Lyocell - One fiber, Many Faces

HYG-5572-99

Joyce Ann Smith, Ph.D.
Extension Specialist, Clothing

Whether the need is denim for casual looks or sueded silk- like ensembles for evening wear, lyocell can create the right look and the right fabric. In 1996, lyocell became the first new generic fiber group in 30 years to be approved by the Federal Trade Commission. Since then, lyocell has realized increasing visibility and acceptance in the apparel market, especially in designer and better priced garments. Its versatility and desirable properties provide many advantages, both functional and aesthetic.

Background

Lyocell was developed by Courtaulds fibers (now Acordis Cellulosic fibers), an international supplier of rayon. It entered the consumer market in 1991. The properties and production processes were unique enough for the Federal Trade Commission to designate it as a separate fiber group. The trade name for lyocell produced by Acordis is Tencel. Lenzing fibers, another major manufacturer of rayon, has also entered the lyocell market. This product is marketed as Lenzing lyocell. An improved fiber, in terms of performance and properties, lyocell is also friendly to the environment. Virtually all of the chemicals used in the production process are reclaimed. The resulting fiber, lyocell, is both biodegradable and recyclable.

Properties and Characteristics

Lyocell is a manufactured fiber, but it is not synthetic. It is made from wood pulp harvested from tree farms for this purpose. Because it is made from a plant material, it is cellulosic and possesses many properties of other cellulose fibers, such as cotton, linen, ramie, and rayon - another manufactured but non-synthetic fiber.

In many ways, lyocell is more similar to cotton than it is to rayon. Like other cellulosic fibers, it is breathable, absorbent, and generally comfortable to wear. In fact, lyocell is more absorbent than cotton and silk, but less so than wool, linen, and rayon. It can take high ironing temperatures, but like other cellulosics will scorch, not melt, if burned, and is susceptible to mildew and damage by silverfish. Cellulosic fibers are not resilient, which means they wrinkle. Lyocell has moderate resiliency. It does not wrinkle as badly as rayon, cotton, or linen, and some wrinkles will fall out if the garment is hung in a warm moist area, such as a bathroom after a hot shower. A light pressing will renew the appearance, if needed. Also, slight shrinkage is typical in lyocell garments. Stability, overall, is similar to that of silk and better than cotton or linen.

Lyocell has strength and durability. It is the strongest cellulosic fiber when dry, even stronger than cotton or linen and is stronger than cotton when wet. Lyocell is much stronger than rayon when wet. This property of high wet strength usually determines the extent to which fabrics can be machine washed successfully (see Care below).

Other desirable properties of lyocell are its luster and soft drape which makes it an aesthetically pleasing fiber. Since it is a manufactured fiber, the diameter and length of fibers can be varied. Lyocell can be made into microfibers (very fine fibers), offering depth and body to fabrics combined with luxurious drape. Short staple length fibers give a cotton-like look to fabrics. Long filament fibers are successful in silk-like end uses. Lyocell blends well with other fibers including wool, silk, rayon, cotton, linen, nylon, and polyester. It successfully takes many finishes, both functional and those designed to achieve different surface effects, and dyes easily. Overall, lyocell is a versatile fiber with many desirable properties.

Uses

Lyocell was initially marketed as and can generally be found in high end and designer apparel. Production costs are greater than for cotton, making lyocell more expensive in finished garments. However, as production increases and costs decrease, expect to see more lyocell in moderately priced apparel. Lyocells soft drape and luxurious hand make it very desirable in womens fashion garments as well as mens shirts, particularly apparel traditionally made from silk. Other lyocell end uses include denim, chino, and chambray casual wear. Look for these fabrics in 100% lyocell as well as in blends with cotton, rayon, or polyester.

Tencel lyocell gabardines take water resistant finishes for coatings. Other fabrics successfully made from lyocell include jersey-knits, which exhibit a soft hand and luster. As lyocell becomes more available and manufacturers gain experience handling it, look for more varieties of fabrics including knits of all types, leotards and hosiery, velvets, velours, and corduroys.

Look for Tencel lyocell blended with Tactel nylon in which the Tactel is on the surface for durability and wind and water resistance, while the Tencel
has greater exposure on the backing surface for warmth, absorbency, and comfort. Blends with wool and wool with Lycra spandex and Tencel have been successful. Blends of lyocell with cotton, linen, and rayon, will continue to be available, especially for spring, summer, and fall fashions. In addition, blends with silk and rayon are common, especially in lightweight silky fabrics including those with sueded surfaces.

To some extent, lyocell is available in home products including bath towels, sheets, pillowcases, and window treatments. Industrial uses for lyocell include conveyor belts (because of the fiber's strength), ultra-low tar cigarette filters, printers blankets, abrasive backings, carbon shields, specialty papers, and medical dressings.

Care

Because of its high wet strength and cellulosic or plant base, lyocell can generally be either hand washed or machine washed and tumbled dried successfully; however, some lyocell fabrics perform best when dry cleaned. Reading care labels and following recommendations is especially important, since the type of processing used in the manufacture of lyocell will determine whether dry cleaning, hand washing or machine washing is recommended. (See "More Than You Might Like To Know" below.)

Lyocell fabrics that require dry cleaning may have either a smooth or sanded surface. If machine washed or hand washed, they could develop a "hairy" surface. In addition, water spotting may be noticeable in some fabrics that are "spot" cleaned to remove stains. Wrinkling may occur after wetting the fabric.

