Friday, March 26, 2010

My textiles class is finally finished with fibers. We are beginning yarns in lecture, and in lab we already covered yarns and are now moving on to woven fabrics. Our first task was to use magnifying glasses to examine fabric samples and identify the weave. We then had to diagram some weaves.
I had no trouble with plain and basket weaves. Twill weaves were a confusing, but after I started to draw a diagram they became a bit easier. Satin weaves had me stymied. I read about satin weaves in my textbook, I looked at diagrams, and I used a stereoscopic microscope to examine some fabric, but I still did not understand the weave. Fortunately I had one more task to perform for the lab, and it was that last task that finally allowed me to understand satin weaves.

I do not know if my school has a loom, but we did not need one to construct weaves. We wove strips of construction paper. At first it felt like a silly assignment. As I constructed a plan and basket weave I thought this would be a good art project for kindergarten students, but for college students it seemed a little demeaning.

As I moved on to a twill weave I began to understand the value of this project. Twill quickly went from slightly confusing to very easy.

Then there was satin. As I began to weave my strips of paper together I still had no understanding of the weave. It took me a few tries to get the piece started, but once I made it to my fourth correctly inserted filling “yarn” I finally had a basic understanding of the weave.

Satin still is not easy, but at least I now understand how it works. This silly assignment turned out to be quite useful in teaching me about various weaves. Next week we will look at fancy and novelty weaves. Oy vey. I need to go buy some construction paper to play with at home.

Friday, March 19, 2010

Skirt - 3rd time's the charm

I apologize for allowing so much time to pass since my last post. In the week before spring break I have been overwhelmed with tests and papers. But now spring break has begun and I can spend time on important stuff such as making a few shirts for myself and writing blog entries.
My apparel construction class has begun work on pants; our skirts were finished a week ago. It took me three attempts to make a skirt, but I am quite pleased with the finished product. There were problems with the seam finishes on my first skirt. I could have torn out the stitching, but I had enough fabric and time to start over. Skirt number two was going well, but at some point between one class and the next the fabric got stretched. Where the skirt used to hug the mannequin’s curves nicely it now has an unsightly bulge. I tried to steam it out, but I could not shrink the fabric enough. I was not happy about this, but I wanted a good grade so I started my third skirt.
I chose a different fabric for the third skirt in hopes of avoiding another unfortunate stretching incident. The first two skirts were a cotton/rayon blend. The skirt was made for a mannequin, not a person, so I did not care if it is dry-clean only. I chose the fabric for its print, weight, and price. I used 100% cotton denim for my third skirt. I wanted a fabric I could trust.

I learned the pattern’s idiosyncrasies on skirts one and two, so skirt number three was easy. The only bit I found at all troublesome was the hem. I was required to hand stitch the hem, and I had no hand stitching experience. I now know how to hem a skirt without the aid of modern technology. I do not like hand stitching, and I do not intend to use it too often, but it is always good to learn new skills.

I got an A for the skirt. My instructor pointed out that the side seams do not line up perfectly with the line of my model’s legs, but it was close. She acknowledged that it is easier to get a close fit on real people, so I did not lose any points for that. I was a little upset that she did not have any comments about my seam finishes. There was no requirement for a specific type of seam finish as long as there were no exposed unfinished edges. The rest of the class used sergers to finish their seams. I do not like the look of serged seam finishes, so I made flat felled seams. It is my favorite seam and the most appropriate one for denim.

I considered making a skirt for myself instead of for the mannequin. It would have been fun to wear a skirt in class for the final fitting, but I decided it would be better to make one for a woman’s body. I do not have curves in the right places. There is not much demand for men’s skirts, so I thought it would be wise to learn to learn women’s skirts first.

Tuesday, March 9, 2010

Disregarding care labels

I recently completed a small project about label laws for my textiles class. As part of the project I had to examine the labels from a garment made of two or more types of fiber. I needed to explain what the information on the labels means. I also had to assess the care instructions to determine if they are appropriate.

