Synthetic vs. natural dyes … Colorfastness … Vat dyes … Fiber or stock dyeing, piece dyeing, garment dyeing … Crocking and frosting … Pigments and prints … Finishing treatments for absorbency, antisepsis, antistatic, antiwrinkling … Beetling, bleaching, calendering, and crêpeing and similar procedures … Flame resistance … Glazing, mercerizing, mothproofing, nanotechnologies, napping and sueding, preshrinking, resin treatments, soil resistance, ultraviolet protection, stiffening treatments, and water resistance
What happens to cloth after it is woven may substantially transform its look and behavior and, more often than not, is what matters most to us when we go looking for clothes or furnishings. We tend to take the structure and fiber quality of the cloth for granted. What we want to know is what color it is and whether we have to iron it or wash it separately. The answers often depend on what dyes and finishes have been used.
Inferior dyeing can wreck the appearance of the finest cloth and greatly reduce its usable life, or cause expense in dry cleaning or the inconvenience of separate or hand-washing. Modern finishing treatments, from resins that prevent wrinkling to napping that creates a warm, fuzzy surface, significantly affect how you care for the cloth, what you can use it for, and how it looks.
Dyes
Almost all dyes used on textiles today are synthetics, derived from coal-tar distillates or petrochemicals rather than from plants, minerals, or animals. Functionally, synthetic dyes are available that are considered superior in almost every respect to natural ones. Environmental and health issues have occasionally been raised concerning synthetic dyes, however, and some synthetic dyes have been found to be potentially carcinogenic and banned from use. Natural dyes, on the other hand, are hard to find and expensive, and they may present environmental problems of their own as a result of the use of toxic metals, such as chrome, copper, tin, and zinc, to improve colorfastness and light resistance. Aluminum and iron may be relied upon as substitutes for these metals, but they are less effective. The production of natural dyes also requires the use of much agricultural land.
Colorfastness, the resistance of color to removal or extraction, is a complex set of behaviors. Fastness may be tested against different substances used in laundering, such as soap or detergent, bleach, and water (cool, warm, and hot), or in dry cleaning (a variety of solvents); light; acidic and alkaline solutions; heat; and perspiration. Some colors withstand laundering of any sort but fade in the light; these, obviously, should not be used for drapery or upholstery. Some fade or bleed in laundering but not in dry cleaning. Vat dyes, so called because the first of them, indigo, was steeped in a vat, are widely used on cellulosic fibers such as cotton, linen, or viscose rayon. They result in color with excellent fastness to washing—even with the strong bleaches used by professional laundries—and to light. (Among dyes commonly in use today, indigo, used for blue jeans and other blue denim cloth, inevitably fades, and is valued for this property. I know of someone who refused to wear a pair of inexpensive blue jeans that had a herculean resistance to fading: they looked like new even after half a dozen launderings with chlorine bleach.)
A dye’s performance is determined not only by the type of dye but also by what fabric and fiber it is used on and the method used to apply it. Dye (or pigment) can be applied at almost any point in the manufacturing process. It may be added to the solution out of which man-made fibers are produced (referred to as “solution dyed” or “producer dyed”) or to the fibers out of which yarn will be spun (“fiber dyed,” “stock dyed,” or “top dyed,” tops being the long fibers out of which wool worsted is spun). Or it may be applied to the yarn out of which fabric is woven (“yarn dyed”); or the woven fabric may be dyed in the piece or after the garment is made (“piece dyed” and “garment dyed”). Tweeds are stock dyed; the fibers are dyed before they are woven into yarn. Gingham, chambray, and denim are yarn dyed, as are most fabrics containing two or more colors of yarn, such as plaids or checks. The dyeing of already made-up articles is fraught with dangers. Poor penetration by the dye at seams, discoloration of trim, uneven color, and similar problems all become more likely. As a rule of thumb, the earlier in the production process the color is added, the more likely the product is to have uniform coloring, good penetration, and good colorfastness, but these are likelihoods, not guarantees.
Colorfastness and uniform color are not the only important characteristics of a good dye or dyeing process. Good dyes will not readily yellow or otherwise discolor. Good color will neither crock (transfer color to other surfaces when rubbed against them) nor frost (show areas where color has been rubbed off by abrasion). When jeans are stonewashed, they are subjected to abrasion to create frosting intentionally, but ordinarily this effect is unwelcome. Frosting can result unintentionally when the dye has not penetrated the fabric thoroughly. As the outside of the fabric wears off from abrasion, so does the dye, and light areas begin to show. Bleeding of dyes is also a headache for home launderers. Manufacturers are required to warn you on care labels to wash items likely to bleed separately from others, which might otherwise pick up the color left in the wash water by the bleeding articles. But this can be exceedingly inconvenient. (Remember that towels sometimes bear no care labels. If they have bright or deep colors, wash them separately a few times, after which, if they are the product of a good manufacturer, they will cease giving up color.)