Hand washable/line dry lyocell fabrics are frequently knits (often blended with rayon or cotton) or wovens, such as chambray or sandwashed "silk-like" fabrics. When wet, fabrics made from lyocell become stiff and almost boardy. Although this improves as drying occurs, undesirable stiffness may be removed by tossing the garment into the dryer with a towel on low temperature to enhance the fabric's softness and drape.

Machine wash and tumble dry lyocell fabrics are either treated with a special finish or modified as they are manufactured. Look for woven and knitted fabrics, such as jersey, sweaters and hosiery, sueded surface fabrics, denim, chino cloth for men's and women's wear, and in household textiles including sheets and towels. These fabrics can be machine washed and tumble dried much like cotton or cotton/polyester blends are handled in the home laundry. Medium temperature settings for water and drying are recommended as well as permanent press settings. If line dried, be sure to toss in the dryer with a damp towel to soften the fabric after it is dry or nearly dry.

Remember, lyocell is a cellulosic fiber and, as a result, will wrinkle. It may need a slight touch up with a warm iron. Because lyocell is similar to cotton, it can take medium to high temperature settings. The exception is fabric made from fine yarns or microfibers. Heat will penetrate these fabrics more quickly with the potential for scorching. In many instances, however, wrinkles are likely to hang out overnight, particularly in a warm, moist environment.

Generally, use of oxygen or chlorine bleaches should not damage the lyocell fiber itself, but may affect either dyes or resin finishes applied to the fabrics. Check care instructions before treating with bleach. Also, because the surface of some fabrics can be damaged when wet if subjected to abrasion, avoid excessive rubbing during stain removal.

Overall, read and follow care label instructions. The different processing treatments for lyocell determine the recommended care. As a consumer, you are not likely to know the exact type of lyocell you have. Also, occasionally, the lining, trim, or other construction materials may dictate a particular care method, regardless of the fiber content and properties.

More Than You Might Like To Know

A better understanding of the lyocell fiber may help explain the variation in care methods. A unique property of lyocell is that the fibers "fibrillate" when wet and are mechanically agitated, like you would get in a washing machine. When the fibers get wet, they swell and become almost "boardy." Fibrillation is the peeling back or splintering of the fiber ends to form tiny "hairs" on the surface. Think of each fiber as a banana. Small fibrils or sections of the fiber splinter and pull away like a banana peel. These surface fibers mat together and detract from the appearance of the finished fabric. Fibrillation can be handled by preventing it from happening or by using it to advantage.

fabrics made from lyocell that is not specially treated to prevent fibrillation are usually labeled as "dry clean only." Reduced moisture and agitation during dry-cleaning prevent fibrillation. Garments made this way should perform satisfactorily if care recommendations are followed.

Another way to control fibrillation is in the manufacturing process. fabric is washed, then treated with an enzyme that attacks cellulose fibers. (Note: Many home laundry detergents contain a similar enzyme designed to keep cotton looking newer longer and colors brighter; the cotton symbol is used on these detergent boxes.) This "cotton-eating" enzyme "eats" the hairs from the fiber surface. The fiber is then washed and agitated again. Some secondary fibrillation occurs which produces sueded or sandwashed surfaces. The resulting fabric is similar in texture and drape to sueded silk or sueded rayon found in fashion apparel. fabrics processed this way can usually be machine washed and line dried successfully. Tossing these fabrics in the dryer with a damp towel for a few minutes when dry or almost dry will restore the softness and drape. This approach to processing uses the tendency to fibrillate to advantage to create a sandwashed textured fabric.

The third alternative to preventing fibrillation is chemical treatments in the last step of fiber and fabric processing. fabrics processed this way can successfully be machine washed and tumble dried. These fabrics will generally have a smooth surface, such as chino for slacks and jackets, as well as knits for both hosiery and sweaters. Acordis Cellulosic fibers, which produces Tencel
lyocell, markets this fiber as Tencel
A-100 non-fibrillating fiber.

In order to maintain standards and performance of fabrics made from Tencel
lyocell fibers, Acordis conducts a registration program. To display the registration mark, which is in the form of a triple "X," fabrics must be at least 40% Tencel
lyocell, meet performance standards established by Acordis, and be tested for care instructions stated on the care label.

Although initially and primarily used in high end fashion apparel, also look for lyocell in more moderately priced lines as well as household linens. The fiber offers many desirable properties of natural fibers, both functional and aesthetic, with the uniformity of a manufactured fiber combined with environmentally friendly production methods.

References

Fiber of the future. Tencel

Finlen, M. (1998) (Acordis Cellulosic fibers). Recent developments in Tencel
lyocell and rayon. Presentation at American Association of Family and Consumer Sciences Annual Meeting, Atlanta, GA; June 29.

Horrocks, D. (1993) (Courtaulds fibers). Rayon--What's happening now? Presentation at Textile Update Inservice, Ohio State University Extension, Columbus, OH; October 26.

Kadolph, S. J. and Langford, A. L. (1998). Textiles (8th ed.). Upper Saddle River, NJ: Prentice-Hall.

Lyocell by Lenzing. www.Austria.eu.net/lyocell/

Manufacture of lyocell fibre. www.texguide.com/news_group/lyocell.html

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