Section+1.1B

=Flax (Linen) = Home, @Section 1.1, Section 1.1A, Section 1.1B, Section 1.1C, Section 1.2, Section 1.3

Flax fibers are used to produce linen yarns and fabrics. The widespread use of linen for many purposes is reflected in terminology that is still used, such as bed linens or table linens. However, these days, bed linens and table linens are usually made from fibers other than flax.

The interest in linen saw a big growth in the early 1990s by environmentally minded consumers because flax is grown almost completely free of herbicides and pesticides. The United States imports linen fibers, yarns, fabrics, and completed garments, although flax for fibers is not commercially cultivated here. Although it is being grown experimentally here, and new processing methods are being investigated. Countries that produce large quantities of flax fiber are Poland, Belgium, France, the Netherlands, and the Czech Republic.

The botanical name of the flax plant is Linum usitatissimum; usitatissimum is Latin for "most useful." Before cotton was available in Western Europe, linen was used extensively in household textiles, for practical and washable garments, and for tents and sails for boats. Its many uses are clearly reflected in the Latin name given to the plant. Some varieties of the plant are grown for fiber, whereas others are grown for seeds. The plant grows to a height of 2 to 4 feet and produces flowers with blue or white petals. The fibers grow in bundles in the bast layer of the stem, just underneath the bark.
 * The Flax Plant**

Different varieties of flax are grown for seed and fiber. Plants for fibers are taller with fewer branches. The plant thrives best in average climates with adequate rainfall, with cultivation throughout Europe and in Russia. Limited quantities are grown in the United States, primarily as an experimental crop.
 * Cultivation**

Harvesting is done about 80 to 100 days after sowing when about one-half of the seeds are ripe and leaves have fallen from the lower two-thirds of the stem. In those countries where inexpensive labor is readily available, flax is still harvested by hand, but in developed countries, much of the labor of flax pulling is now done by machine. Whether done by hand or machine, the flax plant is pulled completely from the ground. Removing plants from the ground retains as long a stem as possible and prevents discoloration of fibers through wicking.

Stalks are dried well so they can be threshed, combed, or beaten to remove the flax seeds, which are used for planting future crops or for making linseed oil or livestock feed.

Bast fibers require extensive processing to remove the fibers from the woody stem in which they are held, a factor that increases the cost a great deal. The procedure is similar for all bast fibers. The deseeded flax straw has to be partially rotted to dissolve the substances that hold the fiber in the stem. This first step in preparing the fiber is called //retting//.
 * Preparation of the Fiber**

Retting is accomplished through the breakdown of the materials that bind the fibers into the plant stems. Highly specific enzymes that attack only the binding materials and not the fibers are secreted by fungi and bacteria. Retting processes are of three types:
 * 1) //Dew (or ground) retting// is the most common method today. The flax is laid out in swaths in a field where the action of rain and dew together with soil-borne fungi and bacteria cause the bark of the stems to loosen. This may take from 3 to 6 weeks, depending on weather conditions. After retting, the bark is removed, and retted straw bundles are set up in the fields to dry. Disadvantages of of dew retting that affect fiber quality are variable weather and lack of control because the process is dependent on naturally occurring microorganisms. On the other hand, it is environmentally benign and can be easily mechanized.
 * 2) //Water retting// takes place when flax is submerged in water for 6 to 20 days, with warmer water temperatures decreasing the time required. Water retting may be done in ponds, in vats, or in sluggish streams. As in dew retting, the bacterial action causes the bark to loosen. Water retting yields finer fibers but is more costly and produces odors and pollutants in the retting water; therefore, the less expensive and more easily mechanized dew retting process is generally preferred.
 * 3) Chemical retting processes using sodium hydroxide or oxalic acid have been developed but currently are rarely used.
 * 4) Enzyme retting, a recent development, exposes the flax stems under controlled conditions to enzymes that act specifically on the material holding the fibers to the bark. While not commercially implemented, enzyme retting is a promising process because it yields a high-quality fiber without the disadvantages of water retting.