A brief search of my closet turned up some shirts, a sweater, and two pairs of bicycle shorts that met the fiber requirements for the project. The shorts contained some synthetic fibers I have not learned about yet, so I did not use them. The sweater had the most interesting combination of fibers. It contains cotton, acrylic, and two other synthetic fibers, but I was unable to use it. I have never washed the sweater, so I cannot comment on its care instructions. No, I do not have a dirty sweater in my closet. It has never been washed because it has never been worn. That left me with a choice between a cotton/rayon shirt and a cotton/polyester shirt. Both have been worn and washed a lot, but only the cotton/poly shirt has been ironed, so that is the one I chose. Had I picked the cotton/rayon one my responses would have looked the same. I have not followed the care instructions for either one.

Care instruction labels never attracted my attention before this semester. I knew to separate whites and darks, and to not use the higher iron temperatures on synthetic fabrics, but I never considered a temperature setting other than high for a washing machine. For white shirts I set dryers at medium temperatures, but for all other items I used the highest dryer temperature setting. In the Laundromat dryers 12 minutes at high heat costs the same as 12 minutes on low heat. Other than a few white shirts that were slightly singed by dryers on high and one olefin carpet that should not have been ironed, none of my textile products have been damaged by my care. (Ink stains from pens left in pants pockets in the wash don’t count.)

The care labels for both shirts advise me to wash cold, dry low, iron warm, and use only non-chlorine bleach. The cotton/rayon shirt is dark blue, so I do not bleach it, but the white cotton/poly shirt is always washed with a large dose of chlorine bleach. The cotton/rayon shirt is dried at high heat, and the cotton/poly at medium. Both shirts are washed at high heat. My iron is set near its highest setting for the cotton/poly shirt. Neither shirt has suffered any damage from my aggressive care.

It seems to me that care labels are overly restrictive. I found labels recommending low heat settings for 100% cotton shirts and pants. Before taking my textiles class I did not know that rayon is easily damaged by heat, yet my two 100% rayon shirts have survived multiple hot washings without harm. I treat my dry-clean-only garments correctly, but why must I treat my machine-washable items so gently? I suspect manufacturers exhort us to exercise such caution in how we wash our garments in order to avoid responsibility for the routine wear and tear that garments experience. I will continue to disregard most care labels, and I will accept the blame for any damage to my clothing in the wash.

Tuesday, March 2, 2010

Textiles review: manufactured regenerated fibers

The final part of my textiles review covers regenerated fibers. I imagine my textiles reviews are not as exciting to read as are my normal blog entries, but writing them was quite helpful to me. The test was yesterday. I found it easy. I am sorry if you do not care for these reviews, but I plan to write more of them next time a test rolls around. Fortunately that will not be for a while, so I may now return to my normal irreverent blogging.

Manufactured fibers are formed into fibers from chemical compounds. They do not exist in fiber form without human intervention. Manufactured fibers may be regenerated or synthetic. Regenerated fibers are produced from naturally occurring polymers that do not occur naturally as fibers. Regenerated fibers are made from cellulose (plant) or protein (plant or animal). Synthetic fibers are made from polymers that do not occur naturally.

The Federal Trade Commission gives fibers generic names based on fiber chemistry. Manufacturers may also use trade names for the fibers they produce.

Fiber production
The process of producing a manufactured fiber is called spinning. Whether fibers are regenerated or synthetic, the spinning process is the same. The only significant differences occur in the production of the solution from which the fiber is made. Raw materials are made into a spinning solution (dope) by dissolving them in chemicals. I do not have the necessary knowledge of chemistry to understand the solution production process, and information about that process is not taught in my class, so I will speak of it no more. Fiber manufacture follows three steps:
1. Prepare a dope or melt
2. Extrude the dope or melt through a spinneret to form a fiber
3. Solidify the fiber by coagulation, evaporation, or cooling.

The spinneret is like a showerhead through which the dope is forced. The size and shape of the holes in the spinneret determine the size and shape of the fiber.

Manufactured fibers may be used in filament or staple form. Filament yarn is made by twisting filament fibers together. Filament tow is a rope of thousands of untwisted filament fibers. It is cut to make staple fibers. The fibers may be crimped.

There are three basic methods of fiber spinning:
Wet spinning: Raw material is dissolved by chemicals to produce a dope. The fiber is spun into a chemical bath where it solidifies. Wet spinning is the oldest and most complex method of fiber manufacture. The solvent and chemical bath are hazardous materials that must be recovered. Wet spinning can be used to produce acrylic, lyocell, rayon, and spandex. Wet spinning is rarely used.

