Garment-finishing techniques.pdf

Garment-finishing techniques S. MacA. Fergusson 15 RMIT University, Melbourne, VIC, Australia 15.1 Introduction Typically, casualwear and sportswear are the major products being produced by several garme...

Garment-finishing techniques S. MacA. Fergusson 15 RMIT University, Melbourne, VIC, Australia 15.1 Introduction Typically, casualwear and sportswear are the major products being produced by several garment manufacturers. Today, the garment manufacturers are facing harsh competition due to the global economic crisis, stricter regulations in international trade and the stiff rise of the prices of raw materials and chemicals (Nadvi et al., 2004; Ramaswamy and Gereffi, 2000). Apparel manufacturers have to produce a diverse product mix as consumers are difficult to understand and predict (Deaton, 1980). Con- sumer’s choice is shifting from traditional designs towards luxury high-fashion items. Almost all consumers demand both moderate pricing and frequent style changes (Ulrich et al., 2003). The frequent style changes provide new challenges for the manufacturers in their efforts to fight for the dwindling consumer dollar. The garment-finishing processes can assist to a certain extent to fulfil the requirement of fast-moving fashion and to add functionality. Garment finishing consists of a series of finishing operations performed in the garment to improve its aesthetics, handle and functional properties. The processing operations can be either or both mechanical and chemical in nature, which are per- formed in stitched garments as single or batch. Several finishing techniques applied to the fabric can be applied to manufactured garments. However, specialty machines are needed for garment finishing operations. In addition, many of the finishing oper- ations may not be economical to perform in garment form. Hence, it is imperative to complete the finishing operations in fabric form unless there are unique features that can only be added in the garment form or incorporation of any functionality to the garment. The term ‘garment finishing’ was a buzzword for the process in the denim industry; now the term has been extended to a range of ready-made garments such as shirts, T-shirts, trousers and jackets and even to all other types of clothing. Various chemicals are used for value addition to garments through effects including various feels such as soft, supple, dry feel, bouncy feel; and to adding functionalities such as water/oil repellency, wrinkle free, moisture management, stain protection and durability to the garment. Garment dyeing, one of the finishing operations, allows the manufacturer to pro- duce special colour effects that may not be feasible from continuous processed fabric. The demand from retailers for rapid response to fashion and colour changes has resulted in some speciality garment manufacturers producing products that can meet these requirement using fabric that has been previously prepared for dyeing when Garment Manufacturing Technology. http://dx.doi.org/10.1016/B978-1-78242-232-7.00015-1 Copyright © 2015 Elsevier Ltd. All rights reserved. 388 Garment Manufacturing Technology the garment is made. The made-up garments are then processed to their respective col- ours by specialised garment dyers. Thus, short runs of a specific product are therefore possible with the advantage of more economical garment production when only an uncoloured fabric is being used. This reduces wastage and lowers the cost of stock, when only a single fabric type is required. In addition to the garments prepared from woven fabrics, knits (especially single jersey and interlock) are also the major products suitable for garment finishing. The garments prepared from traditional natural fibres or their blends can be suitably processed in garment form. Some specialty fabric types such as blends of wool/nylon and wool/cotton have recently been processed in garment form in order to meet specific market demands of comfort and performance. The traditional process of pressing is still the dominant operation in almost all the garment manufacturing units, which adds aesthetic value to the garment and improves the attractiveness of a garment at the point of sale. However, the recent technical advancements have assisted in the garment finishing techniques to achieve improved functionality and/or to create customised garments. This chapter covers the garment- finishing techniques that are recently being used by the manufacturers. The finishing techniques performed by mechanical and chemical means, which are used for garments made from various fibres, are discussed. An overview of denim product fin- ishing and the pressing method are also given. 15.2 Garment finishing for functionality The sequence of operations and various types of garment-finishing techniques are dis- cussed in the following section. 