaf repels water is its oily surface with weaker surface tension than water. The lotus leaf’s surface tension is similar to that of olive oil, around 32 dyne/cm. So it naturally repels water with surface tension of 72 dyne/cm.
I believe enough has been said about water repellency. There is another interesting phenomenon with these water beads on the lotus leaf. How come they are floating on the leaf?
This is possible because there are micro-mini buds on the leaf’s surface. This bud is only about 1 nanometer. Water forms into beads over these buds and floats on them because they are much smaller in size. Empty space is formed between the buds and water drops and the total reflection occurs. So water is not even touch ing the leaf.
To be exact, the contact dimension of the lotus leaf and a water drop is less then 2~3%. So the water beads cannot stick but roll down. Unlike inert water drops on a plain surface, the water beads on the lotus leaf catch dirt and stains on the leaf when rolling down. The beads actually clean the leaf. This is called the lotus effect.
The core properties in the lotus effect are surface tension and minimization of the contact area. These two have to come together to make the cleansing effect work properly. Some say that the leaf’s buds are entirely responsible for creating the lotus effect but this is wrong. What if we pour alcohol on the leaf?
The surface tension of alcohol is 23 dyne/cm. Since the leaf’s surface tension is about 30 dyne/cm, alcohol will just wet the leaf as shown in the picture. Unlike water, alcohol does not become beads. If water is poured on alcohol, it will be repelled since alcohol has much less surface tension than water.
The surface tension is affected by the temperature. The lower the temperature is, the stronger the surface tension gets. Therefore, hot water has less surface tension than cold water. So cotton pants would get wet easier in hot water.
2008-06-02
The Compact Cotton Yarn
Artificial filaments have smooth surface and luster naturally because they are pulled out through a narrow nozzle. There is a processing called cire that increases the luster. For DuPont’s Trilobal, the shape of the fiber’s cross section is changed to a triangle to maximize the luster. Spark and bright yarn are other names for Trilobal. These days, the shiny artificial filaments are considered as cheap looking and losing popularity. Instead, full dull filaments made by adding dioxide titanium are in demand.
Ironically, cotton fibers made to look shiny like artificial filaments is very expensive. Untreated cotton has tiny fibers on its surface which prevent light reflection. There are many treatments to make shiny cotton fibers but they are quite complicated. Silket is one of these method used for making luster in cotton fibers for knitted fabrics. Cotton is made to look like silk through singeing, the process where tiny fibers on the surface of the fibers are burned away. The treatment is limited to cotton yarns in CM4’s, which are fine and expensive yarns that have been combed at least three times.
Mercerizing is another method that gives luster to cotton fibers. The crushed empty space inside the fiber called lumen is blown up, tightening and straightening the surface of the fiber. The expanded cotton has a smooth and shiny surface. Both silket and mercerizing methods damage the yarns. Making garment out of the damaged yarns can cause serious problems in tear strength.
Compact cotton yarn (CCY) overcomes these problems of silket and mercerizing. The strength of cotton fibers increases up to 20% when they are spun in CCY. Air is applied during the twisting process of spinning to force tiny fibers inward and make the surface of fiber smooth. CCY is thicker and voluminous. The weaving process is also improved by reducing the amount of starch required. Dyeing fabrics made of CCY results bright and even color. The only drawback of CCY is its high price. CCY shirts made in China cost around $3.00 to $4.00.
Ironically, cotton fibers made to look shiny like artificial filaments is very expensive. Untreated cotton has tiny fibers on its surface which prevent light reflection. There are many treatments to make shiny cotton fibers but they are quite complicated. Silket is one of these method used for making luster in cotton fibers for knitted fabrics. Cotton is made to look like silk through singeing, the process where tiny fibers on the surface of the fibers are burned away. The treatment is limited to cotton yarns in CM4’s, which are fine and expensive yarns that have been combed at least three times.
Mercerizing is another method that gives luster to cotton fibers. The crushed empty space inside the fiber called lumen is blown up, tightening and straightening the surface of the fiber. The expanded cotton has a smooth and shiny surface. Both silket and mercerizing methods damage the yarns. Making garment out of the damaged yarns can cause serious problems in tear strength.
Compact cotton yarn (CCY) overcomes these problems of silket and mercerizing. The strength of cotton fibers increases up to 20% when they are spun in CCY. Air is applied during the twisting process of spinning to force tiny fibers inward and make the surface of fiber smooth. CCY is thicker and voluminous. The weaving process is also improved by reducing the amount of starch required. Dyeing fabrics made of CCY results bright and even color. The only drawback of CCY is its high price. CCY shirts made in China cost around $3.00 to $4.00.
Pesticide-free Fabric
A store named“Orga”just opened up near my house. It sounds like a Russian girl’s name but it is actually an organic vegetable shop. These stores are opening up every block since people are more interested in making their lives longer and healthier. I buy homemade yogurt from here. It says it is organic. How can something fermented be organic? This would only mean that yogurt came from a cow that was raised in organic pasture. This is impossible to prove. Although it is non-sense, I just buy it for the simple reason-it taste good.
Likewise, it is difficult to prove that a piece of cotton fabric is organic. A surveillance camera would have to be placed 24 hours. So these are named as colored cotton (non-bleaching and non dyeing) and pesticide-free. They have nothing to do with organic cotton but people recognize them as something more natural. Colored cotton is healthier since chemical solution is not added. Bleaching and dyeing, however, are also proven safe. Colored cotton comes in just 3 basic colors that as faded as the colors of greige fabric. The visual effect is strong and customers believe they are organic.
The cost to create such effect is huge. A simple cardigan made of high-priced colored organic cotton will cost $350. Using organic cotton alone is not a good strategy since the difference is not shown. Customers will not feel much different wearing the organic cardigan from a regular one. So it is all about having the visual effect.
With inorganic cotton, my company has produced fabric that looks just like organic cotton. It is pesticide free, non-bleached, and non-dyed. So it would be the same as organic cotton. The only difference is that it cannot have a special tag written organic cotton.
Likewise, it is difficult to prove that a piece of cotton fabric is organic. A surveillance camera would have to be placed 24 hours. So these are named as colored cotton (non-bleaching and non dyeing) and pesticide-free. They have nothing to do with organic cotton but people recognize them as something more natural. Colored cotton is healthier since chemical solution is not added. Bleaching and dyeing, however, are also proven safe. Colored cotton comes in just 3 basic colors that as faded as the colors of greige fabric. The visual effect is strong and customers believe they are organic.
The cost to create such effect is huge. A simple cardigan made of high-priced colored organic cotton will cost $350. Using organic cotton alone is not a good strategy since the difference is not shown. Customers will not feel much different wearing the organic cardigan from a regular one. So it is all about having the visual effect.
With inorganic cotton, my company has produced fabric that looks just like organic cotton. It is pesticide free, non-bleached, and non-dyed. So it would be the same as organic cotton. The only difference is that it cannot have a special tag written organic cotton.
Organic Cotton
After searching the mall for 3 hours, you finally find the perfect T-shirt. You check out its content label and find it marked 100% Cotton. What does this mean to you? You would probably like the T-shirt more because cotton means something soft, comfortable, and, mo st of all, natural.
Cotton originates from India dating back some 5,000 years. Now about 50% of the world’s garments are made in cotton. We feel easy and comfortable wearing cotton because it is made from a natural substance found in plants-cellulose. It has other excellent properties: white color, soft touch, and superior absorbency.
Behind this goodness, however, lies the dark side of cotton farming. Since growing cotton exhausts soil’s nutrients, a lot of chemical fertilizer is used. This type of unnatural nurturing weakens plants against harmful insects. Therefore, pesticides become necessary. Popular demand for cotton textiles has increased the use of pesticide. Cotton is now the most pesticide-dependent crop in the world, accounting for 25% of all pesticide use.
So is your favorite cotton T-shirt full of pesticide? Of course not! Harmful substances are removed and clothes are tested before they are placed in stores. According to FITI, a testing organization, cotton fabric contains less than 0.1% of pesticide. Dye solutions for cotton are also made safe by removing formalin and azo.
Therefore, it is not the degree of safety that organic and non-organic cotton differ in because both have to have almost 0% pesticide to be sold. The true purpose of organic cotton is to save environment. Every year in the United States, 25 million kilograms of pesticide is used. This is polluting water and earth. In order grow organic cotton, not a drop of pesticide should touch the ground for 3 years and natural fertilizers have to be used.
It has been more than 15 years since organic cotton farming started. Although the present amount of demand for organic cotton is only 10% of total due to its high price, it is gradually increasing with more concerns about environment.
Cotton originates from India dating back some 5,000 years. Now about 50% of the world’s garments are made in cotton. We feel easy and comfortable wearing cotton because it is made from a natural substance found in plants-cellulose. It has other excellent properties: white color, soft touch, and superior absorbency.
Behind this goodness, however, lies the dark side of cotton farming. Since growing cotton exhausts soil’s nutrients, a lot of chemical fertilizer is used. This type of unnatural nurturing weakens plants against harmful insects. Therefore, pesticides become necessary. Popular demand for cotton textiles has increased the use of pesticide. Cotton is now the most pesticide-dependent crop in the world, accounting for 25% of all pesticide use.
So is your favorite cotton T-shirt full of pesticide? Of course not! Harmful substances are removed and clothes are tested before they are placed in stores. According to FITI, a testing organization, cotton fabric contains less than 0.1% of pesticide. Dye solutions for cotton are also made safe by removing formalin and azo.
Therefore, it is not the degree of safety that organic and non-organic cotton differ in because both have to have almost 0% pesticide to be sold. The true purpose of organic cotton is to save environment. Every year in the United States, 25 million kilograms of pesticide is used. This is polluting water and earth. In order grow organic cotton, not a drop of pesticide should touch the ground for 3 years and natural fertilizers have to be used.
It has been more than 15 years since organic cotton farming started. Although the present amount of demand for organic cotton is only 10% of total due to its high price, it is gradually increasing with more concerns about environment.