Pigments—which do not actually unite with the fibers as dyes do, but are attached to their surface by means of resins—can be used on any type of fiber. They tend to be fast to light and bleach. When deep colors are achieved with pigments, however, the colors sometimes have a tendency to crock. Pigments have fair fastness to washing. Pigments are also used in a dyeing process for manufactured fibers called “mass pigmentation,” in which the pigment is added to the spinning solution. This is as yet not a versatile method, and certain technical problems stand in the way of its widespread use. However, it is desirable for dyeing polypropylene satisfactorily. It provides lightfastness not available by other means in nylon and polyester.
Prints are fabrics with colored designs (usually created with pigments) that are applied to their surfaces. The design can be screened, heat-transferred, rolled, or stamped onto the cloth or applied to it in still other ways. In poor-quality prints, you may see bits of pattern askew or off their proper place, areas that have not received color, a lack of fine detail, fuzzy edges, and similar imperfections.
As the case of the unfading blue jeans illustrates, we should not assume that fading of fabrics after a few launderings is natural and unavoidable. Care and skill in the use of dyes can produce products that resist fading, bleeding, crocking, frosting, and discoloration. Unfortunately, once the ordinary buyer has examined a fabric for good appearance, he or she has no way of judging further how the dyeing will perform with use and with laundering or dry cleaning. Catalogues sometimes announce that a garment is yarn dyed; or occasionally a tag boasts of “only pure natural dyes”—a probable contradiction in terms, according to one expert in textile dyes. But aside from what you can learn by performing some simple home tests for colorfastness (see chapter 1, “Gathering, Storing, and Sorting Laundry,” pages 21-22), you are usually forced to glean bits of information from the fabric’s appearance and care label. It is truly a case of caveat emptor, for not even the principle that you get what you pay for holds at the retail level; many expensive items fade. Your best bet, which is by no means infallible, is to get what information you can from your retailer and to buy from reputable manufacturers and those whose products have proved colorfast in your home laundry. (In a store recently I saw a stack of knit tops displayed with the sign “Garment dyed!” As garment dyeing is typically a sign of lower rather than higher dyeing quality, the management of this store either labored in ignorance of its stock-in-trade or believed that its customers did.)
Finishing Treatments
When you purchase nonwrinkling shirts or blouses, mercerized thread for your sewing box, flame-resistant potholders, jeans with a suedelike hand, chintz upholstery fabric, or soil-resistant tablecloths, you bring home fabric that has been subjected to a certain finishing treatment through chemical or mechanical means. These and other finishing treatments can profoundly affect how well the fabric will function, how durably it will do so, and how you will have to care for it during its useful lifetime. Thus when you understand finishing treatments you can choose fabrics more wisely and take better care of them. Immediately below, descriptions are set forth of finishing treatments commonly applied to fabrics used in clothing and furnishings in the home. Chapters 21 and 22 take up in detail proper care for fabrics subjected to wrinkle-resistance and other resin finishes.
Finishing Treatments Commonly Applied to Fabrics
Absorbent Finishes. The natural absorbency of cotton, rayon, and linen may be increased by the use of absorbency treatments. Underwear and towels are sometimes treated for absorbency. Some treatments, applied to sanitary napkins, tampons, towels, and other materials used for drying and absorbing moisture, may increase absorbency dramatically. A variety of chemicals and resins are employed, depending on the fiber being treated and the use intended. Nylon and polyester may also be subjected to treatments to increase their absorbency. Sometimes they may be specially manufactured to increase their wicking capacity. Synthetics so treated are said to feel more comfortable against the skin, especially in warm and humid weather. But such claims are regarded skeptically by some, and I have been told that they have not stood up to double-blind trials. Mercerization (see “Mercerizing” on page 319) increases the absorbency of cotton (although that is not its purpose). The absorbency of natural fibers is decreased by resin treatments, fabric softener, and constructions using extremely tightly twisted yarns or weaves.
Antiseptics; Mildew Control. Antiseptic finishes may be used to help prevent athlete’s foot or to control odors in shoe linings, bedclothes, diapers, underwear, and socks. There are also finishes that can help prevent mildew damage to fabric and rotting on shower curtains, carpets and rugs, and elsewhere. The presence of various antimicrobial substances is indicated by the use of words such as these in labels: “antiseptic,” “bacteriostatic,” “antibacterial,” or “mildew-resistant.” (Linen, cotton, and rayon are particularly susceptible to mildew. Silk and wool will also mildew, although somewhat less readily. Most synthetics will not mildew, but some tend to retain body odors, and for this reason receive antiseptic finishes.)