15.2.1 Sequence of operations There must be a logical sequence in the finishing of garments so that they are presented to the consumer in the best possible condition. The following operations should be followed to ensure that all possible mistakes are being removed prior to garment finishing: 1. Careful visual inspection of the garment for sewing faults, loose threads, untidy seams, uni- form positioning of buttons, etc. Loose threads may become entangled in machinery during wet processing or pressing; these should be attended to prior to further operations. 2. Performing the necessary garment-finishing operations followed by the subsequent steps (if any) needed for adjusting the chemical formulations. 3. Wet processing of the garments for structural relaxation or to remove any residual chem- icals or any visible stains acquired during the making-up process. During this processing step, it is possible to carry out some chemical treatments to enhance the garment feel or performance. 4. Tumble-drying of the garments, which assists in further relaxation. 5. Final pressing and packaging. Garment-finishing techniques 389 15.2.2 Permanent crease and wrinkle-free treatments Garments made from 100% cotton e particularly trousers, slacks or pleated skirts e may require the addition of a suitable permanent pleat treatment (Kang et al., 1998). If the fabric has already been treated during manufacture with the necessary chemical, that is DMDHEU (di-methylol dihydroxy ethylene urea), the processing route is relatively simple; however, it must be remembered that the resin treatment has not been cured and therefore no wet treatment can be applied to the garments prior to the fixation stage (Wei and Yang, 1999). The necessary creases are applied to the garment by hot-head pressing at a temperature of at least 150  C. The pressed garments are then given a heat treatment for 5 min at 150  C in a suitable oven. Following this treatment, if necessary, the garments can be washed to remove any stains and given a final pressing. If the treatment is required on garments made from cotton, linen or viscose, the appropriate chemical, usually DMDHEU, can be applied by using a robotic spray sys- tem that utilises a spray machine with two robotic arms and two mannequins, allowing higher production to be achieved (e.g. Picasso SS330, VAV Technology GmbH). This system ensures that the chemicals are applied uniformly to all parts of the garment. Garments can then be dried, hot pressed and the resin treatment cured as previously outlined. Finally, the garments may be rinsed in warm water to remove any unreacted resin, hydro-extracted, dried and finish-pressed. This system is ideally suited for the application of easy-care finishes that may be required for specific end-uses where the chemical has not been previously applied at the fabric-manufacturing stage. Surface finishes such as stain release and softeners may also be applied using this technology. Similar processes can be adopted for wrinkle-free finishing, where the chemical treatment helps in the better recovery from creasing. The finishing chemicals can help to achieve crease recovery, dimensional stability, reduced pilling and particularly with knit goods and improved appearance after several washes. To achieve a good result in finishing, it is absolutely essential that the garments are well prepared, and that the recipes and processes are strictly followed and exactly monitored. 15.2.3 Water/oil repellent treatment Hydrophobic properties are achieved by the application of the water/oil repellent treat- ment to the substrates (Bahners et al., 2008). The main product groups for this treat- ment are: (1) metal salt paraffin dispersion, (2) polysiloxane and (3) fluorocarbon polymers. The surface of the substrates must be covered with molecules in such a way that their hydrophobic radicals are ideally positioned as parallel as possible, facing outwards, during the chemical finishing with these products. Metal salt paraffin dispersions (such as aluminium) are products positively charged due to the trivalent aluminium salt, which produces a counter-polar charge on the fibre surface. Polysiloxanes form a fibre-encircling silicone film with methyl groups perpen- dicular to the surface. The hydrophobicity of the finish is affected by the film formation 390 Garment Manufacturing Technology and direction of the methyl groups. Fluorocarbon polymers also form a hydrophobic film where the fluorocarbon radicals are perpendicular to the fibre axis, which prevents wetting of the fibre surface. The extremely low interfacial tension of the fluorocarbon chain towards all chemical compounds is responsible for its high hydrophobic and oleophobic properties. 