Retting only loosens the bark from the stem. After retting, //breaking// and //scutching// finish the job of separating the fiber from the stem. In breaking, the flax straw is passed over fluted rollers or crushed between slatted frames. This breaks up the brittle, woody parts of the stem, called //shive//, but does not harm the fiber. In scutching, the broken straw is passed through beaters that knock off the broken pieces of stem. The fibers are baled and shipped to spinning mills.

At the mill, fibers go through yet another process before they are ready for spinning. The fibers are //hackled//, or combed, to separate shorter fibers from longer fibers and to align fibers parallel to prepare them for spinning. Even with all this processing, individual fibers do not separate out, and bundles of fibers continue to cling together. Flax fibers are long; therefore, they must be processed on specialized machinery.

Physical Properties (Image taken from http://www.swicofil.com/products/003flax.html) Mechanical Properties Chemical Properties Environmental Properties Other Properties
 * Properties of Flax**
 * Color. Unbleached flax varies in color from a light cream to a dark tan. The different retting methods produce differences in fiber color. Dew retted fibers are grayer and darker. Water and enzyme retting produce whiter fibers.
 * Shape. Fiber bundle length may be anywhere from 5 to 30 inches, but most line (longer) fiber averages from 20 to 30 inches, whereas tow (shorter fiber) is less than 15 inches. Recent interest in cotton/linen blended fabrics has led to cutting of flax fibers to shorter lengths, a process step referred to as "cottonizing." Single fiber diameter averages 15 to 18 microns. In microscopic cross section, flax has a somewhat irregular, many-sided shape. Like cotton, it has a central canal, but its lumen is smaller and less distinguishable than that of cotton. Looking at the lengthwise direction of fiber under the microscope is rather like looking at a stalk of bamboo. Flax has crosswise markings spaced along its length that are called //nodes// or //joints// (see image below).
 * Luster. Because it is a straight, smooth fiber, flax is more lustrous than cotton, but it does not have the smooth surface that most manufactured fibers display. A special finishing technique called //beetling// can be used to increase the luster of linen fabrics.
 * Specific Gravity. The specific gravity of flax is the same as that of cotton (1.54). Linen fabrics are, therefore, comparable in weight to cotton fabrics but are heavier than silk, polyester, or nylon, even in cloth of similar weave.
 * Strength. Flax is stronger than cotton, being one of the strongest of the natural fibers. It is more crystalline and more oriented than cotton. It is as much as 20 percent stronger wet than dry.
 * Modulus. Flax fibers have a high modulus. In former days sails were made of linen because it resisted the wind forces without deforming greatly.
 * Elasticity and Resilience. The elongation, elasticity, and resilience of flax are lower than those of cotton because linen lacks the fibril structure that gives some resilience to cotton. Linens crease and wrinkle badly unless given special finishes.
 * Flexibility. Just as flax fibers resemble bamboo stalks, they also display the brittleness one associates with bamboo. Although fairly soft fabrics can be made from very fine yarns, generally linen fabrics feel stiff because the fibers have high resistance to bending.
 * Absorbency and Moisture Regain. Moisture regain of linens is higher than that of cotton (11 to 12 percent). Unlike cotton, linen has very good wicking ability; that is, moisture travels readily along the fiber as well as being absorbed into the fiber. Both absorbency and good wicking ability make linen useful for towels and for warm-weather garments.
 * Heat and Electrical Conductivity. Linen conducts heat more readily than does cotton and is even more comfortable for summer wear. Conductivity of electricity prevents static electricity buildup.
 * Effect of Heat; Combustibility. Linen is slightly more resistant to damage from heat than is cotton, and higher temperatures are required to scorch linen fabric. The burning characteristics of linen are similar to those of cotton; it is combustible, continues to burn when the flame is removed, and burns with an odor like that of burning paper.
 * Chemical Reactivity. The chemical reactions of linen closely parallel those of cotton because both are composed of cellulose (plant fibers). Like cotton, linen is destroyed by concentrated mineral acids, not harmed by bases or decomposed by oxidizing agents, and not harmed by organic solvents used in dry cleaning.
 * Resistance to Microorganisms and Insects. If linen is stored damp and in a warm place, mildew will attack and harm the fabric. Dry linen is not susceptible to attack. It generally resists rot and bacterial deterioration unless it is stored in wet, dirty areas. Moths, carpet beetles, and silverfish do not usually harm unstarched linen fabrics.
 * Resistance to Environmental Conditions. Linen has better resistance to sunlight than cotton does. There is a loss of strength over a period of time, but it is gradual and not severe. Linen drapery and curtain fabrics are quite serviceable. The resistance of linen to deterioration from age is good, especially if fabrics are stored properly. Linen, however, has poor flex abrasion resistance. To avoid abrasion and cracking at folded edges, a linen fabric should not be repeatedly folded at the same place.
 * Dimensional Stability. Like cotton, linen has poor dimensional stability because the fibers swell when exposed to water. Tension from manufacturing, therefore, results in often considerable relaxation shrinkage of fabrics. Preshrinkage treatments can be applied to linen fabrics to prevent relaxation and shrinkage.
 * Abrasion Resistance. Linen fabrics have fairly low abrasion resistance. Because of their high bending stiffness, their flex abrasion is also low.