Burning Test
If you work with textiles, it is necessary to learn and identify the different types of fibers. But how should you do this? Memorize a book listing every kind of fiber with its property? The answer is obviously no. There is a famous saying by John Dewey:“You learn what you do.”As a strong believer of this doctrine, I recommend you experiment with burning test. You should burn few types of fibers and see how they differ.
When something burns, it is reacting with oxygen. This is called oxidation reaction. Rust on iron is a slow type of oxidation reaction. Breathing is also a form of oxidation reaction. Water and carbohydrates are formed as by- products of glucose burned with oxygen.
Because different types of fiber are made with different substances, each burns with distinctive smell, flame, and ash. It is not necessary to know the burning properties of all existing fiber types. Let’s just take a look at few major ones.
Cotton, the most common type of fiber, is mostly composed of cellulose made from carbon, hydrogen, and oxygen. Cellulose is a substance found in plants. So cotton burns like paper in small and easy flames. It gives off the smell of burning paper and leaves a white ash. If burned slowly, cotton turns into charcoal as the wick in an oil lamp does.
Burning test shows whether the fabric is 100% cotton or blended with other fibers. Warp and weft yarns of the fabric are tested separately. If both burn like paper, the fabric is 100% cotton. A yarn is polyester if it burns quickly with black smoke and forms dark round drops. Synthetic fibers produce black smoke because they are made of polymer compounds with more amount of carbon. Carbon requires a huge amount of oxygen to be burned completely. Due to the lack of oxygen in air, carbon molecules are blown off as black smoke.
Rayon, a type of cellulose fiber, burns like cotton. So it is difficult to identify rayon by burning test. Instead, drapery of fabric is checked. Another way is to look carefully at the fiber, which is longer and glossier than cotton fiber. Rayon-cotton blended fabric, however, is easily distinguished by burning test. Instead of burning in flames and leaving a white ash, it melts and produces grey colored ash. Hemp is another type of cellulose fiber that burns just like cotton. It is impossible to differentiate linen, ramie, and other types of hemp fibers by burning test. Acetate and triacetate are also composed of cellulose but they are distinctive since they burn with black smoke and sour smell.
Wool is also easily identify by burning test. It is made of keratin, the protein found in human hair. In fire, it slowly curls up and produces sulfur smell. The pungent smell makes it easy to identify. Silk also gives off a similar smell when burned. Wool is often blended with acrylic, synthetic fiber that melts in fire. There is a major difference between wool and acrylic when they turn into ash: wool ash crumbles easily whereas acrylic ash remains hard.
Besides acrylic, there are many other types of synthetic fiber like PVC, PU, and PE that show subtle differences in burning test. I stop here because I am not trying to make a textile scientist out of you. What is said above should be enough to get you through your daily work with textiles.
When something burns, it is reacting with oxygen. This is called oxidation reaction. Rust on iron is a slow type of oxidation reaction. Breathing is also a form of oxidation reaction. Water and carbohydrates are formed as by- products of glucose burned with oxygen.
Because different types of fiber are made with different substances, each burns with distinctive smell, flame, and ash. It is not necessary to know the burning properties of all existing fiber types. Let’s just take a look at few major ones.
Cotton, the most common type of fiber, is mostly composed of cellulose made from carbon, hydrogen, and oxygen. Cellulose is a substance found in plants. So cotton burns like paper in small and easy flames. It gives off the smell of burning paper and leaves a white ash. If burned slowly, cotton turns into charcoal as the wick in an oil lamp does.
Burning test shows whether the fabric is 100% cotton or blended with other fibers. Warp and weft yarns of the fabric are tested separately. If both burn like paper, the fabric is 100% cotton. A yarn is polyester if it burns quickly with black smoke and forms dark round drops. Synthetic fibers produce black smoke because they are made of polymer compounds with more amount of carbon. Carbon requires a huge amount of oxygen to be burned completely. Due to the lack of oxygen in air, carbon molecules are blown off as black smoke.
Rayon, a type of cellulose fiber, burns like cotton. So it is difficult to identify rayon by burning test. Instead, drapery of fabric is checked. Another way is to look carefully at the fiber, which is longer and glossier than cotton fiber. Rayon-cotton blended fabric, however, is easily distinguished by burning test. Instead of burning in flames and leaving a white ash, it melts and produces grey colored ash. Hemp is another type of cellulose fiber that burns just like cotton. It is impossible to differentiate linen, ramie, and other types of hemp fibers by burning test. Acetate and triacetate are also composed of cellulose but they are distinctive since they burn with black smoke and sour smell.
Wool is also easily identify by burning test. It is made of keratin, the protein found in human hair. In fire, it slowly curls up and produces sulfur smell. The pungent smell makes it easy to identify. Silk also gives off a similar smell when burned. Wool is often blended with acrylic, synthetic fiber that melts in fire. There is a major difference between wool and acrylic when they turn into ash: wool ash crumbles easily whereas acrylic ash remains hard.
Besides acrylic, there are many other types of synthetic fiber like PVC, PU, and PE that show subtle differences in burning test. I stop here because I am not trying to make a textile scientist out of you. What is said above should be enough to get you through your daily work with textiles.
Colors
Colors are very important for those who work in the textile industry. Managing the consistency of colors in products is a serious matter. What exactly are these colors? What lies beneath the surface of something appearing to be red or blue?
The way the human eye perceives colors is a complicated mechanism, which takes place in the cerebral cortex and the nervous system. Put in a simple way, eyes transmit light to the brain through the optic nerves and the brain analyzes the image. The interesting fact here is that all people perceive the same image differently since the construction their brain and eyes are different with their own distinctive DNA structure. So it is important to understand that each person perceives a color a bit differently, although there is just one color in front of him or her.
What are the principle colors? Sunlight or artificial light is composed of various waves. Classified by the length of each wave, it is composed of electromagnetic wave, infrared ray, visible light, ultraviolet ray, x-ray, and gamma ray. The electromagnetic wave is used for radio, radar, and microwave oven. The wavelength that human eyes can perceive is from 390 nm (nanometers) to 700 nm and it is called visible light.
Human eyes cannot perceive waves with lengths shorter than 390 nm because these waves have very low energy. Waves with lengths beyond 700 nm are invisible because human eyes cannot transmit these. The amount of energy in waves increases as the wavelength shortens. The ultraviolet rays can seriously damage the human body. X-rays can penetrate certain parts of the body and gamma rays can easily penetrate all parts. Gamma rays can disturb the molecular structure of the human body with its high energy. When we look at the sun, more than a billion neutrinos penetrate the body in a second. Fortunately, neutrinos are not harmful because their energy is extremely low.
When a ray of visible light is transmitted through the spectrum, it is divided into seven colors with different wavelength. So when sunlight hits our eyes, optic nerves perceive the wavelength of each color and signal the brain. The shortest wave in visible light is purple and the longest is red. The human eye cannot see the waves beyond these, ultraviolet and infrared.
Visible light waves hit the cornea about 600 billion times each second. Since the velocity of light is 300,000,000cm per second, the wavelength of visible light is be 500 nm.
The frequency for red and purple rays is approximately 460 trillion per second and 760 trillion per second, respectively. Each color has a specific wavelength and frequency. With these exact values of waves called natural frequency, visually impaired would be able to actually feel each color.
Why do human eyes can see only visible light? Each object has different preferred frequency and wavelength of light waves. These take on different colors. Most natural elements on Earth do not absorb visible light. But waves such as gamma rays are absorbed by all elements, including air. Therefore, gamma rays vanish in the air. How fortunate it is! If human eyes could perceive gamma rays or objects on Earth received these rays, all materials would appear black.
A ray of sunlight is mostly visible light. Stars with high temperature radiate mainly ultraviolet rays. Stars with low temperature radiate infrared rays. A black hole radiates x-rays, which allow scientists to detect and confirm their existence.
What does mean for an object to have a specific color? Every object has a specific range of visible light that it can absorb. This determines the object’s color. The color of an object that we see is the complementary color of light that it absorbs. The composition of the reflected light is seen. For an example, a red tomato absorbs the waves near 500 nm that come under green and blue areas of visible light. So it appears red, the complementary color of green and blue. Simply, reflecting blue and green makes a red tomato.
The primary colors are Red, Green and Blue. With these three colors, every other color in nature can be created. The picture on television screen is composed by the three primary colors. It is made of several thousands of very tiny dots in red, green, and blue.
The color of most plants are green because photosynthesis requires red color. The plant’s chlorophylls absorb red waves of sunlight and reflect other colors.
Certain objects reflect sunlight entirely. In this case, the color appears white. On the other hand, objects look black if they absorb all rays of sunlight. If a certain object appears blacker, it has higher rate of absorption. The most blackish object is the black velvet. Velvet reflects only few percentage of visible light due to its piles. However, smooth surface of a black object makes it appear less black by reflecting some colors. A black object with rough surface would not reflect much light and would appear more blackish. The degree of whiteness or blackness is not a matter of color but the percentage of reflection. The brightest white object in the nature is clean snow. But even snow reflects the only 75% visible light.
The reason why the sky looks blue is that the air scatters blue waves invisible light. This is the same reason why ocean is blue. Looking up at the sky from the moon appears black since it has no atmosphere. In Mars, it is red since the planet has a thin atmosphere. Venus has bright blue sky since its atmosphere is 90 times that of Earth. Even on a rainy day, the average temperature of the surface is 480℃.
Chroma measures the purity of color. Chroma value would be high if the level of the absorbed colors is low in the reflected color ray. For instance, pure red should not have blue ray in it. If red is mixed with bluish green, it would appear gray with the purity of red lowered. Color with high chroma looks brighter and color with low chroma looks duller.
Lightness is the index of light level received by the eyes. It is measured from 0 to 10. Lightness of white is 10 and that of black is 0. With hue and chroma fixed, high value in lightness makes the color appear lighter and low value in lightness makes it appear darker.