15.2.4 Antimicrobial treatment Different types of antimicrobial finishes used in other areas such as food preservatives, disinfectants, swimming pool sanitisers or wound dressings, can also be used for tex- tiles (Gao and Cranston, 2008; Joshi et al., 2009). The antimicrobial finishes are potent in their bactericidal activity, which is indicated by the minimal inhibitory concentra- tion values (Nayak et al., 2008). However, repeated laundering of the textiles leads to the gradual loss of the biocides. In addition, their attachment to the surface of a textile or incorporation into the fibre substantially reduces their activity and limits their availability. Due to these reasons, the finishes need to be applied in large amounts to the textiles to sustain durability, for effective control of the bacterial growth. Different chemicals such as organic compounds (amines or quaternary ammonium compounds, biguanide, alcohols, phenols and aldehydes), mineral compounds (metal ions, oxides and photocatalysts), organometallic compounds and natural compounds are used for antimicrobial finishes (Nayak and Padhye, 2014a; Simoncic and Tomsic, 2010). 15.2.5 Flame-retardant (FR) finish Flame-retardant (FR) finishes are essential to reduce flame propagation, hence to achieve FR properties (Horrocks, 1986; Tesoro et al., 1972). The FR finishing of fabrics can be divided into wash-resistant or non-wash-resistant finishing, depending on the end-use application. In the case of garments, FR finishes that are non-durable can be applied to avoid the constraint in the application techniques involved. Although these non-durable finishes are fast to dry-cleaning, they are not fast to repeated laundering. 15.2.6 Enzyme washing or bio-polishing The application of enzyme treatments on cotton and regenerated cellulose materials such as lyocell (TencelÒ) has become widely accepted (Harnden et al., 2001; Nostro et al., 2001). The process referred to as bio-polishing has the advantage of preventing pilling, as the enzyme “cellulase” hydrolyses the loose surface fibres on the yarns, causing them to break off and thus leaving a smoother, more uniform fabric. A softer fabric with improved colour brightness is also achieved by this technique. Enzyme treatments are important for the finishing of lyocell, which was invented in 1991 and is sold under the trade name TencelÒ, manufactured by Lenzing. This fibre has a tendency to fibrillate when the fibre is wet. These fine fibrils on the surface tend to peel up and if not removed, show as pills on the fabric surface. Cellulase treatments also enhance the surface features of the fabric, giving it a smooth, silky appearance. Garment-finishing techniques 391 Treatment temperatures range from 50 to 60  C and pH ranges from 4.5 to 6.5 depend- ing on the severity of effect required. The application of a protease treatment to silk was introduced as an alternative to the degumming process using alkaline soap solutions (Freddi et al., 2003; Gulrajani et al., 2000). Alkaline soap has a deleterious effect on the silk, resulting in a harsh feel to the material. Enzyme degumming with protease removes the sericin without damaging the fibre. Results of enzyme treatment have shown that the fibre is stronger than that obtained by traditional alkaline soap treatments. Cheng et al. (1998) reported on the enzyme washing of silk “crepe de Chine” fabric using commercially available protease. This work showed that the degree of surface change to the fabric surface was dependent on the enzyme-dosage level. The higher the dosage, the greater the damage to the fabric, and thus a lowering of fabric strength and an increase in surface fuzziness. Protease treatments for wool garments were intro- duced during the early 1990s. This treatment modifies the surface protein of the fibre and as a result reduces the surface fibre and thus reduces the tendency for pilling to occur. 15.2.7 Garment dyeing In garment dyeing, fully fashioned garments such as pants, sweaters, shirts and skirts are dyed after manufacturing is completed (Partridge, 1975). Most garments are made of cotton or a cotton-rich blends which may contain other fibres such as wool, nylon, silk, acrylic, or polyester as a minor component in the blend. Traditionally, garments are manufactured from pre-dyed fabrics before the cutting and sewing. Garment dyeing has been gaining importance and popularity due to cost savings and fashion trends in recent years, and will continue to grow in the future (Bone et al., 1988). A major drawback of garment dyeing is the risk of maintaining a large inventory of a particular style or colour in today’s dynamic marketplace. Two types of equipment, namely paddle machines and rotary drums, are generally used for garment dyeing. Paddle machines gently move the garments using paddles similar to a paddle-wheel on a boat. A high liquor ratio is required for paddle ma- chines, and they may have limitations in shade reproducibility. On the other hand, rotary drums work on the principle of stationary liquor and movement of the material. These machines are sometimes preferred for garments such as sweaters, which require gentler handling. For dark shades it is normal to use reactive dyes in the dyeing of 100% cotton gar- ments. This can