Antistatic Treatments. Many synthetic fibers, especially polyester and nylon and their blends, are prone to building up static electricity when subjected to friction. (Olefin—polypropylene—an exception, tends to be low-static.) Garments made of these fibers gather static electricity when you wear them or tumble them in the dryer; carpets become charged when you walk over them. Among the natural fibers, wool and silk may develop static cling, too, particularly when the humidity is low, but not to the extent that synthetics do. Clinging, climbing, and minor electrical shocks and sparks that may be painful or even dangerous (for instance, in the presence of flammable gases) or destructive (to delicate electronic equipment) are some potential consequences of static electricity in clothing and furnishings. Static may also cause fabric to attract dirt. To prevent static buildup, manufacturers sometimes use antistatic finishes, but these are not durable. New forms of certain synthetic fibers have been developed with built-in resistance to static. If you are buying nylon carpeting, this is a feature to insist on.
At home one can use antistatic sprays or fabric softeners to reduce static effectively. Or one can choose naturally low-static or nonstatic fibers. Humidity reduces the amount of static electricity produced by friction.
Antiwrinkling Treatments. Antiwrinkling treatments rely on the use of resins that combine with two or more adjacent molecules of the fibers of cellulosic cloth in a chemical process called cross-linking. (See “Resin Treatments,” pages 321-22.) Cross-linking is what diminishes wrinkling. If a fabric has been subjected to a wrinkle-resistance resin treatment, it may need some ironing after laundering but will tend to resist wrinkling during wear, and any wrinkles acquired during wear will tend to fall out when the article is hung up. Fabrics so treated are referred to by a variety of familiar names: “permanent-press,” “wash and wear,” “durable press,” “easy care,” and “minimum care.”
Because cross-linking weakens cotton fabric, most permanent-press fabrics are cotton/polyester blends. The polyester in the blend is not weakened by the treatment, and treated blends thus have more strength than all-cotton fabrics. (The polyester confers other advantages too. See chapter 22, “The Man-Made Fibers and Blends.”) Some newer treatments, however, cause less deterioration in the strength of cottons, and more durable easy-care 100 percent cottons are becoming more common. These are not yet as strong or as resistant to wrinkling as the blends.
Antiwrinkling treatments are of two major types: precured and postcured. Precured treatments are applied to fabrics before they are sewn into garments, with the result that they may be hard to work with. It is precisely their wrinkleresistant properties that make it difficult for them to contour properly to body shape or to be pressed into creases. Drip-dry clothes have been precured; you hang them to dry and they regain their shape and smoothness with little or no ironing. You see few drip-dry clothes nowadays, however, as most clothes are postcured.
The postcured wrinkle-resistance treatments are applied after the fabric is sewn into garments or other finished products. One problem with postcured treatments is that articles treated with them are difficult to alter: creases, pleats, curves, seams, and the like are built into the fabric’s “memory” and cannot readily be moved around. A second problem is that the crease lines are even weaker than the rest of the fabric: they may lighten or abrade.
The durability of any wrinkle-resistant resin finish depends on a number of factors: the type of resin, the quality and type of application procedure, the degree of saturation, the care used in applying the treatment, and the care of the wearer in following the instructions on the garment label. Resin anti-wrinkling treatments are not permanent, but they are fairly durable, lasting for up to fifty washes. Such treatments usually reduce wrinkling without preventing it entirely; the amount of wrinkling you actually get also depends on such factors as the type and amount of resin used, the skill and care with which it has been applied, and how the garment is laundered and dried.
Antiwrinkling treatments are not applied to synthetics except in blends because many of these fibers have built-in wrinkle-resistance.
There are “durable-press” treatments that create permanent creases and pleats in wool and wool blends. These rely on resin or chemical treatments, and they are of varying durability.
A nonresin wrinkle treatment for cellulosic fibers, without the negative side effects of resin treatments, also exists. The liquid ammonia durable-press treatment, which is used only on cloth that is made of 100 percent cellulosic fiber, involves placing the fabric in an ammonium hydroxide bath in which temperature, fabric tension, time, ammonia concentration, and other factors are carefully controlled. It is a sensitive and expensive process and therefore not widely used. It is fairly durable, lasting for between forty and fifty launderings. The buyer, however, will find no indication on tags that it has been applied.
Wrinkle-treated garments should usually be machine-washed and tumbled dry on the permanent-press cycles. See chapter 4, “Laundering.” But note that the application of antiwrinkling resins has been combined with nanotechnologies to create cloth that is both wrinkle-resistant and stain-repellant. Cloth subjected to such nanotreatments may require significantly different care from cloth that has merely been treated with resins. In such cases, read care labels carefully. See “Nanotechnologies,” below.
Beetling. Beetling is the process in which linen fabric is pounded with wooden mallets until the yarns are permanently flattened and the weave of the cloth is closed. Table linens are usually beetled. Because beetling makes the yarns smoother, it increases luster. Beetling will give linen cloth a uniform thickness and render it more flexible. Ironing with hard pressure renews the flattened look of the yarns after laundering.