The reason that dyes show a specific color is due to the chromophoric group in its molecular structure. The chromophore absorbs the specific waves of the spectrum and reflects others. It is connected with the unsaturated double bond of the chromophore and the absorption of the photon. The typical chromophorics are Azo, Azoxy, Nitroso and Quinoid. And auxochrome makes dyes brighter or aids its bondingwith fibers. Sometimes, colors could be changed by auxochrome. Well-known auxochromes are Amine, Alkoxy, Hydroxyl, Sulfone.
The way the human eye perceives colors is a complicated mechanism, which takes place in the cerebral cortex and the nervous system. Put in a simple way, eyes transmit light to the brain through the optic nerves and the brain analyzes the image. The interesting fact here is that all people perceive the same image differently since the construction their brain and eyes are different with their own distinctive DNA structure. So it is important to understand that each person perceives a color a bit differently, although there is just one color in front of him or her.
What are the principle colors? Sunlight or artificial light is composed of various waves. Classified by the length of each wave, it is composed of electromagnetic wave, infrared ray, visible light, ultraviolet ray, x-ray, and gamma ray. The electromagnetic wave is used for radio, radar, and microwave oven. The wavelength that human eyes can perceive is from 390 nm (nanometers) to 700 nm and it is called visible light.
Human eyes cannot perceive waves with lengths shorter than 390 nm because these waves have very low energy. Waves with lengths beyond 700 nm are invisible because human eyes cannot transmit these. The amount of energy in waves increases as the wavelength shortens. The ultraviolet rays can seriously damage the human body. X-rays can penetrate certain parts of the body and gamma rays can easily penetrate all parts. Gamma rays can disturb the molecular structure of the human body with its high energy. When we look at the sun, more than a billion neutrinos penetrate the body in a second. Fortunately, neutrinos are not harmful because their energy is extremely low.
When a ray of visible light is transmitted through the spectrum, it is divided into seven colors with different wavelength. So when sunlight hits our eyes, optic nerves perceive the wavelength of each color and signal the brain. The shortest wave in visible light is purple and the longest is red. The human eye cannot see the waves beyond these, ultraviolet and infrared.
Visible light waves hit the cornea about 600 billion times each second. Since the velocity of light is 300,000,000cm per second, the wavelength of visible light is be 500 nm.
The frequency for red and purple rays is approximately 460 trillion per second and 760 trillion per second, respectively. Each color has a specific wavelength and frequency. With these exact values of waves called natural frequency, visually impaired would be able to actually feel each color.
Why do human eyes can see only visible light? Each object has different preferred frequency and wavelength of light waves. These take on different colors. Most natural elements on Earth do not absorb visible light. But waves such as gamma rays are absorbed by all elements, including air. Therefore, gamma rays vanish in the air. How fortunate it is! If human eyes could perceive gamma rays or objects on Earth received these rays, all materials would appear black.
A ray of sunlight is mostly visible light. Stars with high temperature radiate mainly ultraviolet rays. Stars with low temperature radiate infrared rays. A black hole radiates x-rays, which allow scientists to detect and confirm their existence.
What does mean for an object to have a specific color? Every object has a specific range of visible light that it can absorb. This determines the object’s color. The color of an object that we see is the complementary color of light that it absorbs. The composition of the reflected light is seen. For an example, a red tomato absorbs the waves near 500 nm that come under green and blue areas of visible light. So it appears red, the complementary color of green and blue. Simply, reflecting blue and green makes a red tomato.
The primary colors are Red, Green and Blue. With these three colors, every other color in nature can be created. The picture on television screen is composed by the three primary colors. It is made of several thousands of very tiny dots in red, green, and blue.
The color of most plants are green because photosynthesis requires red color. The plant’s chlorophylls absorb red waves of sunlight and reflect other colors.
Certain objects reflect sunlight entirely. In this case, the color appears white. On the other hand, objects look black if they absorb all rays of sunlight. If a certain object appears blacker, it has higher rate of absorption. The most blackish object is the black velvet. Velvet reflects only few percentage of visible light due to its piles. However, smooth surface of a black object makes it appear less black by reflecting some colors. A black object with rough surface would not reflect much light and would appear more blackish. The degree of whiteness or blackness is not a matter of color but the percentage of reflection. The brightest white object in the nature is clean snow. But even snow reflects the only 75% visible light.
The reason why the sky looks blue is that the air scatters blue waves invisible light. This is the same reason why ocean is blue. Looking up at the sky from the moon appears black since it has no atmosphere. In Mars, it is red since the planet has a thin atmosphere. Venus has bright blue sky since its atmosphere is 90 times that of Earth. Even on a rainy day, the average temperature of the surface is 480℃.
Chroma measures the purity of color. Chroma value would be high if the level of the absorbed colors is low in the reflected color ray. For instance, pure red should not have blue ray in it. If red is mixed with bluish green, it would appear gray with the purity of red lowered. Color with high chroma looks brighter and color with low chroma looks duller.
Lightness is the index of light level received by the eyes. It is measured from 0 to 10. Lightness of white is 10 and that of black is 0. With hue and chroma fixed, high value in lightness makes the color appear lighter and low value in lightness makes it appear darker.
The reason that dyes show a specific color is due to the chromophoric group in its molecular structure. The chromophore absorbs the specific waves of the spectrum and reflects others. It is connected with the unsaturated double bond of the chromophore and the absorption of the photon. The typical chromophorics are Azo, Azoxy, Nitroso and Quinoid. And auxochrome makes dyes brighter or aids its bondingwith fibers. Sometimes, colors could be changed by auxochrome. Well-known auxochromes are Amine, Alkoxy, Hydroxyl, Sulfone.
Yarn Thickness
A merchandiser, let’s call her Kim, in a sourcing office has received a request from her buyer to find a fabric with following specification: cotton chino CM20 × CD16, 120 × 68, 58". Although this is quite a common type of fabric, Kim is confused. She knows what these numbers mean but cannot get a clear picture of this fabric. So she has to call several mills, requesting for cost details and swatches. Kim has no idea about the fabric until the mills respond. And the only way that she can verify the information is through crosschecking with other mills and the buyer. It is a time consuming task. This chapter is about the basics of fabric, yarn count, thickness, and density, which alter its appearance and function.
During my business trip to the States this autumn, I had a free Sunday in my schedule. Not wanting to golf or bother my staff in New York branch office, I decided to go shopping. The place I chose was Woodbury, a very popular outlet that sells top designer brands like Prada, Salvatore Ferragamo, and Gucci. Among its 300 stores, Polo Ralph Lauren was the most crowded.
Polo’s chino pants have been one of its best sellers for more than 20 years. Chino pants are made of cotton twill fabric that Britain once had exported to India and China. Chinos became famous after the American soldiers wore them as uniforms during the First World War. Its name actually means Chinese in Spanish.
The original Chinos seem to have been woven with twisted yarns. Today, Chinos are made from CM20 × OE CD16, 120 × 68 58" fabric. CM stands for combed and CD stands for carded. Both indicate how much the thread has been brushed. The plucked cotton is just a ball of fluff called lap. This is made into a sliver, a rope-like strand. Roving makes cotton into thinner strands and it is the last stage before cotton is spun into a thread. These steps of cotton processing can be described simply-endless brushing. Cotton fibers are scattered in all directions so they need to be aligned. Combing is a more intense version of brushing than carding. The more cotton is combed the finer it becomes.
Cotton fibers are short, about 2.5cm long. These fibers are held together when they are in the form of a lap but become loose as they are combed. In order to spin them into a long thread, the fibers have to be twisted. Finer thread requires more twisting as the force of friction becomes less. The number of twist is proportional to the fineness of yarn. If a yarn gets finer by 4 times, it needs to be twisted twice more. If it gets finer by 9 times, the twisting is thrice more.
If the yarn is twisted more than the above proportion, it becomes shorter and stronger through turning and bending. This type of thread is woven to make fabric with a grainy and uneven surface called crepe. The long chain of 3 billions pairs of DNA nucleotides are placed in tiny cells through this physical aspect of intensified twisting.
The cotton chino fabric has another abbreviation: OE. This stands for open end, a method of yarn spinning that revolutionized the production rate. Sliver skips roving processing and is directly made into a thread. This method, however, is limited to thick yarns with the yarn count less than 16s. The actual limit is 20s, but OE is not usually used for this yarn due to cost inefficiency. The regular method called ring spun (RS) is applied for making finer yarns in 20s and above. Sometimes, RS is used for 16s to make premium denim. OE yarns for 16s and below are cheaper than RS yarns but they are bulky and harder in quality.
The relationship between CM/CD and the yarn count can be explained as above. The limit is 30s. CM is for fine and expensive yarns with yarn count above 30s. CD is for those under 20s. There are some exceptions to this rule for CD 40s and Cm 16s but the limit is kept for cost efficiency. I have never seen other exceptions beside these while working with textiles for 22 years.
Mixing raw cotton is another matter to be concerned about. Cotton varies in its grade according to the length of its fiber. Fine Egyptian cotton is 1cm longer than American cotton. Longer fibers with more friction are spun into longer yarns with less twist and softer touch. So good-grade cotton like Egyptian cotton is used to make finer yarns. It would be nice to make yarns with 100% top-grade cotton but the price has to be kept reasonably high. Raw cotton mixing plays an important role to balance both quality and cost. Yarns in 30s and 40s count have similar price because their cotton mixing proportion is similar. From 50s and on, however, the price suddenly jumps because the proportion of good-grade cotton has to be increased drastically.
In the measurement of chino fabric (CM20 × CD16, 120 × 68, 58inches), 120 × 68 is the scale of density. But what does it really signify? The numbers 120 and 68 indicate there are 120 warps and 68 wefts in one inch or 2.54cm. Since fabric is 58inches in width, the total number of warp is 6960.
Likewise, it is difficult to imagine how thin or thick a yarn is with the numbers of yarn count in 20s and 100s. The numbers are meaningless as 2.5 million light -years. The thickness of a yarn, like a person’s waist, could be measured in circumference but then the number would be too small. So there are two special methods for measuring yarn thickness or yarn count: fixed weight and fixed length.