pose significant problems in relation to fastness of the finished garment, particularly performance to wet treatments such as washing and perspira- tion if the hydrolysed reactive dye is not completely removed. Traditionally, garment dyers used after-treated direct dyes for both pale and dark shades. Pale shades were after-treated with a cationic resin compound such as Tinofix ECOÒ (Huntsman Chemicals). Dark shades were often dyed using after-coppered direct dyes that would give adequate wet-fastness properties. Customers require their garments to be washable under particularly variable condi- tions, that is from ambient (25e30  C) to hot (40e60  C) temperatures, depending on the domestic washing machine employed. Reactive dye will in general meet the 392 Garment Manufacturing Technology demands of high wet fastness. Liquor ratios in garment dyeing vary from about 20:1 to 30:1, as large amounts of electrolyte are required to achieve adequate exhaustion; which can create some environmental issues. The need to remove the hydrolysed dye (dye attached to the fibre surface but not chemically bound to the fibre) can create some problems in the soaping operation. As a general rule, the most appropriate product for soaping reactive dyes is a protective colloid based on sodium polyacrylate. This chemical will remove the hydrolysed unfixed dye from the fabric and hold it in solution ready for discharge to effluent. Some fabric blends can be a problem; for example, the dyeing of a cotton wool blended fabric where the wool portion is only about 10%e15%. In such a case, the pH of the dyeing must not exceed 8.0. In reactive dyeing, the pH of the fixation step is usually about 10e10.5 and is achieved using sodium carbonate and a temper- ature of 60e70  C. A lower pH of 8.0e8.5 can be used, but the dye bath exhaustion would be lower. This lower pH will not damage the wool to the same extent. After- coppered direct dyes may in fact be more suitable for such a blend, giving good light and wet fastness. 15.2.8 Other functional finishes for garments Often, garment finishing includes softeners, soil-release finishes and finishes for ultra- violet (UV) protection. Softeners can alter the handle of the garment, and the degree of softness depends not only on the chemical character but also on their position in the textile. Soil-release finishes facilitate the removal of stains from various fabrics that usually show some resistance to stain removal by normal cleaning processes. The UV finishes ensure that the clothes reflect the harmful rays of the sun, reducing a per- son’s UV exposure and protecting the skin from potential damage. Not all garments may require wet processing. Some customers request that gar- ments are washed prior to pressing in order to develop the specific handle required. During wet processing, additional chemical finishes can be added to enhance garment properties such as handle modifiers, antimicrobial materials and non-stain or comfort- enhancing products. In subsequent processes following washing, the garments can be dried by commercial dryers. Drying of the garments is a two-step process. The first step is removal of excess moisture that is not chemically bound to the fibre. Several methods are available; these include squeeze rollers or mangle and hydro-extraction (spin-driers). The squeeze- roller or mangle method is no longer popular due to excessive creasing that may be introduced into the garment. Hydro-extraction, while not a continuous process, is very efficient at removing the water trapped between the fibres within the yarns. Following the removal of excess moisture, the second stage is to tumble-dry the garments. Temperature of tumble-drying should not be excessive so as to cause yellow- ing of the fibre, particularly in pale shades. Some fabrics may be treated with handle modifiers at the manufacturing stage; some of these handle modifiers are sensitive to temperature and may cause shade changes to occur. Temperatures of 60e75  C should be considered as a maximum. Garment-finishing techniques 393 15.3 Knitwear finishing The finishing of knitwear garments requires special attention to processing, as this will ultimately result in improved quality. The knitwear sector consists of a range of fibre and fibre blends. Wool is still possibly the most important section of knitwear production, followed by 100% acrylic and wool acrylic blends. Mohair, alpaca and cashmere have all figured into the production of knitwear, but essen- tially their production is relatively small compared to both wool and wool acrylic blends. Prior to the introduction of the Shima Seiki whole-garment knitting machine, the majority of finishing operations took place prior to final garment making up. That is, the garment bodies, sleeves, etc. were finished separately to overcome dif- ferences in relaxation due to varying tensions that might have applied during the knitting stage. The finishing process can be divided into two sections, wet finishing and dry finish- ing. Dry finishing can also be described as steam finishing. In more recent times, sol- vent finishing has been used for the treatment of wool knitwear materials. In relation to the different types of yarns used in manufacture each of these processing methods will be discussed. 