Bleaching. Unless it is to be used in its natural color, cloth must be bleached to whiten it or to prepare it for dyeing. Substances used for this purpose include chlorine bleaches—sodium hypochlorite (also used as a household bleach, as in Clorox) or sodium chlorite—hydrogen peroxide, and sodium perborate (the household bleach Snowy or Clorox 2), but a number of other chemicals may be used at various points in the bleaching process. Some Irish linen is still whitened by bleaching in the sunlight, a process called “grass bleaching.” Bleaching by any means generally weakens the cloth to some degree. Sunlight, however, is considerably more gentle than chemical bleaching. Manufacturers sometimes also apply optical brighteners to fabrics, which simply alter the way the fabric reflects light, creating an appearance of brightness and masking yellowish hues. Most all-purpose detergents contain optical brighteners too.
Calendering. The term “calendering” refers to any of several processes in which fabric is subjected to great pressure and/or heat, in a type of ironing using large rollers. Calendering renders fabric smooth and lustrous. It is not a durable treatment when applied to cotton without resins. But when resins are used with calendering to create glazed, ciré, embossed, moiré, or Schreinerized fabrics (see the following paragraph), or when calendering is applied to thermoplastic fibers such as polyester, it is durable.
Crêpeing, Plissé, Embossing, Moiré, Schreinering. The use of heat, pressure, or acids, bases, and other chemicals on textiles can produce decorative effects. Crêpe can be produced either by weaving techniques and yarn construction or by passing fabric between specially engraved rollers. Crêpe produced by engraved rollers will eventually wash out, whereas the former methods render the crêpeing permanent. Embossing and moiré are also done with engraved heated rollers. Embossing produces a design by raising a pattern on the fabric or causing a depression in certain portions of it. It is permanent on thermoplastic fibers but not on cotton unless the cotton is treated with resins that are resistant to water and dry cleaning. Moiré is permanent only on thermoplastic fibers, such as acetate, polyester, and nylon, or on natural fibers treated with resins. Nylon can be chemically treated to crinkle it. The use of sulfuric acid on sheer cotton produces organdy; it stiffens the fabric and makes it translucent. But if the acid treatment is not properly done, it can seriously weaken the cloth.
Plissé (a crêpe effect) is the result of the application of caustic soda (sodium hydroxide). The chemical shrinks the area to which it is applied—mercerizing the area, in effect—and produces puckers. Chemically produced plissé is less permanent than real seersucker, which is produced by weaving. Plissé may come out under ironing, but seersucker will not. Seersucker can be distinguished from plissé by its clearly defined, alternating crinkled rows and smooth rows. By stretching the fabric and seeing how persistent the decorative effect is, you can gain some indication of how permanent it may be.
Embossing. See “Crepeing.”
Emerizing. See “Napping.”
Flame-Resistance Treatments. There are only two flameproof fibers, both inorganic: glass and asbestos. Organic fibers are at best flame-resistant; that is, after the fiber is ignited, flaming is prevented, terminated, or inhibited, whether or not the ignition source is removed. Flame retardants are substances that render fabrics flame-resistant; they slow or stop the eruption and spread of flames but do not entirely prevent burning. Most treated fabrics will extinguish as soon as they are removed from the ignition source. The idea behind flame-resistant treatments is that they provide enough time to extinguish or to escape a fire before grave harm occurs. Wool and silk are naturally somewhat flame-resistant, but various finishes may render either of them less so. Some modacrylic is also naturally flame-resistant. Some synthetics can be rendered permanently flame-resistant during the manufacturing process without the use of flame retardants.
Unless treated, cotton, linen, rayon, acetate, nylon, and polyester ignite and burn readily. In all cases, the construction of the fabric, as well as fiber content, affects flammability; napping, pile weaves, loose weaves, soft-twisted yarns, and light weight all increase flammability.
Prior to the passage of legislation in 1953, there had been tragic fires and injuries caused by highly flammable fabrics and wearing apparel. Some of these involved napped or pile fabrics of viscose rayon that would flash-burn and engulf a wearer in flames in an instant following contact with a spark. The 1953 law, as later amended, prohibits the sale of highly flammable fabrics as apparel but requires that fabrics be flame-resistant only when used in children’s sleepwear, rugs and carpets, mattresses, and mattress pads. Small rugs and carpets need not meet the standards if they bear a label stating, in part, “Flammable … Should Not Be Used Near Sources of Ignition.” Upholstery is governed only by voluntary industry standards. The law on children’s sleepwear requires it to be durably flame-resistant, that is, able to undergo at least fifty launderings without losing its flame-resistant qualities.