Fixed weight, or English yarn count, is the most common method used for all types of yarns made of twisted spun fibers. 1s in English yarn count equals to 1 lb of yarn measuring 840yd. So 40s yarn is 1 lb of yarn measuring 33,600 yards in length. So thinner yarn has bigger yarn count number.
The length of 1 lb yarn in 40s is the approximate distance between my home to my office. But how thin is it? 40s yarns are usually used for shirts and rarely for pants because they have weak tearing strength. 30s yarns are made into heavy shirts, light pants, or blankets. Twill pants are made of 20s yarns and canvas fabrics are made of 10s yarns. Sometimes, yarn count is mixed to improve fabric touch. Fabrics with 60/3s yarn count are truly soft although the yarn thickness is equal to 20s. Yarns in 50s and above produce lawn, the fabric used for making fine summer blouses. Cotton woven fabric with the thinnest thread has 100s yarn count. These are used to make high quality lawn, chiffon, and voile.
The other method for measuring yarn count is fixed length method. It is used to measure thickness of filaments in fabrics like polyester, nylon, and silk. The unit is denier: 1d equals 1g per 9,000m. So 9,000 meters of a yarn with 70d is 70g in weight. Unlike English count, yarn gets thicker and heavier with increased denier.
By the way, how is yarn count checked? Complicated equipments are unnecessary. Even a test lab like FITI checks yarn count simply by using a scale and a ruler.
There were two different methods of yarn count for carded wool and combed wool. Combed wool yarn count was the same, 1s equaling 1 lb of 560yd, but carded wool yarn count slightly varied by region. For example, 1s was 1 lb of 256yd in Yorkshire whereas it was 300yds in Philadelphia. These different yarn counts were combined into fixed weight method in the metric unit called Nm. 1 Nm is 1kg of yard in 1km length. The number of yarn count gets higher for finer yarns.
The easiest way to understand Nm count is by converting and comparing it with the English count. Since wool yarn count is about 1.7 times bigger than that of cotton, dividing it by 1.7 results a number that can be compared with cotton yarn count. So when a salesman at a suit says 120s for a suit, the number is actually 70s. For acrylic, 36/2 is the most common yarn count. This is equal to 10s in cotton yarn count.
For synthetic yarn count, 135d equals 40s in cotton yarn count. This is the famous peachskin faille. The most commonly used synthetic fabric has yarn count of 70d for nylon and 75d for polyester. The nylon lining called taffeta has 70d yarn count. 75d polyester comes in CDC, tissue faille, dobby, and GGT used to make blouse. The next common yarn count in synthetic fabric is 150d, which is often combined as weft. Thicker yarn that comes in 150d × 150d or 300d × 300d is moss crepe.
For thinner yarns, 50d/300t is common in nylon used for high density down jacket fabric. 300t here indicates the sum of density in warp and weft. DuPont’s down jacket fabric comes in 40d/330t. With the recent trend for the ultra light fabric, there are fabrics even in 30d and 20d. Mono-filas in 20d are almost as thin as dragonfly wings and have long single threads that look like the strings of a fishing rod.
During my business trip to the States this autumn, I had a free Sunday in my schedule. Not wanting to golf or bother my staff in New York branch office, I decided to go shopping. The place I chose was Woodbury, a very popular outlet that sells top designer brands like Prada, Salvatore Ferragamo, and Gucci. Among its 300 stores, Polo Ralph Lauren was the most crowded.
Polo’s chino pants have been one of its best sellers for more than 20 years. Chino pants are made of cotton twill fabric that Britain once had exported to India and China. Chinos became famous after the American soldiers wore them as uniforms during the First World War. Its name actually means Chinese in Spanish.
The original Chinos seem to have been woven with twisted yarns. Today, Chinos are made from CM20 × OE CD16, 120 × 68 58" fabric. CM stands for combed and CD stands for carded. Both indicate how much the thread has been brushed. The plucked cotton is just a ball of fluff called lap. This is made into a sliver, a rope-like strand. Roving makes cotton into thinner strands and it is the last stage before cotton is spun into a thread. These steps of cotton processing can be described simply-endless brushing. Cotton fibers are scattered in all directions so they need to be aligned. Combing is a more intense version of brushing than carding. The more cotton is combed the finer it becomes.
Cotton fibers are short, about 2.5cm long. These fibers are held together when they are in the form of a lap but become loose as they are combed. In order to spin them into a long thread, the fibers have to be twisted. Finer thread requires more twisting as the force of friction becomes less. The number of twist is proportional to the fineness of yarn. If a yarn gets finer by 4 times, it needs to be twisted twice more. If it gets finer by 9 times, the twisting is thrice more.
If the yarn is twisted more than the above proportion, it becomes shorter and stronger through turning and bending. This type of thread is woven to make fabric with a grainy and uneven surface called crepe. The long chain of 3 billions pairs of DNA nucleotides are placed in tiny cells through this physical aspect of intensified twisting.
The cotton chino fabric has another abbreviation: OE. This stands for open end, a method of yarn spinning that revolutionized the production rate. Sliver skips roving processing and is directly made into a thread. This method, however, is limited to thick yarns with the yarn count less than 16s. The actual limit is 20s, but OE is not usually used for this yarn due to cost inefficiency. The regular method called ring spun (RS) is applied for making finer yarns in 20s and above. Sometimes, RS is used for 16s to make premium denim. OE yarns for 16s and below are cheaper than RS yarns but they are bulky and harder in quality.
The relationship between CM/CD and the yarn count can be explained as above. The limit is 30s. CM is for fine and expensive yarns with yarn count above 30s. CD is for those under 20s. There are some exceptions to this rule for CD 40s and Cm 16s but the limit is kept for cost efficiency. I have never seen other exceptions beside these while working with textiles for 22 years.
Mixing raw cotton is another matter to be concerned about. Cotton varies in its grade according to the length of its fiber. Fine Egyptian cotton is 1cm longer than American cotton. Longer fibers with more friction are spun into longer yarns with less twist and softer touch. So good-grade cotton like Egyptian cotton is used to make finer yarns. It would be nice to make yarns with 100% top-grade cotton but the price has to be kept reasonably high. Raw cotton mixing plays an important role to balance both quality and cost. Yarns in 30s and 40s count have similar price because their cotton mixing proportion is similar. From 50s and on, however, the price suddenly jumps because the proportion of good-grade cotton has to be increased drastically.
In the measurement of chino fabric (CM20 × CD16, 120 × 68, 58inches), 120 × 68 is the scale of density. But what does it really signify? The numbers 120 and 68 indicate there are 120 warps and 68 wefts in one inch or 2.54cm. Since fabric is 58inches in width, the total number of warp is 6960.
Likewise, it is difficult to imagine how thin or thick a yarn is with the numbers of yarn count in 20s and 100s. The numbers are meaningless as 2.5 million light -years. The thickness of a yarn, like a person’s waist, could be measured in circumference but then the number would be too small. So there are two special methods for measuring yarn thickness or yarn count: fixed weight and fixed length.
Fixed weight, or English yarn count, is the most common method used for all types of yarns made of twisted spun fibers. 1s in English yarn count equals to 1 lb of yarn measuring 840yd. So 40s yarn is 1 lb of yarn measuring 33,600 yards in length. So thinner yarn has bigger yarn count number.
The length of 1 lb yarn in 40s is the approximate distance between my home to my office. But how thin is it? 40s yarns are usually used for shirts and rarely for pants because they have weak tearing strength. 30s yarns are made into heavy shirts, light pants, or blankets. Twill pants are made of 20s yarns and canvas fabrics are made of 10s yarns. Sometimes, yarn count is mixed to improve fabric touch. Fabrics with 60/3s yarn count are truly soft although the yarn thickness is equal to 20s. Yarns in 50s and above produce lawn, the fabric used for making fine summer blouses. Cotton woven fabric with the thinnest thread has 100s yarn count. These are used to make high quality lawn, chiffon, and voile.
The other method for measuring yarn count is fixed length method. It is used to measure thickness of filaments in fabrics like polyester, nylon, and silk. The unit is denier: 1d equals 1g per 9,000m. So 9,000 meters of a yarn with 70d is 70g in weight. Unlike English count, yarn gets thicker and heavier with increased denier.
By the way, how is yarn count checked? Complicated equipments are unnecessary. Even a test lab like FITI checks yarn count simply by using a scale and a ruler.
There were two different methods of yarn count for carded wool and combed wool. Combed wool yarn count was the same, 1s equaling 1 lb of 560yd, but carded wool yarn count slightly varied by region. For example, 1s was 1 lb of 256yd in Yorkshire whereas it was 300yds in Philadelphia. These different yarn counts were combined into fixed weight method in the metric unit called Nm. 1 Nm is 1kg of yard in 1km length. The number of yarn count gets higher for finer yarns.
The easiest way to understand Nm count is by converting and comparing it with the English count. Since wool yarn count is about 1.7 times bigger than that of cotton, dividing it by 1.7 results a number that can be compared with cotton yarn count. So when a salesman at a suit says 120s for a suit, the number is actually 70s. For acrylic, 36/2 is the most common yarn count. This is equal to 10s in cotton yarn count.
For synthetic yarn count, 135d equals 40s in cotton yarn count. This is the famous peachskin faille. The most commonly used synthetic fabric has yarn count of 70d for nylon and 75d for polyester. The nylon lining called taffeta has 70d yarn count. 75d polyester comes in CDC, tissue faille, dobby, and GGT used to make blouse. The next common yarn count in synthetic fabric is 150d, which is often combined as weft. Thicker yarn that comes in 150d × 150d or 300d × 300d is moss crepe.
For thinner yarns, 50d/300t is common in nylon used for high density down jacket fabric. 300t here indicates the sum of density in warp and weft. DuPont’s down jacket fabric comes in 40d/330t. With the recent trend for the ultra light fabric, there are fabrics even in 30d and 20d. Mono-filas in 20d are almost as thin as dragonfly wings and have long single threads that look like the strings of a fishing rod.