Linen fabrics, traditionally found most often in household textiles, saw expanded markets in apparel in the 1980s and 1990s as a result of new developments in processing equipment and a renewed interest in natural fibers. Yarns spun from flax range form extremely fine for weaving into sheer, soft "handkerchief" linens to coarse, large-diameter yarns for suiting fabrics, enabling a wide range of choices for apparel. The European Linen and Hemp Confederation developed a promotional program for both apparel and home furnishings linen textiles using the //Masters of Linen// logo (see image below). (Image taken from http://www.alexandre-turpault.co.uk/pages/Partners-websites)
 * Uses**

Because of their high moisture and wicking ability, linen fabrics are popular for summer clothing. The major disadvantage of linen clothing, its wrinkling, may be somewhat overcome by giving fabrics the special wrinkle-resistant finishes and is less of a problem in knits. Blending of fabrics with synthetics can also improve wrinkle recovery. Many casual linen garments today are prewashed for a soft, slightly wrinkled look. A softer look can also be achieved by blending short staple cottonized flax with other fibers.

The launderability of linen combined with its good luster and attractive appearance make it popular for use in tablecloths, napkins, and place mats. Linen is a favorite for tea towels; because flax fibers are longer, linen produces less lint (small bits of fiber that break off from the yarn) than does cotton and is, therefore, preferred for drying glassware. Linen is used alone or in blends for household products such as curtains and in slipcover and upholstery fabric. Heavy yarns can provide interesting textures for these fabrics, but poor abrasion resistance is a disadvantage.

Linen can be dry-cleaned or laundered at home. Being stronger wet than dry, the fabric requires no special handling during laundering. Excessive chlorine bleaching damages linen, but linen fabrics can be whitened by the periodic, controlled use of chlorine or other bleaches. Even though linen can be laundered, many care labels on linen textiles carry the instructions "Dry Clean Only." This is because the fabrics are likely to exhibit considerable shrinkage and to wrinkle badly. Fabrics do not wrinkle or suffer as much color loss after dry cleaning as they do after laundering. Ironing temperatures for linen are at the highest end of the dial on electric irons. Linen fabrics can be ironed safely at a temperature of 450 degrees Fahrenheit and usually require steam to remove the wrinkles. Dryer drying at the highest setting is satisfactory.
 * Care Procedures**

Footnote: information quoted and paraphrased from (Bide, Collier & Tortora, pp. 73-80).