Before you take too much comfort in the existence of this limited law, you should know that the test—known as the 45-degree-angle test—for whether a textile is “dangerously flammable” (as provided in the federal Flammability of Clothing Textiles Standard) is widely regarded as inadequate. This test requires, among other things, that you hold a piece of fabric at a 45 degree angle and apply to it a flame of a specified size for one second. If it burns at a certain rate within a certain time, then it is banned for use in apparel in this country. Unfortunately, as one text points out, dry newspaper would not fail this test. Cotton/polyester blends, untreated for flame resistance, are often more dangerous than either 100 percent cotton or 100 percent polyester. Yet such blends are not “dangerously flammable” under the 45-degree-angle test. (They are difficult to treat for flame resistance because the treatments—heavy back-coatings—tend to yield materials with an unpleasant hand.) Moreover, some fabrics pass this test that might melt or emit toxic fumes or suffocating amounts of smoke when exposed to a flame. These characteristics can render them more dangerous than a textile that fails the test and thus legally counts as “dangerously flammable.” Melting synthetic fabrics may adhere to the skin, causing worse burns than flaming fibers; heavy fumes and smoke can be lethal. Better regulations to remove these and other irrationalities, however, are resisted by interests in the textile industry. A proposed molten drop test, for example, that various types of synthetic cloth would have failed (even though they passed the 45-degree-angle test) was dropped.
Flame-resistance treatments have been problematic in other respects as well. One of the flame retardants widely used earlier was subsequently determined to be a carcinogen. A substitute developed for it was then found to be mutagenic. Some flame retardants, when they burned, were found to produce toxic fumes or large amounts of smoke, which were hazards in themselves. Some flame-resistant finishes tend to worsen the fabric’s hand, producing harshness and stiffness, or they weaken the fabric. Excessive dirt can defeat flame retardants, making it important to keep items clean. Bleaches and soaps as well as fabric softeners and detergents containing carbonates (which can build up in fabrics and render it more flammable) should also be avoided.3 All this means that it is important to carefully follow care labels on garments treated with flame retardants. In addition, to reduce the possibility of skin reactions, you should wash articles treated with flame retardants before wearing them.
In 1996, the Consumer Products Safety Commission amended the rule requiring that all children’s sleep wear be flame-resistant, effective as of June 8, 1998. The amendment to the rule, which has aroused fierce opposition, contains two major provisions. First, it exempts from the flame-resistance requirements all sleepwear for infants under nine months of age. Second, it permits sleepwear for children of any age to be made of untreated (non-flame-resistant) cotton so long as it is snug fitting or contacts the skin at all points. (Snug-fitting clothes ignite less easily and burn less readily than loosefitting or flowing ones.) Aside from these two categories, cotton sleepwear must still be treated to render it flame-resistant. So far as I am aware, United States manufacturers no longer make children’s sleepwear that is treated with flame retardants, but some imported cotton pajamas are. In addition, flame-resistant pajamas of synthetic fibers continue to be widely available. But if you find pajamalike cotton garments for children older than nine months that are neither treated to render them flame-resistant nor snug fitting, they will continue to be labeled “Not intended for sleepwear.”
When cotton sleepwear has been treated with flame retardants, this typically is done with tetrakis hydroxymethyl phosphonium (THP) salts, which are said to be both effective and safe from a general health standpoint. Such treatments last for fifty or more launderings. But clothes so treated cannot be washed with chlorine bleach or any product containing chlorine bleach or with ordinary nonphosphate detergents. This can be a problem in those areas that ban phosphate detergents, although there are nonphosphate detergents on the market that state that they will not harm flame-resistant finishes. Unfortunately, THP-treated cloth produces fumes and heavy smoke when it burns.
Nowadays, however, most children’s sleepwear is made of synthetic fibers that have some degree of intrinsic flame resistance—at least for legal purposes (that is, they pass certain tests)—and need no treatment with flame retardants. These include polyester, modacrylic, and, according to its manufacturer, the new synthetic, PLA. There are also inherently flame-resistant variants of rayon, acrylic, and olefin (polypropylene). Experts point out, however, that given the insufficiencies of the legal standard, no matter what you buy, all you can be sure of is that the fabric passed the test, not that the fabric is necessarily safer than another. One authority gives the inherent burning characteristics of fibers as follows, ranking them from most hazardous at the top to least hazardous at the bottom of the list:
Less Safe
COTTON/LINEN
Burns with a hot, vigorous flame, light-colored smoke, and leaves red glowing ember after flaming stops. Does not melt or draw away from the flames.
RAYON/LYOCELL
Burns similarly to cotton and linen, except that it may shrink up and become tighter to the body.
ACETATE
Burns with a rapid flame and melts when burning. May melt and pull away from small flames without igniting. Melted area may drip off the clothing, carrying flames with it. When flames have died out, the residue is a hot molten plastic and is difficult to remove from any surface.
ACRYLIC
Burns similarly to acetate, except that it burns with a very heavy, dense, black smoke. It drips excessively.