Fabric Density
Fabric density indicates the number of warp yarns and weft yarns in 1 inch2. For some countries that use the metric system, the area is 1 cm2 and 2.54 is multiplied to convert it into the correct measurement of density. Although many countries use the metric system, the density is almost always measured in inch. It takes more than just a calculation formula to understand what density really means. It is obvious that thicker fabric would have higher density. Density, however, means a lot more than this.
In a piece of fabric, there are two types of density: warp and weft. Warp is always denser than weft because it is more efficient and cheaper to weave fabrics this way. Fabric with 67 inch and 180 warp end count need 12,069 strands of warp yarns (fabric width × warp end count) to be wound. The huge number of warp yarns is no problem because it only requires more creels to be added to the beam. The smaller units of beams with warp yarns come together to form the whole warp beam.
The horizontal weft yarns, on the other hand, require more work. They have to be woven
back and forth. The reciprocal motion requires more time and energy. Most of fabric production is taken up by weaving these weft yarns. The only way to speed up the production is to use a faster weaving machine with higher RPM (revolution per minute).
In the past, looms looked like wooden ships and had maximum 200 RPM. Modern looms are much more efficient. They can work up to 800 RPM. In a buyer’s perspective, however, it may still be too slow. Since the recent trend in fashion is variety, buying a large amount of available fabric is ineffective. Now the demand in market is fresh fabric, woven and dyed quickly in order to be presented immediately at the customers’ request. Time has become the major factor for succeeding in the fashion industry.
Since weft yarns take up most of the production time, decreasing its number will improve speed as much as using a weaving machine with high RPM. Since both manufactures and buyers accept this fact, most fabrics available in market have more warp end count than weft count.
There are exceptions to this rulecorduroy and velveteen. These have more weft yarns than warp yarns because the pile construction requires extra weft yarns in addition to those in its ground. Of course, the number of weft yarns in the ground is less than that of warps yarn.
Fabric density is written out in two ways depending on the type of fabric: grey fabric count and finished fabric count. It is difficult to determine the method used just by looking, so one must inquire the mill to make sure. In case of piece dyed cotton fabric, grey fabric count must be used. The same type of cotton fabric will differ in width after going through the finishing process. It is impossible for factories to control such change. This is why the width is shown in a range, 44/5 or 58/60. The possibility of the change that may occur in the finishing process is taken into consideration.
Even an inch of difference is quite significant in terms of density. A piece of fabric with 45 inch width is stretched 1 inch more than that with 44 inch width. Due to this stretch, about 2.2% density is lost. So there is nothing to be happy about if 44 inch fabric turns out to be 45 inch. Density loss means loss in weight and quality as well. So fabrics made with the same standard need to be marked with the grey fabric count. This will help to identify and compare different fabrics as the same type produced by one factory.
In a mill’s point of view, presenting a bigger number is more advantageous in doing business. So some mills use the finished fabric count for indicating cotton density. There is no lie to this since it is the actual density after all, so they say. But I wonder what a smart customer, who knows the difference between the two count methods, will say about this. If finished fabric count must be used, each roll of fabric has to be indicated with its actual width. Writing down a ranged measurement like 44/5 inch will mislead customers to believe that the fabric has been measured with grey count.
There are other ways that finished fabric count can be misleading. For example, lawn fabric’s grey fabric count is 60 × 60, 90 × 88 44/5 inches. Lawn fabric is always indicated in this measurement, no matter what its actual finished count turns out to be. With finished fabric count, however, it could be marked in 103 × 88 44 inches. This will deceive customers to believe it as a better grade of lawn fabric with higher density. One could even write it as 103 × 75, reasoning there are 13 more warp yarns taken out from weft count. The sum of warp and weft count is the same as the original lawn fabric but it actually is lower in quality. These unusual fabrics completely ignore the optimized standards set by the long history of weaving.
They can cause serious problems like shrinkage and tear when made into garments.
Weft count, on the other hand, is controlled by tension. If strong tension is applied when weaving the fabric, the output quantity gets larger than that of the inputted grey. 1,000 yards of grey fabric can be changed to 1,100 yards by having tension. Some cotton mills in the past took advantage of this to increase production without actually increasing the number of yarns.
They were able to gain extra profit by deceiving buyers and consumers. No one bothered to actually measure the fabric density or investigate this matter further. So it has become a custom for mills to control tension to increase weft count.
There is a type of cotton fabric which cannot be measured in grey fabric countyarn dyed fabric. Yarn dyed fabrics are finished in a specific pattern. The shape of the pattern cannot be affected by the reduction of width. From the very beginning of weaving stage, yarn dyed fabric is designed for the finish. So its density has to follow the measurement of the finished product.
The quality of polyester is determined by weight rather than density. Polyester always becomes heavier and denser in its final stage of production. Moreover, increasing the density of polyester to a certain degree does not make it proportionally heavier. Therefore, polyester is measured in weight. Sometimes, however, density does matter. It is measured with the unit called“T”when comparing a lighter or heavier version to an existing quality. Similarly, density is not an important factor for measuring knit fabric. A piece of knit fabric is stretchable so density or width is meaningless. Instead, it is measured with yarn count and weight.
It is very rare for expensive fabrics show density. They are measured in fiber composition and fabric weight. A piece of woolen fabric has raised surface, so yarn count is of little importance. Weight, however, is an important factor since it indicates the amount of raw material used. Silk is also one of these expensive fabrics that are measured in weight. For worsted fabric, both yarn count and weight are very important factors in determining its quality.
In a piece of fabric, there are two types of density: warp and weft. Warp is always denser than weft because it is more efficient and cheaper to weave fabrics this way. Fabric with 67 inch and 180 warp end count need 12,069 strands of warp yarns (fabric width × warp end count) to be wound. The huge number of warp yarns is no problem because it only requires more creels to be added to the beam. The smaller units of beams with warp yarns come together to form the whole warp beam.
The horizontal weft yarns, on the other hand, require more work. They have to be woven
back and forth. The reciprocal motion requires more time and energy. Most of fabric production is taken up by weaving these weft yarns. The only way to speed up the production is to use a faster weaving machine with higher RPM (revolution per minute).
In the past, looms looked like wooden ships and had maximum 200 RPM. Modern looms are much more efficient. They can work up to 800 RPM. In a buyer’s perspective, however, it may still be too slow. Since the recent trend in fashion is variety, buying a large amount of available fabric is ineffective. Now the demand in market is fresh fabric, woven and dyed quickly in order to be presented immediately at the customers’ request. Time has become the major factor for succeeding in the fashion industry.
Since weft yarns take up most of the production time, decreasing its number will improve speed as much as using a weaving machine with high RPM. Since both manufactures and buyers accept this fact, most fabrics available in market have more warp end count than weft count.
There are exceptions to this rulecorduroy and velveteen. These have more weft yarns than warp yarns because the pile construction requires extra weft yarns in addition to those in its ground. Of course, the number of weft yarns in the ground is less than that of warps yarn.
Fabric density is written out in two ways depending on the type of fabric: grey fabric count and finished fabric count. It is difficult to determine the method used just by looking, so one must inquire the mill to make sure. In case of piece dyed cotton fabric, grey fabric count must be used. The same type of cotton fabric will differ in width after going through the finishing process. It is impossible for factories to control such change. This is why the width is shown in a range, 44/5 or 58/60. The possibility of the change that may occur in the finishing process is taken into consideration.
Even an inch of difference is quite significant in terms of density. A piece of fabric with 45 inch width is stretched 1 inch more than that with 44 inch width. Due to this stretch, about 2.2% density is lost. So there is nothing to be happy about if 44 inch fabric turns out to be 45 inch. Density loss means loss in weight and quality as well. So fabrics made with the same standard need to be marked with the grey fabric count. This will help to identify and compare different fabrics as the same type produced by one factory.
In a mill’s point of view, presenting a bigger number is more advantageous in doing business. So some mills use the finished fabric count for indicating cotton density. There is no lie to this since it is the actual density after all, so they say. But I wonder what a smart customer, who knows the difference between the two count methods, will say about this. If finished fabric count must be used, each roll of fabric has to be indicated with its actual width. Writing down a ranged measurement like 44/5 inch will mislead customers to believe that the fabric has been measured with grey count.
There are other ways that finished fabric count can be misleading. For example, lawn fabric’s grey fabric count is 60 × 60, 90 × 88 44/5 inches. Lawn fabric is always indicated in this measurement, no matter what its actual finished count turns out to be. With finished fabric count, however, it could be marked in 103 × 88 44 inches. This will deceive customers to believe it as a better grade of lawn fabric with higher density. One could even write it as 103 × 75, reasoning there are 13 more warp yarns taken out from weft count. The sum of warp and weft count is the same as the original lawn fabric but it actually is lower in quality. These unusual fabrics completely ignore the optimized standards set by the long history of weaving.
They can cause serious problems like shrinkage and tear when made into garments.
Weft count, on the other hand, is controlled by tension. If strong tension is applied when weaving the fabric, the output quantity gets larger than that of the inputted grey. 1,000 yards of grey fabric can be changed to 1,100 yards by having tension. Some cotton mills in the past took advantage of this to increase production without actually increasing the number of yarns.
They were able to gain extra profit by deceiving buyers and consumers. No one bothered to actually measure the fabric density or investigate this matter further. So it has become a custom for mills to control tension to increase weft count.
There is a type of cotton fabric which cannot be measured in grey fabric countyarn dyed fabric. Yarn dyed fabrics are finished in a specific pattern. The shape of the pattern cannot be affected by the reduction of width. From the very beginning of weaving stage, yarn dyed fabric is designed for the finish. So its density has to follow the measurement of the finished product.
The quality of polyester is determined by weight rather than density. Polyester always becomes heavier and denser in its final stage of production. Moreover, increasing the density of polyester to a certain degree does not make it proportionally heavier. Therefore, polyester is measured in weight. Sometimes, however, density does matter. It is measured with the unit called“T”when comparing a lighter or heavier version to an existing quality. Similarly, density is not an important factor for measuring knit fabric. A piece of knit fabric is stretchable so density or width is meaningless. Instead, it is measured with yarn count and weight.