15.3.1 Dry finishing The final steaming operation is the key to attractive product presentation to the customer. During final pressing, creases should be removed and the garment checked for size (see Section 15.5 for detailed information on pressing). During crease removal, excessive stretching should be avoided, as this could result in shrinkage at the first wash. Whilst hand-held irons may be used, the most appropriate system is a flat steam- ing table that incorporates a vacuum system that will cool the garment quickly after steam application. The Hoffman-New Yorker SBT knitwear steam table provides the knitwear finisher with a versatile manual steaming and vacuum table; or alterna- tively the Hoffman-New Yorker SBTA automatic model can be used. The finisher can be assured of producing a quality garment from the use of this equipment. The Woolmark Company (Australia) can supply extensive practical infor- mation on the processing of all types of wool garments. 15.3.2 Wet finishing Where woollen spun yarns are used in the knitting process, it is necessary to remove the lubricants used during the spinning operation by scouring or washing. Other con- taminants from manufacture may also be present; these include floor dirt and machine lubricants. The scouring or washing process also brings about relaxation of the knitted loops so that a stable garment is produced. Woollen yarns may not be manufactured from non-shrink or washable wool, and therefore careful attention must be observed in the wet processing so as not to cause excessive shrinkage. 394 Garment Manufacturing Technology Smith drums (Figure 15.1) are ideal for washing due to low mechanical action on the garments. For milling shrinkage, the most appropriate machine is a barrel washer (Figure 15.2), which will give increased mechanical action to promote consolidation and surface cover. The typical conditions discussed below can be used for the wet finishing of knits prepared from wool. Typical washing conditions at 40  C Liquor to material ratio 30:1 Suitable detergent 0.5 g/L Wash gently for 5e10 min Rinse two cycles at 40  C. If further consolidation, that is milling shrinkage, is required, this can be accom- plished in a separate bath at 40  C as follows: Liquor ratio 30:1 0.3 g/L non-ionic detergent Wash 5e30 min depending on the degree of surface finish required Drain the bath and rinse well at 30  C Hydroextract and tumble-dry. Figure 15.1 Smith drums used for wet finishing of wool. Garment-finishing techniques 395 Figure 15.2 Barrel Washer used for increased mechanical action. Unlike woollen yarns, worsted spun yarns contain only minimal quantities of lubri- cants, and therefore the finishing treatment can be less vigorous. Relaxation of the ten- sions produced in knitting is important to prevent relaxation shrinkage of the garment on initial washing by the consumer. Relaxation can be accomplished either by wet fin- ishing or by simply steaming the garments. If wet finishing is to be undertaken, a similar process to that described for woollen knitwear can be adopted. The mechanical action during the washing stage should be minimal: a short run for 1e2 min followed by soaking would suffice. A Smith drum or overhead paddle would be suitable ma- chinery. The washing procedure is described below: Water at 40  C, liquor ratio 30:1 0.1e0.2 g/L suitable detergent Run 2 min, stand for 10 min Rinse well in warm water Tumble-dry. 15.3.3 Solvent finishing Solvent processing was introduced by manufacturers to reduce water and effluent charges. The basic process is similar to dry-cleaning and now uses perchloroethylene (Perc) as the solvent medium rather than the traditional Stoddard solvent. During the process a small amount of water is added with the detergent system to assist in the removal of water-soluble contaminants. The system is totally enclosed and all the sol- vent is recovered by distillation. 