NYLON, LASTOL, OLEFIN (POLYPROPYLENE), POLYESTER, AND SPANDEX
Burns slowly and melts when burning. May melt and pull away from small flames without igniting. Melted area may drip off clothing, carrying flames with it, but not to the extent of acetate and acrylic. Residue is molten and hot and difficult to remove. May self-extinguish.
WOOL AND SILK
Burns slowly and is difficult to ignite (especially in winter garments). May self-extinguish.
MODACRYLIC AND SARAN
Burns very slowly with melting. May melt and pull away from small flames without igniting. Self-extinguishes.
More Safe
Glazing. Glazing creates a stiff, shiny appearance. Chintz and polished cotton are familiar glazed fabrics. Older-style glazes of starch or wax are not durable. Some modern glazes are created by baking or calendering resins onto the fabric, and these are more lasting.
Mercerizing. Mercerizing is used principally on cotton yarns and fabrics. They are treated with a solution of caustic soda, causing the fibers to shorten and swell up into a round shape. The effect is that the fabric or yarn becomes stronger, more lustrous, and easier to dye. The fabric also acquires an improved hand and drape. Cotton sewing thread purchased for use in the home should always be mercerized.
Mildew. See “Antiseptics; Mildew Control,” pages 312-13.
Mothproofing. Silk, wool, fur, and other hair fibers are susceptible to damage by insects that feed on the protein in such fibers. Moth larvae eat wool and fur; carpet beetles eat wool, fur, and silk. Wool blends are vulnerable in the same ways that wool is and should receive the same treatment. Insect-proofing that will not come out with laundering or dry cleaning is built into some wool fabrics, such as carpets and upholstery and, apparently, some clothes. Some of these treatments kill the larvae when they try to eat the fibers; others render it indigestible by the larvae. According to one authority, however, none of the substances presently being used for such purposes is completely effective.
Less durable mothproofing can also be applied during dry cleaning. If woolen articles have not been treated, preventive measures should be undertaken at home. See the discussion of mothproofing in chapter 21 on pages 351—52; see also chapter 18, “Closets for Clothes and Linens.”
Nanotechnologies. Nanotechnologies are rapidly being developed that permit new approaches to creating water repellancy and resistance to wrinkles, stains, abrasion, and shrinking. (Nanotechnology is the science of manipulating materials that are only billionths of a meter wide.) Such treatments, it is claimed, can be permanent and often leave the hand and other characteristics of the fabric unaltered. It is hoped that nanotechnologies will also permit improved treatments for, among other things, flame retardance, ultraviolet-radiation blocking, and antistatic effects. “Nano-treatments” involve the application of polymers or other substances at the molecular level in such a way as to cause them to bind permanently to the fibers of cloth, producing the desired effects. In addition, their manufacturers claim, the fabrics remain breathable, and the way it feels to the hand does not change because the nanotechnology attaches to the fabric at a nano- or sub-micron level.
Nano-treated fabrics now available in stores include wool that is washable and resists shrinking; cotton that is stain-, water-, and wrinkle-resistant; and synthetic fibers that are oil- and water-repellant and have enhanced wicking ability. There are also nano-products that are said to improve colorfastness, durability, softness, and drape. (In the case of cottons, new nano-treatments may be combined with older-style resin treatments for antiwrinkling.) Keep in mind that nano-treatments are no guarantee against staining; ink, mud, dyes, mustard, and other staining substances may still stain after nano-treatment. But because the treatment helps keep the stain material on the surface and prevents it from soaking in too deeply, it gives you a window of opportunity for wiping it off before it does much damage. Similarly, water will eventually penetrate items that have been nano-treated for water resistance, but more slowly.
Nano-treated fabrics may need laundering and other care that is significantly different from what you would otherwise give them. Fabric softeners may not be recommended. Dry cleaning may not be recommended. You may need an extra rinse cycle to get good performance; you may be told that steam ironing enhances the performance of the fabric. Always obey the care label on nano-treated fabrics.
Napping; Sueding; Sanding; Emerizing. Napping gives fabrics a fuzzy surface. It is accomplished by giving the yarns from which the fabric is woven a slack twist when they are spun, then passing the woven fabric over a roller covered with wires ending in small hooks. The hooks pull fiber ends out of the fabric and create the fuzziness or nap. (In brushing, brushes are used to raise the nap.) Napping creates air pockets in which warmth can be trapped; thus napped fabrics, such as flannels, are warmer. Napped fabrics are also more stain-resistant because the nap prevents substances from penetrating deep into the fabric. Napping should not be confused with pile, in which additional threads have been woven into the cloth, creating raised loops (which are sometimes cut) on the surface.
Sueding, or sanding, is similar to napping except that the roller that the cloth moves over has a sandpaper surface that abrades the cloth, producing the familiar suede finish. Like napping, sueding can render cloth weaker. In sandwashing, sand is put in a wash bath to abrade and soften the fabric. Emerizing uses gender, emery-covered rollers to produce the sort of suedelike surface you find on many garments of polyester microfiber.