It is very rare for expensive fabrics show density. They are measured in fiber composition and fabric weight. A piece of woolen fabric has raised surface, so yarn count is of little importance. Weight, however, is an important factor since it indicates the amount of raw material used. Silk is also one of these expensive fabrics that are measured in weight. For worsted fabric, both yarn count and weight are very important factors in determining its quality.
Classification of Textile
Ms. K, who just started working as a merchandiser in a sourcing office, received several fabric cuttings from her buyer. She had to counter source similar fabrics. It was a difficult task for her since she did not have much experience in this field. Specification labels were not available since those swatches were cut out from garment samples that the buyer they bought in Italy or Paris. There were more than 50 mills that she could get help from but the swatches were too small to share with all those mills. She was perplexed with which swatch should go to which mill.
One of the most difficult assignments that merchandisers face is fabric counter sourcing. Experience may help but it is still difficult to figure out who will bring the right fabric quickly among many mills that handle all kinds of fabrics. Even if all swatches were 100% cotton, it cannot be sourced at just one factory because the content is not the only thing that matters when sourcing fabrics. Different factories make yarn dyed fabrics. Denim and corduroy also require special facilities. Producing functional fabrics like stretch requires a factory with long experience. Pang-Rim has new dyeing machines but no know-how for making stretch fabrics.
Before selecting the right mill for the fabric development, understanding the nature of the original fabric comes first. Analyzing fabric is quite easy. Pulling out a strand of weft and warp yarn and burning it helps to identify the content. If the yarn burns like paper with little smoke and white breakable ash, it is cotton. Drapery must be checked to see if the fabric is rayon or modal since burning it alone does not show this. If a certain fabric burns like cotton and has drapery like polyester, it is rayon. Acetate burns with black smoke and leaves hard black with the unique sour smell. If a yarn burns and melts quickly, it is blended. Almost 80% of cotton blended fabric is 65% polyester with 35% cotton. 20% is 50% cotton and 50% polyester.
Labs like FITI check fiber content and yarn count with scale and microscope. It is, however, possible to check these factors without the professional tools. Comparing the unknown yarns with those that have the content and type specified is the easiest way. Untwisting yarns tells whether or not they are ply yarns, which are extremely fine, lustrous, and expensive. Ply yarns have three plies of thread when untwisted. The price for Chinese ply yarns are reasonable. The most common type is the Chinese cavalry twill in 60/3.
The following is an easy way to identify blended fabrics. First, untwist the warp yarn. If it is twisted and burns like paper, it’s cotton. If weft is straight and burns with black smoke and scattered ash, it could be a cotton- nylon, cotton-polyester, or rayon-polyester blend. If the blend contains more than 30% of wool, the development should go to a wool mill. Cotton mills do not have facilities for wool. If the blend contains less than 30% wool, the development should go to an acrylic mill.
Identifying carded or combed yarns from open end yarns can be done by checking out the thickness. Compare yarn strands with others to see the thickness. Carded or combed yarns are usually over 30s and look very fine. Open end yarns are under 20s. There yarns are spun through a simplified process, made directly from slivers. They look rough and uneven.
Spraying a piece of fabric with water is a way to identify water resistant finishing. If water does not get absorbed, the fabric has water resistant coating. If the water gets seeped into fabric in few seconds, the coating is very weak. It probably rates about 70 out of 100. Another way is blowing on the fabric. Air gets blocked if it is coated. The coating gets also streaky when rubbed with an eraser. If the coated fabric feels slippery and wet, it is treated with Silicone. This hand feel is quite similar to micro fiber or silk. It is an expensive processing.
The method to check whether the dyeing material is dyestuff or pigment is to rub fabric on a white paper or fabric. If it gets stained, it is pigment dyed. If you put your sliver on it though it’s sort of dirty, it works better. No wonder with water if it’s available at the moment, as actually wet crocking test is done by this method. Wet crocking is always poorer than dry crocking we know. In case of Denim, this method is applied to check if it’s Indigo or just dyed with reactive dye stuff.
The names of cotton fabric being sold a lot recently are Canvas, Bedford cord, Calico, Sheeting, Shirting, Bengaline, Oxford, Drill, Poplin, Pique etc. Canvas is the canvas a painter draws on. Normally it’s 10 × 10, 65 × 42 and recent China quality is slightly transformed with more density in warp that is 70 × 42. If replacing 10s of warp and weft with 20/2, as mentioned before, quality gets up thanks to ply yarn. Recent along with popularity of Canvas, in fact they are not Canvas but just Poplin which is 20s or even 30s are sold as the name of Light Canvas. It’s kind of marketing strategy. Therefore I think that fabric classification by its name gets insignificant. It seems like that if they are slightly heavier plain cotton, they are called as Canvas roughly, also kind of marketing stretagy. It’s not only in textile field this kind of naming all with popular one. Nano technology is one of them. There are lots of cases that in fact they are not real nano size but named 10 nano or 100 nano etc. By their way, my finger is nano by ten million nano. I mean we don’t need to stick on each name of fabric. There are quite cases that buyers are using without knowing exactly, so we might waste time with searching for an incorrect stuff.
Bedford cord is a fabric having cord like Corduroy though not a real pile. It’s normally 16 wale size cord. Wale is a number of cords in one inch, 2.54cm. We don’t count wale of Bedford cord. It is used along with calling Pique though they are strictly speaking different. But lots of cases both are called at once, so I feel you can say Pique looks like Bedford cord.
Sheeting is recently not used a lot but in the past it was popular as much as it took more than half of cotton consumption. It is called as Calico and it’s 20 × 20, 60 × 60 plain weave.
A lighter version of sheeting is shirting, 30 × 30, 68 × 68. Both are different in weight but were at similar price ranges. Shirting is used a lot by now for cheap cotton prints. It’s loose density-wise and not a combed cotton but after printing on it, if doing so called Schreiner finish that is a gloss finish sort of Chintz, it looks cool. It is used a lot for bed sheet or covers.
Poplin is one of popular shirt fabric and it’s 40 × 40, 133 × 72. Actually it’s the most used cotton shirts. After Spandex came out, women shirts came out in stretch mainly. It’s good for print vehicle. In the past most of men’s dress shirts was 186T which is 45 × 45, 110 × 76 T/C though now almost were replaced with cotton shirts.
Oxford is warp and weft are parallel and expensive shirting fabric but recently its range gets wider and some time used for outwear material in heavy weaving. Originally Oxford is parallel weave in both warp and weft but nowadays it’s mixed with Duck which is only warp in parallel. Polo’s oxford is famous. Drill is heavy twill fabric. Chino being famous for Polo pants is 20 × 16, 126 × 58 and if using more than 10s for Chino is Drill. And recently there is Broken Twill gets popular due to too much chino twill. Broken Twill comes in Denim quite a lot and it looks like half done HBT(Herring Bone Twill). HBT became famous for shoulder uniform. Basically the weaving looks like a bone of Herring, so it was named after the shape, interesting.
Satin is what weft goes beneath and only warp appears on the face, so it’s easy to get snagged, so brushing could cover this weak point. Especially Mole skin or Suede should be based on Satin weave. Mole skin and Suede looks like simple items but in fact they are picky and difficult, so there are only several factories which can treat with them correctly, so prices are high. If doing China quality for cheap price, there could be more tuition for hard quality control.
Pique is the pique from Lacoste knit but in woven item, pique is used along with Bedford cord as the same name. Honeycomb texture which looks like waffle is a kind of pique and it had totally different back and face.
There is a fabric called Bird’s eye. This is basket weave and if you look at closely, it shows 4 warps and 1 weft of plain weave. It looks as if basket shape.
One of the most difficult assignments that merchandisers face is fabric counter sourcing. Experience may help but it is still difficult to figure out who will bring the right fabric quickly among many mills that handle all kinds of fabrics. Even if all swatches were 100% cotton, it cannot be sourced at just one factory because the content is not the only thing that matters when sourcing fabrics. Different factories make yarn dyed fabrics. Denim and corduroy also require special facilities. Producing functional fabrics like stretch requires a factory with long experience. Pang-Rim has new dyeing machines but no know-how for making stretch fabrics.
Before selecting the right mill for the fabric development, understanding the nature of the original fabric comes first. Analyzing fabric is quite easy. Pulling out a strand of weft and warp yarn and burning it helps to identify the content. If the yarn burns like paper with little smoke and white breakable ash, it is cotton. Drapery must be checked to see if the fabric is rayon or modal since burning it alone does not show this. If a certain fabric burns like cotton and has drapery like polyester, it is rayon. Acetate burns with black smoke and leaves hard black with the unique sour smell. If a yarn burns and melts quickly, it is blended. Almost 80% of cotton blended fabric is 65% polyester with 35% cotton. 20% is 50% cotton and 50% polyester.
Labs like FITI check fiber content and yarn count with scale and microscope. It is, however, possible to check these factors without the professional tools. Comparing the unknown yarns with those that have the content and type specified is the easiest way. Untwisting yarns tells whether or not they are ply yarns, which are extremely fine, lustrous, and expensive. Ply yarns have three plies of thread when untwisted. The price for Chinese ply yarns are reasonable. The most common type is the Chinese cavalry twill in 60/3.
The following is an easy way to identify blended fabrics. First, untwist the warp yarn. If it is twisted and burns like paper, it’s cotton. If weft is straight and burns with black smoke and scattered ash, it could be a cotton- nylon, cotton-polyester, or rayon-polyester blend. If the blend contains more than 30% of wool, the development should go to a wool mill. Cotton mills do not have facilities for wool. If the blend contains less than 30% wool, the development should go to an acrylic mill.
Identifying carded or combed yarns from open end yarns can be done by checking out the thickness. Compare yarn strands with others to see the thickness. Carded or combed yarns are usually over 30s and look very fine. Open end yarns are under 20s. There yarns are spun through a simplified process, made directly from slivers. They look rough and uneven.