Dry spinning: Resin solids are dissolved by chemicals to produce a dope. The fiber is spun into warm air where evaporation of the solvent causes the fiber to cool and solidify. The solvent must be recovered, but without the chemical bath there are fewer hazardous materials than in wet spinning. Dry spinning can be used to produce acetate, acrylic, modacrylic, and spandex.

Melt spinning: Resin solids are melted to produce a dope. The fiber is spun into air where it cools and solidifies. It is the cheapest method of fiber production, and there are no solvents to be recovered. It can be used to produce nylon, olefin, polyester, and saran. Regenerated fibers are not produced by melt spinning.

Fiber modifications
Every step of the fiber manufacture process can be precisely controlled to produce uniform fibers with specific characteristics.

Spinneret modifications: The size and shape of spinneret holes can be adjusted to produce fibers with specific dimensions. Hollow fibers may be created by adding gas forming compounds to the dope, by injecting air into the fiber as it forms, or by altering the shape of the spinneret hole. Hollow fibers are good insulators.

Molecular structure and crystallinity modifications: The molecular structure and the degree of crystallinity of a fiber contribute to its properties. These can be altered in the manufacture process by a controlled stretching of the fiber after it exits the spinneret or by selecting specific compounds used to produce the polymers. High tenacity fibers may be produced by stretching the fibers to line up the molecules and /or by chemical modification of the polymer to increase the degree of polymerization. I am not really sure what that all means. I never liked organic chemistry. The molecules are too big. I prefer physics where all the really exciting stuff happens in spaces smaller than an atomic nucleus.

Dope additives: Chemicals may be added to the dope to alter the fiber’s properties. Dyes may be added to color a fiber. Solution dyed fibers retain color better than fibers dyed after they are produced. Dye-accepting chemicals may be added to make a fiber more dyeable. Whiteners may be added to make fibers look whiter and resist yellowing. Delusterants may be added to reduce a fiber’s luster.

Modifications in fiber spinning: Crimp may be added to manufactured fibers by altering the way the fiber cools and solidifies. Filament fibers can be cut to create staple fibers.

Bicomponent fibers: Two polymers may be combined in a single fiber. Bilateral fibers are spun with two polymers side by side. Core-sheath fibers have one polymer encircled by another. The different polymers may react differently to heat and moisture, or each may have specific characteristics that are desired in the finished fiber.

Regenerated fibers
Regenerated fibers are produced from naturally occurring polymers that do not occur naturally as fibers. Cellulose and protein may be uses to produce regenerated fibers.

Rayon, lyocell, acetate, bamboo, and PLA are regenerated cellulosic fibers.

Azlon is the generic name for all regenerated protein fibers.

Rayon was the first manufactured fiber. The earliest form of rayon was invented in 1846, but it was highly explosive. Commercial production of viscose rayon began in the U.S. in 1911. Rayon is produced with the wet spinning method.

There are three types of rayon: Viscose rayon, cuprammonium (cupra), and high wet modulus (HWM) rayon. Viscose was the first type of rayon commercially produced, and HWM is the newest. Cupra is sold with the trade name Bemberg®. HWM is sold with the generic name polynosic and the trade name ModalTM.

Physical structure of rayon
Rayon can be either staple or filament. The fiber has lengthwise lines called striations. It has a serrated or indented circular cross section. This is caused by the fiber collapsing in on itself during coagulation from loss of the solvent. Cupra and HWM have a rounder cross section than viscose.

Properties of rayon
Aesthetics: Rayon can be produced to look like cotton, flax, wool, and silk.

Durability: Rayon is a low tenacity fiber that loses up to 50% of its strength when wet. HWM rayon is stronger than cupra, and cupra is stronger than viscose. Viscose has a breaking elongation of 8% to 14%. HWM rayon has a breaking elongation of 9% to 18%. Rayon may be permanently damaged by water.

Comfort: Rayon has a soft, smooth hand. It is highly absorbent, a good conductor of heat, and it does not build up a static charge.

Appearance retention: Rayon has low resiliency and dimensional stability. Viscose rayon may stretch or shrink. HWM rayon has better dimensional stability; it is less likely to stretch or shrink.