Plissé. See “Crêpeing.”
Preshrinking and antishrinking. Whenever you can, buy preshrunk finished goods. You can usually buy preshrunk fabrics for home sewing as well, but when you cannot you should usually wash them before sewing so as to preshrink them yourself. Unfortunately, continued shrinking of any preshrunk goods may occur, and this shrinking may continue in small increments over many washings.
There are many antishrinking procedures, ranging from simple washing to mechanical, chemical, and resin treatments, and combinations of these. The familiar “Sanforized” trademark indicates that the cloth, woven cotton and rayon, was subjected to a standardized, highly effective method of compressive shrinkage, and that additional shrinkage will not exceed 2 percent. (Compressive shrinkage subjects fabrics to a controlled shrinking process that results in uniform shrinking and ensures that additional shrinkage will not exceed a given percentage.) There are other trademarks reflecting compressive shrinkage and other antishrinking treatments.
Wools are subjected to a similar variety of preshrinking methods using water, chemicals, or thermosetting resin treatments. Fulling is a laundering process to which wool may be subjected to clean it and to produce a controlled degree of felting, or drawing together of the wool fibers. Fulled fabric is smoother and fuller, denser and more compact, which makes it warmer. Thus fulled woolens such as melton (which is a heavily fulled, napped, closely woven fabric) are used to make overcoats. Worsteds are only lightly fulled, if at all. If an antishrinking effect in wool is derived from the use of chemicals, shrinking may develop after several launderings when these are finally washed away.
The “Superwash” trademark indicates that wool has received treatments that render it durably shrink-resistant and machine-washable. The wool is exposed to chlorine, which dissolves fiber scales and reduces felting shrinkage, and then coated with resin. The process makes wool feel different (less appealing, to my taste) and decreases its absorbency. The use of chlorine in the process raises environmental issues.
Resin Treatments. Textile resins are “pre-polymers” that are applied to cellulosic fibers (cotton, linen, rayon) or blends containing them to produce a variety of effects: permanent creases or wrinkle-resistance, resistance to shrinkage, permanent stiffness or crispness, shine or luster, water repellancy, and decorative effects such as ciré, moiré, embossing, and so on. The resins most commonly used for these purposes are urea, glyoxal, carbonate, and melamine formaldehyde compounds. Resins work not by coating the fibers but by linking adjacent cellulosic molecules so that the resins actually form part of the structure of the cloth.
When resins were first used, years ago, health questions were raised about them because they were found to emit formaldehyde fumes. The odor was often unpleasant; some people are allergic to formaldehyde or can become sensitized by it; formaldehyde is classified as a “probable carcinogen” by the EPA. Newer, lighter application procedures and low- and non-formaldehydeemitting resins, however, have by and large answered these concerns. (Newer resins still emit an extremely low amount of formaldehyde, but documented cases of sensitivity to resin-treated cloth in this country are rare.) Various experts seem to agree that resin-treated cloth is safe, recommending simply that you launder resin-treated articles once before using them to remove the tiny amount of free formaldehyde they may contain. There are also resins that contain no formaldehyde, which are often used on infants’ and children’s wear (because younger folk are more sensitive), but these tend to be more costly and less effective.
The application of resins, however, is not without other side effects, bad and good. On the negative side, they will render fabrics less absorbent, which means they are less comfortable, particularly in hot, humid weather. The cloth will also have a less pleasant hand and be weaker—up to 50 percent weaker—and less resistant to abrasion. Treated cloth will also develop a tendency to oil-stain, just as synthetic fibers do, and may develop static cling. Resin-treated fabrics may require different, milder laundry treatments. (See chapter 21, “The Natural Fibers,” pages 349-50.) On the other hand, besides reducing shrinking and wrinkling, resins will cause the cloth to dry faster and will act as a stiffener, which renders many cotton garments more attractive. And both the positive and negative side effects of resin treatments are reduced by newer resins and lighter applications.
See also “Antiwrinkling Treatments,” pages 313-14.
Sanding. See “Napping.”
Schreinering. See “Crêpeing.”
Skin Protection from Ultraviolet Rays. More protection is naturally provided to your skin against the ultraviolet rays of ordinary sunlight by clothes that are made of thicker, tighter weaves. Darker clothes are more protective than lighter-colored ones (although they feel hotter) because they absorb more ultraviolet radiation. Dry clothes are more protective than wet ones because the latter are more transparent. As far as cloth construction and color go, therefore, in warm weather you have something of a Hobson’s choice between comfort and protection.
Some fabrics are manufactured to provide extra protection from the dangerous rays of the sun, through chemical treatments—called “sun-protection” or “ultraviolet (UV) blockers”—or cloth construction or a combination of these. Such cloth tends to be fairly light and cool yet offers at least as much protection as dark, tight weaves. Check hang tags and labels to see whether garments have received sun-protective treatments. See also chapter 13, “Fabrics That Work,” pages 183-84.