Spraying a piece of fabric with water is a way to identify water resistant finishing. If water does not get absorbed, the fabric has water resistant coating. If the water gets seeped into fabric in few seconds, the coating is very weak. It probably rates about 70 out of 100. Another way is blowing on the fabric. Air gets blocked if it is coated. The coating gets also streaky when rubbed with an eraser. If the coated fabric feels slippery and wet, it is treated with Silicone. This hand feel is quite similar to micro fiber or silk. It is an expensive processing.
The method to check whether the dyeing material is dyestuff or pigment is to rub fabric on a white paper or fabric. If it gets stained, it is pigment dyed. If you put your sliver on it though it’s sort of dirty, it works better. No wonder with water if it’s available at the moment, as actually wet crocking test is done by this method. Wet crocking is always poorer than dry crocking we know. In case of Denim, this method is applied to check if it’s Indigo or just dyed with reactive dye stuff.
The names of cotton fabric being sold a lot recently are Canvas, Bedford cord, Calico, Sheeting, Shirting, Bengaline, Oxford, Drill, Poplin, Pique etc. Canvas is the canvas a painter draws on. Normally it’s 10 × 10, 65 × 42 and recent China quality is slightly transformed with more density in warp that is 70 × 42. If replacing 10s of warp and weft with 20/2, as mentioned before, quality gets up thanks to ply yarn. Recent along with popularity of Canvas, in fact they are not Canvas but just Poplin which is 20s or even 30s are sold as the name of Light Canvas. It’s kind of marketing strategy. Therefore I think that fabric classification by its name gets insignificant. It seems like that if they are slightly heavier plain cotton, they are called as Canvas roughly, also kind of marketing stretagy. It’s not only in textile field this kind of naming all with popular one. Nano technology is one of them. There are lots of cases that in fact they are not real nano size but named 10 nano or 100 nano etc. By their way, my finger is nano by ten million nano. I mean we don’t need to stick on each name of fabric. There are quite cases that buyers are using without knowing exactly, so we might waste time with searching for an incorrect stuff.
Bedford cord is a fabric having cord like Corduroy though not a real pile. It’s normally 16 wale size cord. Wale is a number of cords in one inch, 2.54cm. We don’t count wale of Bedford cord. It is used along with calling Pique though they are strictly speaking different. But lots of cases both are called at once, so I feel you can say Pique looks like Bedford cord.Sheeting is recently not used a lot but in the past it was popular as much as it took more than half of cotton consumption. It is called as Calico and it’s 20 × 20, 60 × 60 plain weave.
A lighter version of sheeting is shirting, 30 × 30, 68 × 68. Both are different in weight but were at similar price ranges. Shirting is used a lot by now for cheap cotton prints. It’s loose density-wise and not a combed cotton but after printing on it, if doing so called Schreiner finish that is a gloss finish sort of Chintz, it looks cool. It is used a lot for bed sheet or covers.
Poplin is one of popular shirt fabric and it’s 40 × 40, 133 × 72. Actually it’s the most used cotton shirts. After Spandex came out, women shirts came out in stretch mainly. It’s good for print vehicle. In the past most of men’s dress shirts was 186T which is 45 × 45, 110 × 76 T/C though now almost were replaced with cotton shirts.
Oxford is warp and weft are parallel and expensive shirting fabric but recently its range gets wider and some time used for outwear material in heavy weaving. Originally Oxford is parallel weave in both warp and weft but nowadays it’s mixed with Duck which is only warp in parallel. Polo’s oxford is famous. Drill is heavy twill fabric. Chino being famous for Polo pants is 20 × 16, 126 × 58 and if using more than 10s for Chino is Drill. And recently there is Broken Twill gets popular due to too much chino twill. Broken Twill comes in Denim quite a lot and it looks like half done HBT(Herring Bone Twill). HBT became famous for shoulder uniform. Basically the weaving looks like a bone of Herring, so it was named after the shape, interesting.
Satin is what weft goes beneath and only warp appears on the face, so it’s easy to get snagged, so brushing could cover this weak point. Especially Mole skin or Suede should be based on Satin weave. Mole skin and Suede looks like simple items but in fact they are picky and difficult, so there are only several factories which can treat with them correctly, so prices are high. If doing China quality for cheap price, there could be more tuition for hard quality control.
Pique is the pique from Lacoste knit but in woven item, pique is used along with Bedford cord as the same name. Honeycomb texture which looks like waffle is a kind of pique and it had totally different back and face.
There is a fabric called Bird’s eye. This is basket weave and if you look at closely, it shows 4 warps and 1 weft of plain weave. It looks as if basket shape.
Bengaline is a heavy fabric of plain weave with thick yarn such as 10s or 7s in weft, so it forms ridge in weft direction. Warp does hardly appear. Ottoman is a fabric of which face shows ridge one by one but recently both ottoman and bengaline are used at once, so you don’t need to tell them apart clearly.
Crepon is yoryu. Yoryu is the fabric having high twists in weft. Therefore it forms wave in warp direction. Mainly Rayon came out as yoryu quite a lot, but recently other fabrics frequently comes out in yoryu. 30 × 24, 68 × 44 are the original spec.
Velveteen and velvet looks quite similar but source of them is totally different. Velveteen is produced by Corduroy factory but Velvet is not manufactured by the factory making Corduroy. Velvet is made by totally different machine I’d like to remind you. This kind of confusion happens in Yarn dyed as well. Yarn dyed factory are dealing with mainly cotton, T/C and recently union fabric and that’s all and Corduroy is done by special manufacturer. So if you get yarn dyed corduroy, you feel lost the way to ask. But in this case though rare, you should go to Corduroy factory. Surely yarn dyed corduroy is not mainly dealt by many factories. Corduroy manufacturer doesn’t have yarn dyed facility, so he should buy dyed yarn from outside. Therefore if encountering troubles with this kind of fabric, appropriate measure is way too far, so it’s better go around this kind of troublesome item. In case of Linen in yarn dyed item, it’s not doable in general cotton manufacturer and we should find a factory specialized for Linen Yarn dyed goods. But if it’s solid, most of cotton dyeing factories are dealing with linen as linen is also cellulose fiber like cotton, so it reacts with reactive dye stuff.
Jacquard is popular, small pattern for example Pique is doable by Dobby weaving machine but the bigger pattern is to be done by Jacquard machine, so no matter what it’s cotton or systhetic, Jacquard should be produced by jacquard specialized factory. Recent cotton Jacquard factory except for Korea domestic markets disappeared and it’s not easy to find in China either. But synthetic Jacquard is easily seen in both polyester and union fabric. The border line between Dobby and Jacquard is the number of warp, if it’s more than 8, it’s Jacquard.
The next is wool. Once facing wool, initially you should tell apart worsted from woolen wool. Worsted wool is used for suits that is not that heavy so it’s easily distinguished but sometime like Tweed, there are several woolen wools which look like worsted one. About 99% of worsted wool is used for mans suits. As there are a few processing on the fabric, we can say that it’s quite easy to classify worsted or woolen wool.
Worsted wool has quite similar appearance to blended wool, pure wool and T/R which recently look almost like worsted wool, so it requires careful attention to tell them apart. (In fact fake wool, T/R is so great that it’s hard even for specialist to tell apart.) The method is yes to burn. Pure wool smells like hair burning and leaves no hard ash as it’s protein like silk. Blended wool smells like hair burning but leave debris that doesn’t easily break. T/R burns without smell of hair burning. And the difference of them is that worsted wool is not readily wrinkled and if it’s wrinkled, it’s flattened in a day but T/R gets crinkled easily and hardly recovered. Therefore Rayon would be better put less and Polyester more as much as possible in order to prevent wrinkles.
Woolen wool which is used for winter coat a lot has several types. Those types, weight and composition is the factors you should know to calculate the net price which is unlike cotton of which price is dependent on density and yarn count. The type of Woolen wool is determined by the length of hair and shape. Most of all are brushed so that the grounds are not seen. Melton which is used for baseball jumper the most looks like Felt which is non woven but packed sheet. So Melton is heavier than its thickness. This is the cheapest wool when comparing per weight. This is thin but weight is high so wool content tends to be low.
On the contrary to Melton, Mossa has short hair which is raised, the most common type. Beaver has slightly longer hair than Mossa. You know the beaver, think about the shape of hair when a beaver wet. There is longer hair than Beaver that is Cashmere type, very luxury 
fabric. Mostly it contains at least 80% of wool. Of course it’s not a real cashmere but looks like cashmere. Beaver is in fact rare and it’s presented when the cheaper one than cashmere is required.
There is transformed Mossa that is cut hair shorter than Mossa and it’s kind of luxury fabric. This type is called“Velour”. Mostly it contains more than 90% of wool and it’s consumed domestically in Korea. Don’t confuse with knit velvet, Velour.
The thinnest and cheapest wool is Flannel, the only shirting item among woolen wool. Recently there came out the quality version called“Highmere”.
Recently the longer hair than cashmere came out that is Alpaca. In fact Alpaca is contained by 15-30% only because it’s expensive. Mohair is a wool fiber which is long, curl and lust. The thing important is that only Alpaca and Mohair is a name of material and the others are types by finishing and the kind of wool of those are called Merino.
The woolen wool which has different face and back is of course double weave and they are to be separated by two sheets. Mostly they weigh more than 20oz for coat purpose. Most black and white so overall looking like grey is Chambray type of classical plain that is Homespun. There are lots of naps which look like sugar grains on the fabric face and those naps gives multi colors. It was so trend along with HBT recently. Angora comes from rabbit unlike other wool fibers which come from ram or lama.
There are two types of wool portion in woolen wool. First is Virgin wool and the other is recycled wool. Virgin wool is produced at the first and the opposite notion to recycle wool. It has high wool contents and luxury goods are woven with mostly Virgin wool. Cheap wool containing less than 50% of wool such as Melton will be probably woven with recycled one.