Care: Viscose rayon should be dry-cleaned. Cupra and HWM rayon may be machine washable; read the care label. Rayon is resistant to heat and may be ironed with high temperatures. Rayon may be damaged by silverfish and mildew, so it should be stored dry.

Environmental impact: Most rayon is produced from wood pulp. The fiber is biodegradable, but it cannot degrade if it is placed in a landfill. The wet spinning process uses large quantities of chemicals that may contribute to air and water pollution. Cupra is no longer produced in the U.S. because manufacturers were unable to comply with water and air quality requirements.


Lyocell was introduced in the early 1990s. It was originally sold as a type of rayon, but it differs from rayon enough that it now has a separate generic classification. Lyocell is sold with the trade name Tencel®

Physical structure of lyocell
Lyocell fibers can be staple or filament. The fibers have a smooth surface and round cross section.

Properties of lyocell
Aesthetics: The luster, drape, and texture of lyocell can be varied. Lyocell imitates the aesthetics of the natural cellulosic fibers, but it most closely resembles cotton. Lyocell fibers may pill.

Durability: Lyocell is the strongest regenerated cellulosic fiber. Its breaking tenacity is 4.8 to 5.0 g/d dry and 4.2 to 4.6 g/d wet. Lyocell has good abrasion resistance and poor elongation.

Comfort: Lyocell has a soft, smooth hand. It resembles cotton. It has excellent absorbency and poor thermal retention.

Appearance retention: Lyocell has moderate resiliency; it wrinkles, but not as badly as rayon. Lyocell has moderate dimensional stability. It may shrink, but not too badly.

Care: Lyocell may be machine washed on gentle cycle or dry cleaned. Read the care label. It may be ironed with high heat. It may be damaged by mildew and insects.

Environmental impact: Lyocell is produced with the wet spinning method, but the solvents are recycled so hazardous waste is not produced. The chemicals used to produce lyocell are less harmful than those used to produce rayon. Lyocell is biodegradable, but if it is placed in a landfill it will not degrade.

Acetate was introduced in the U.S. in 1924

Physical properties of acetate
Acetate fibers can be staple or filament. Acetate typically has a lobular cross-sectional shape and lengthwise striations, but the shape of the fiber can be altered in the spinning process. Acetate is thermoplastic; it melts in high heat. Acetate dissolves in acetone.

Properties of acetate
Aesthetics: The aesthetic properties of acetate are excellent. It has high luster, good drape, and smooth hand and texture. It is often used to make fabrics for which good appearance is more important that durability and ease of care.

Durability: Acetate is not a durable fiber. Its dry breaking tenacity is 1.2 to 1.4 g/d, and it is slightly weaker when wet. Acetate has low abrasion resistance and elongation. Acetate is resistant to mildew and moths.

Comfort: Acetate has a smooth, soft, but slightly clammy hand. It has moderate absorbency. It builds up a static charge. It is a moderate insulator.

Appearance retention: Acetate has poor appearance retention. It has poor resiliency and elastic recovery, and moderate dimensional stability. It may shrink. Acetate may experience fume fading – its color changes. This may be prevented with solution dyeing.

Care: Acetate should be dry-cleaned. It melts at high temperatures, so it may only be ironed on low heat.

Other regenerated fibers
Bamboo is a type of rayon that uses bamboo as the source of cellulose. It contains no bamboo fibers. In the past few years bamboo has been marketed as an environmentally friendly fabric, but the claims were unsubstantiated. The FTC has recently taken action against manufactures of bamboo rayon barring them from making deceptive claims about the fabric. The FTC does not recognize “bamboo” as a generic name for bamboo based rayon.

PLA (polylactic acid) is a regenerated cellulosic fiber made from cornstarch. The FTC approved it as a generic fiber in 2002. It is sold with the trade name Ingo®. We had some PLA in lab. It seems great. I would like to find some of it to play with.

SoySilk® is a type of azlon. It is made from a soy protein that is a waste product of the tofu manufacturing process. Yummy. It is a durable fiber with a soft hand, great drape, good colorfastness, excellent absorbency, good comfort, and good thermal retention. We had some SoySilk® in lab too. I liked it a lot. If it isn't too expensive I want to use it to make a shirt.

Silk Latte® is a type of azlon made from milk protein. It is similar to SoySilk® but slightly less durable.

Monday, March 1, 2010

Textiles review: natural protein fibers

This is part three of my textiles review, in which we go over the natural protein fibers.