Soil-Resistance Treatments. Apparel, tablecloths, upholstery fabrics, and other textile goods used in the home can receive treatments or finishes that make them more accident-proof and soil-resistant. Soil-resistance treatments are of two types: soil release and soil repellant. See also “Nanotechnologies,” above, on new soil- and stain-resistance treatments using nano-treatments.
Soil Repellants. A soil-repellant fabric has received a treatment that renders it resistant to soil by causing water and/or oil to bead on its surface rather than penetrate immediately. This gives you a chance to wipe dirt and spills off before they can do damage. Such treatments are now available for both wool and synthetic carpets. There are many different kinds of soil repellants, and they do not all do the same thing. Some repel only water. Fluorocarbon polymers such as Scotchgard Dual-Action and Zepel repel both oil and water. Soil repellants generally will reduce the absorbency of fabrics but not their breathability. Soil-repellant treatments are applied to both natural and synthetic fibers as well as their blends.
Soil release. Soil-release fabrics have received a treatment that causes them to come cleaner during laundering. Check labels and hang tags to see if an article has received a soil-release treatment, e.g., Visa, Come Clean, or Scotchgard Stain Release. Soil-release treatments are applied only to synthetic fibers and their blends or to durable-press fabrics—that is, to oleophilic/hydrophobic fibers or to those that, as a result of resin treatments, resist thorough wetting, and thus thorough cleaning, during laundering. Without soil-release treatments, any of these fabrics may need some laundering pretreatment to ensure against “ring around the collar (or cufí)” or to help remove soil in areas of the garment that are particularly likely to pick up body oils or greasy food stains, such as collars, cuffs, and the midriff area.
Soil-release treatments are not all the same. Fluorocarbons work by making a film that prevents the oil from making direct contact with the fibers, so that a detergent-and-water solution can more easily wash it away. Others work by trying to make the surface of the fabric more hydrophilic through the application of chemicals. According to one textiles authority, those soil-release treatments that create a more hydrophilic fabric surface have various beneficial side effects: they can improve the garments’ comfort level by increasing their moisture takeup, soften the hand, reduce static buildup, decrease soil redeposition during laundering, and reduce pilling. This expert points out, however, that soil-release treatments actually seem to cause fabrics to soil more heavily than nontreated ones. Soil-release treatments have varying degrees of durability; some will last the life of the garment.
Combination soil-repellant and soil-release finishes. Note that the application of fluorocarbon copolymers (Scotchgard and Zepel) renders fabric both more soil repellant and more soil releasing.
Stiffening. Cottons and linen may be given temporary stiffness or crispness by the use of starches or sizing. These terms are often used interchangeably, but “sizing” should properly refer to any substance used to stiffen a fabric, and “starch” only to starch solutions, that is, solutions containing C6H10O5. A wide variety of substances may be used for temporary stiffening—from starch to resins. Starches tend to be crisper and sizings softer. Both will wash out and, if the original crisp look and feel are to be retained, must be replaced on laundering. Overstarching or oversizing may be used to conceal inferior goods. If goods after washing become hopelessly limp, they may have been overstarched. If you suspect overstarching, before you buy the garment, rub the fabric between your hands to see whether any starch will powder off. (For a discussion of starching or sizing at home, see chapter 6, “Ironing,” pages 111-12.)
Many more or less permanent stiffening treatments are also in use. These work by altering the structure of the fiber with resins. The application of resins has a variety of side effects, good and bad. See “Resin Treatments,” above.
Sueding. See “Napping.”
Water-Resistance Treatments. Fabrics that are absolutely impermeable to water are called waterproof. Those that are called water-repellant have a coating of some hydrophobic chemical that causes water to bead up on their surface rather than soaking through immediately. These fabrics have varying degrees of resistance to water but sooner or later are penetrated. Waterproof articles are made of or coated with a continuous layer of some water-insoluble material such as plastic, rubber, vinyl resins, and the like; thus they are impermeable to air as well as water. Waterproofing is generally permanent. Waterrepellant treatments, however, have varying degrees of durability. Some lose their effectiveness with washing or dry cleaning or both. Durable water-repellancy treatments are possible using any of a number of chemicals and resins that will withstand both laundering and dry cleaning. Many of them confer other advantages such as wrinkle-resistance and stain resistance. Silicone treatments, while economical and highly effective, do not launder as well as they dry-clean. Fluorochemical water-repellants, such as Scotchgard or Zepel, which also function as soil repellents, to some extent repel oil as well as water. When water-repellant garments become less effective as a result of cleaning or washing, they may be retreated by the dry cleaner. Labels and the occasional knowledgeable sales clerk are your only sources of information about water-resistance treatments.