Generally others of woolen wool fabrics are Acryl, Nylon or Polyester and the amount of each depends on colors. Therefore each composition is marked as Others without distinguishing each. In China where synthetic fibers are short, others are mostly filled with Rayon, and the problem of this high rayon content is that wrinkle gets easily, however customer is hardly able to notice if it’s more wrinkled, I think. Telling apart recycled wool from virgin wool is in fact impossible but only in the country where recycled wool is not strictly controlled such as China or India, the woolen wool composition could be incorrect because of synthetic fibers that could mix into recycled wool.
Like in the relationship between worsted wool and T/R, in the relationship between Acrylic and woolen wool, there is few who can distinguish woolen wool from Acrylic. Acrylic is what we feel the cabin blanket tending to generate static electricity and pilling a lot. A long hair by heavy brush tends to pilling. We can check Acrylic and woolen wool by burning. Acrylic melt with bubble boiling and smoke, it leaves hard ash. Acrylic is used along with wool in quite similar appearance in knit and sweater, so it is confused with wool but in woven, acrylic is limited to be adopted, so it’s not often you should face the case to recognize.
Micro is graded by fiber fineness. The finer the fiber is, the more expensive and 
better it is. In the past the price differed quite a lot by fiber fineness but recently it doesn’t. If you feel its unique softness by buffing when touching, it is what having finer fiber. Normally it starts low 0.8d to 0.1d which is good quality. You can grade micro fiber by checking composition carefully. It’s because that in order to keep the fineness of fiber to the degree of 0.3d, the fiber should be split fiber or Sea Island fiber and it is not doable with 100% polyester. Therefore micro containing some nylon is a good quality. However there are several fake which is N/P in warp and weft with taking advantage of such fact they play as if they are real micro. The real one is what containing less then 15% of nylon.
Recently the most wonderful hand feel of micro is N/P/C union which is the most 
expensive micro fiber. It has unique hand feel that is softly wet and as if pleasantly covering you. In fact the micro touch came at the first time by silk sand wash which was sensationally great hand feel. Someone disregarded the care label for a silk blouse and crunched it into water to wash and then it was rubbed to sandy so the hand feel unexpectedly became so exotic which was they never met before, and it was not a long time for people to be charmed by it. The buffing hand feel of micro fiber has been stimulating people’s emotion since it was borne 15 years ago. Did you touch teddy bear recently? It became to have softer feeling than mink’s fur rather than a real bear once Acrylic Boa of teddy bear fur was replaced with Micro Boa. I think this trend will go on for a while.
Textile Science
Cars need fuel to run. Likewise, everything requires fuel to be sustained. Cows need to chew and regurgitate grass endlessly to sustain their huge bodies. Human beings eat food three times a day in order to secure enough energy for living. This fuel is glucose, a type of sugar. It is a common source of energy for all animals and plants. Everything starts from the sun. Carbon, hydrogen, oxygen, and 92 other key elements all originate from the sun. It provides energy to Earth from 150 million kilometers away with energy generated from nuclear fusion reactions. These happen when 597 million tons of hydrogen is combined to create 593 million tons of helium. The difference in masses converts into energy. This is the energy source for 50 millions of species on Earth. It was not until the 20th century that mankind attempted to harness the solar energy to generate electricity. Plants, however, have been already converting the solar energy 3,600 million years ago through a chemical process called photosynthesis.
Countless plants depend on the energy from the sun. Plants produce 180 grams of glucose from 688 Kcal of solar energy. 6 moles of carbon dioxide and 6 moles of water and 6 moles of oxygen are also produced. A mole is Avogadro’s number, 6×1023. Glucose that consists of carbon, hydrogen, and oxygen is called carbohydrate. Plants convert some glucose to starch for immediate use. The rest is stored in insoluble state. In this process, glucose becomes a linear-chained molecule called polymer. This is also called fiber. Polymer goes through a chemical reaction that joins chains of polymers called polymerization. The human DNA is a type of polymer with four types of protein: adenine, thymine, guanine and cytosine. Protein is made of 20 kinds of polymerized amino acids.
The polymer which plants change into glucose is called cellulose, the source of plants structure. The fuel for animals is also glucose. Animals, however, cannot photosynthesize. Therefore, they either gain it from plants or other animals. As the result of evolution of plants’ defense mechanism, animals cannot digest cellulous. Starch, the form of sugar stored in plants, is fortunately digestible. Starch is turned into disaccharide (two glucose units) by ptyalin, an enzyme in saliva that unchains the polymers. Fully digested glucose in stomach is turned into monosaccharide. Cellulose is a polysaccharide containing 2,500 to 10,000 glucose molecules. Polysaccharide is a form of sugar but its taste is not sweet. Reducing the number of glucose molecules to about 2 makes sweet tasting sugar types called fructose and sucrose. Cellulose and starch are glucose polymers. The cellulose structure of natural fibers plays an important role in determining their properties. Cotton is 99% cellulose made of 3 basic elements: carbon, hydrogen, and oxygen. Burning cotton smells like paper and it is turned into black ash. Cellulose becomes partially crystallized during polymerization. Its amorphous portion makes it become wrinkled. Synthetic fabric like polyester does not become creased easily because the fiber is mostly crystalline in structure.
Hemp is a polymer made of cellulose and pectin which contains about 36,000 glucose molecules. It is tougher than cotton but becomes easily wrinkled because its cellulose structure is more amorphous than that of cotton. Hemp is characterized by its high thermal conductivity, which makes it feel cool. It is good for making summer clothes.
Based on the notion that plants are generally made of cellulose, there has been an attempt to obtain cotton from wood in England. It is true that wood pulp mostly consists of cellulose. Wood cellulose, however, is too entangled to be made into fibers. Its proper use is making paper through grinding and flattening cellulose.
If cellulose is melted, it can be made into fibers by passing the liquid through a noz
zle. This method was developed by Courtaulds, a mill in England. Cellulose was turned into sticky brown syrup by adding sodium hydroxide and carbon disulfide. The yarn that came out of the nozzle was viscose rayon. Making the solution into a thin paper-like shape makes it cellophane. If it is shaped into a ball, it becomes a ping-pong ball. Viscose is the same with cotton in composition as we can check by the smell that both smells same when burning. But the former is likely to crease more and less strong than cotton due to less crystallization portion.
If cellulose is melted, it can be made into fibers by passing the liquid through a noz
zle. This method was developed by Courtaulds, a mill in England. Cellulose was turned into sticky brown syrup by adding sodium hydroxide and carbon disulfide. The yarn that came out of the nozzle was viscose rayon. Making the solution into a thin paper-like shape makes it cellophane. If it is shaped into a ball, it becomes a ping-pong ball. Viscose is the same with cotton in composition as we can check by the smell that both smells same when burning. But the former is likely to crease more and less strong than cotton due to less crystallization portion. Viscose was once popular because it felt and looked like silk. Its popularity declined due to pollution caused by toxic solvents used in its production. The next cellulose based fiber was modal, developed by Lenzing in Austria. It was better than rayon with more strength that allowed additional finishing effects like sandwash. The new cellulose based fiber, however, still did not completely solve the pollution problem. This defect would eventually lead to the development of Tencel fibers.
Rayon must be the most well-known artificial fiber that is made from cellulose. It is also called bemberg, which is also the name of the company that developed it. The fiber is spun from lint solvent, not wood pulp. Copper ammonia is used to melt the lints. Rayon is also called cupra-ammonium rayon after this chemical.
Viscose and rayon are mixed sometimes. Viscose rayon is actually closer to viscose because it retains more of the cellulose characteristic similar to viscose. Rayon is mixed with acetate to be made into acetate rayon, which behaves more like a synthetic fiber. It also burns like polyester, producing black smoke. Viscose rayon and acetate rayon are both made with acetic acid solvent. Occasionally, acetate rayon accidently changes to viscose through the process of saponification. This is explained in more detail in "Acetate and Viscose."
Where as cellulose is made of glucose polymers, protein is polymerized
with tiny molecules called amino acids. There are 20 different types of amino acids that make up this building block of life. Some names of amino acids are glycine, glutamine, and lysine. These may all sound familiar to the fanatic readers of Jurassic Park. Protein is truly the building block of animal cells. Hemoglobin that transfers oxygen in human body is a type of protein made with 580 amino acid. Wool and silk are made of protein as well. Because amino acids that make up protein contain sulfur and nitrogen, burning animal cells smells like sulfur.As cellulose based fiber has been artificially created in the lab as rayon, protein fiber also has gone through this development. Human desire to mimic nature's power just seems endless. Wallace Hume Carothers synthesized a high polymer with two molecules, adipic acid and hexamethylenediamine. This is nylon, which has a similar chemical structure as that of the peptide bond in protein. For this reason, rayon is called amide or poly amide. The proto type of nylon is 66 nylon made of two molecules, adipic acid and hexamethylenediamine with 6 carbons. Nylon 6 comes after, with its production simplified by requiring polymerization of only one type of molecule called caprolactam. Nylon is similar to animal fiber because it has nitrogen and amine groups of amino acid which are not found in cellulose based fibers. Due to its high thermal conductivity that makes it lose heat fast, different types of nylon has been developed by blending the fiber with cotton.
Polyester taking up 65% of synthetic fiber production is a high polymer created from ethylene glycol and terephthalic acid. Its name comes from esterification, the reaction between alcohol and acid. Polyester is more popular than nylon because it is easy to print on and is weight reducible. Polyester is a compound of carbon, hydrogen, and oxygen like cotton. Although the chemical composition is similar, polyester does not decompose like cotton. It takes 500 years to become fully decomposed.
Unlike other synthetic fibers that have been made to be like silk, acrylic is an alternative to wool. Acrylic is made in fibers rather than filaments. It is made by vinyl polymerization, similar to the way PVC and PVA are produced. As it contains nitrogen, its behavior is like that of an animal fiber. Because of this nitrogen in its chemical structure, another name for acrylic is acrylonitrile. Ironically, acrylic belongs to the chemical family of potassium cyanide that Wallace Hume Carothers put into his orange juice to commit suicide.
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