Natural protein fibers come from animals. Wools are the hair and fur of animals, and silk is secreted by silkworms. The protein in wools is keratin, and the protein in silk is fibroin. While the word “wool” technically refers to any hair fiber from any animal, it is commonly understood to refer only to sheep hair. Specialty wools (fibers from other animals) are usually referred to by the animal’s name, and they cost more than sheep wool.

All natural protein fibers share certain properties because of their common chemical composition. These properties are:

Resiliency: Protein fibers are resilient. They resist wrinkling, and wrinkles may disappear between uses. Wool is more resilient than silk.

Hygroscopic: Protein fibers are highly absorbent. They shed water slowly, so they retain their insulation properties and remain dry to the touch while wet.

Weaker when wet: Protein fibers have lower tenacity when wet. Silk loses about 15% strength when wet, and wool loses about 40%.

Specific gravity: Protein fibers have a lower specific gravity than cellulosic fibers.

Harmed by alkalis, oxidizing agents, and dry heat: Detergents, bleaches, and sweat damage the fibers. Steam should be use when ironing. Most protein fiber garments require dry-cleaning.

Flame resistant: Protein fibers do not ignite easily and will self-extinguish. They emit a burnt-hair smell and leave behind a black, powdery ash.

This section is about sheep wool. Specialty wools will be covered later.
Wool is a staple fiber from sheep’s hair. Wool is produced primarily in Australia, New Zealand, China, and Eastern Europe. The U.S. produces less than 1% of the world’s wool.

Wool production
Sheep are sheared once per year, usually in the spring. A newly removed fleece (raw or grease wool) contains 30% to 70% by weight of impurities such as dirt, grease, and sweat. The fleece is cleaned to produce scoured wool. The fleece is graded to evaluate it for fineness and length, then sorted to separate the sections of different qualities. Wool fibers are laid parallel to one another and twisted together to make yarns. Felt is made by pressing wool fibers together without twisting them into yarns.

Physical structure of wool
Length: Long, fine wool fibers, with an average length of 2½ inches, are used for worsted yarns. Short, coarse fibers, with an average length of 1½ inches, are used for woolen yarns.

Longitudinal view: Wool is a naturally crimped fiber. The fiber twists and bends back and forth around its axis giving it spring like qualities. The crimp accounts for wool’s excellent resiliency, flexibility, elongation, and elastic recovery.

Cross-sectional view: Wool fibers have diameters ranging from 10 to 50 micrometers. The fibers are round. The cuticle, the outer layer of the fiber, contains a dense layer of scales. These scales make the fibers water repellent, and allow felting. The cortex is the main part of the fiber. The cells on either side of the cortex react differently to moisture and temperature, giving wool its crimp. The center of the wool fiber is the medulla, a microscopic honeycomb-like structure containing air spaces. These air spaces add to wool’s thermal retention. Most worsted fibers do not contain medullas.

Properties of wool:
Aesthetics: Wool varies in color from white to dark brown. It accepts and holds dyes well. Woolen wool has a matte appearance; worsted wool may be more lustrous. Texture and drape are determined by yarn and fabric structure and by finish.

Durability: Wool fabrics are durable. Wool has a low tenacity (1.5 g/d), but its excellent elongation and elastic recovery allow it to resist damage. Wool’s wet tenacity is 1.0 g/d.

Comfort: Wool is highly hygroscopic – it is highly absorbent and it releases moisture slowly. Wool absorbs small droplets of moisture such as sweat while repelling larger droplets such as rain. Wool is a poor conductor of heat which makes it an excellent insulator. Wool continues to provide insulation while wet. Wool may induce an allergic reaction in some people.

Appearance retention: Wool is a highly resilient and elastic fiber. It resists wrinkling, and recovers its shape. If properly cared for wool has good dimensional stability, but if improperly washed it will shrink, felt, and tear. Wool should be dry-cleaned. Wool does not soil or stain readily, and with proper cleaning techniques stains can be removed.

Care: I can’t say this enough: WOOL IS DRY-CLEAN ONLY! Wool is damaged by alkalis (most detergents) and chlorine bleach. Moths eat wool; store your wool carefully. Wool is slow to ignite and it self-extinguishes, but there is still no good reason for you to set your wool clothes on fire.

Specialty wools

Mohair comes from the Angora goat. It is a smooth, silky, fine fiber without crimp. Most fibers do not have a medulla. Mohair is highly resilient.

Cashmere is from the Cashmere goat. The fibers have very fine scales and no medullas. It is used to make fabrics with a warm, soft, buttery hand, lustrous appearance, and excellent draping characteristics. It is expensive.

Llama and Alpaca wools come from South American cousins of the camel. Alpaca fiber’s soft hand, good luster, and excellent draping characteristics make it good for apparel. Llama fiber is coarser than alpaca fiber. It is often used for coats and suitings.

Camel’s hair is from the two-humped beasties (Bactrian camels). The hair is shed naturally; camels do not need to be shorn. The fiber provides great insulation without weight. It is usually used in coats, scarves, and suits. It is a tan fiber that is usually used undyed.

Angora is from the Angora rabbit. It is a long, fine, fluffy, soft, and slippery fiber. The fiber does not dye well. It is difficult to spin into yarns because it is so sleek, so it is often blended with other wools. Lambs are cute, but the Angora rabbit is the most adorable wool critter.

Silk is the only natural filament fiber. Silk was first used as a fiber in Chine more than 4,000 years ago. It is excreted by the silkworm to spin its cocoon in an attempt to metamorphose into a moth.

Silk production
Sericulture is the production of cultivated silk. Silk moths lay eggs on specially prepared paper. After the larvae hatch they are fed mulberry leaves. After roughly five weeks the caterpillars begin to spin their cocoons. Cocoons are made from a single strand of silk, approximately one mile long. The strands of silk are coated with a gum, called sericin. After the cocoon is finished, the pupa is killed with heat. The cocoons are unwound to produce fibers, the sericin is removed, and the fibers are wound together to produce yarn.

Wild silk is produced by collecting empty chrysalises from wild silkworms. The adult moth tears through the fiber as it exits the cocoon, so wild silk is a staple fiber. The sericin is not removed from wild silks.

Physical structure of silk
Silk is a smooth, thin fiber. The diameter of silk fiber is approximately 11 micrometers. It is a solid fiber with a triangular cross shape. Slight striations may be present along the length of the fiber. Wild silk tends to be coarser than cultivated silk.

Properties of silk
Aesthetics: Silk is a luxury fiber. It has a soft luster with an occasional sparkle. It wrinkles more easily than wool, but it is more resilient than cotton. Its color, hand, and drape vary. Wild silks have duller luster and more texture than cultivated silks.

Durability: Silk is one of the strongest natural fibers with a dry tenacity of 4.5 g/d. It loses up to 20% strength when wet. Silk has medium elasticity; at 2% elongation it returns to only 90% of its original length. Silk is damaged by sweat, body oils, chlorine bleach, sunlight, mineral acids, metallic salts (deodorants), and carpet beetles. It is resistant to hydrogen peroxide.

Comfort: Silk is a poor conductor of heat, so it can provide insulation. Light weight silk fabrics are comfortable in warm weather. It has good absorbency, and it is hygroscopic. Silk may develop a static charge. Silk has a soft, smooth, silky hand.

Appearance retention: Silk has moderate resistance to wrinkling. With its low elasticity, if it gets stretched it will stay stretched. Silk has moderate abrasion resistance, but with its typical uses it is rarely subjected to harsh abrasions. Staple silk may pill.

Care: Silk should by dry-cleaned. Silk may be pressed at moderate heat (300oF) with a damp press cloth. Silk is flame retardant and self extinguishing, but you should still keep it away from open flames.

Types of silk
Tussah is the most common type of wild silk

Noil silk (waste silk) is a staple fiber made from the broken pieces and cocoon remnants of cultivated silk.

Duppioni silk is made if two silkworms spin their cocoons together. It is not possible to fully separate the fibers. The yarns have a thick-and-thin appearance. It is used to make shantung.

Spider silk is not currently commercially produced, but several researchers are attempting to develop cost effective ways to produce it. The protein in spider silk is spidroin. Spider silk has excellent tenacity and elasticity. Efforts have been made to collect the silk directly from spiders and to genetically enhance silkworms and goats to produce it. A piece of spider silk fabric is currently on display at the American Museum of Natural History in New York.