396 Garment Manufacturing Technology 15.4 Denim garment finishing In denim manufacturing, it is an amazing fact that one style of jeans is converted into different colours, which is achieved by garment washing. In today’s denim manufacturing, many denim finishes are done to give the jeans a broken-in look, much like what unwashed (dry denim) denim looks like after it has been worn many times. There are two main types of garment washes for denim: chemical and mechanical. Various chemical finishes such as bleaching, enzyme washing and acid washing are the major types of chemical finishing used for denim. The bleaching is performed to discolour the denim in specific locations. The degree of bleaching action depends on the strength of the bleach, temperature and duration of the treatment. The environ- mental friendly finishing process ‘enzyme washing’ is used to create prominent effects at seams, pockets and hems (Koo et al., 1994; Heikinheimo et al., 2000). More recently, a range of enzyme treatments have been developed by AB Enzyme GmbH specifically for the treatment of denim garments. ECOSTONEÒ is the registered trade- mark of this bio-polishing process developed by AB Enzyme GmbH. The advantages of the enzyme process are: Improved abrasion, colour removal without damaging the fabric strength Simple and easy treatment Environmentally friendly Greater variety of effects are achievable Shorter washing times. BIOTOUCHÒ is another range of products developed by the same company for the treatment of materials made from cotton, linen, viscose and their blends with other fi- bres such as polyester or nylon. Garments treated by this process have smoother sur- face properties, are pill free and as a general rule have better drape and a softer handle. Acid washing is also known as stone washing, which is accomplished with pumice stones. Due to severe abrasive action, surface fibre damage occurs. In some instances the pumice is impregnated with potassium permanganate (an oxidative bleaching agent), this chemical being less damaging to the cotton fibre than sodium or calcium hypochlo- rite. Following this bleaching and stone washing, the garments are washed with sodium bisulphite (reducing agent) to complete the removal of the brown colour generated by the permanganate wash. This treatment has the effect of surface bleaching the indigo as well as giving the garments a softer handle and creating a distressed look. Mechanical denim finishing includes the process of stone washing and micro- sanding. Mechanical stone washing is similar to the chemical washing process of the acid wash. Here also stones are tumbled with freshly dyed denim, but it does not require any chemicals. The final look of the product depends on the size, shape and hardness of the stones used. In several instances the metal buttons and rivets get damaged due to the mechanical action. There are three types of micro-sanding: sandblasting, machine sanding and hand sanding. The sandblasting process is the most common, which is accomplished by passing a very abrasive substance through a nozzle at the denim at high speed and pressure that creates many different patterns Garment-finishing techniques 397 Figure 15.3 Example of X-Burner technology. in the denim. Machine sanding is performed by using a machine (similar to the machine used to sand down wood furniture), whereas hand sanding is done with a fine-grain sandpaper by hand. The most recent development in the processing of denim has been the use of laser technology to imitate the human hand. VAV Technology GmbH produces the X-Burner system, a dry method of producing patterned effects on denim. Figure 15.3 illustrates the effects available using the X-Burner technique. This system allows a wide range of effects to be produced efficiently with minimum damage to the fabric. The VAV Technology for automated denim processing increases productivity, unifor- mity and quality of the finished product. 15.5 Pressing (factors and equipment) Garments are pressed to remove any creases, and present the garment to the customer in attractive condition suitable for sale. Garment presentation to the consumer is a vital step in the finishing of a product. The opinion of the customer is an integral step in brand recognition. Poorly presented product will have a detrimental effect on the brand’s quality and therefore product saleability. A badly creased garment will lower its retail value and thus the manufacturer’s sale margin. Pressing therefore 398 Garment Manufacturing Technology is an important step in the production process. Pressing should accomplish the following: Removal of all manufacturing creases and wrinkles Clarity of pleats if there are pleats present (such as in skirts and trousers) Uniformity of collars and cuffs if present Stabilising the garment, particularly in the case of wool knitwear to retain the desired shape Relaxation of any stresses induced during garment manufacture. 15.5.1 Factors affecting pressing In order to achieve good pressing quality, there are four basic parameters that need to be controlled to meet optimum performance: heat, moisture, pressure and cooling with vacuum. The importance of each parameter is discussed in the following section. Heat is required in most pressing operations to enable the fibres to soften and thus stabilise the garment shape. Temperature selection is of utmost importance, as an incorrect temperature setting can cause damage to fibres and yarns. Moisture is introduced by the use of steam. Steam at different pressures has different moisture contents; the higher the steam pressure, the lower the moisture in the steam. The presence of moisture is required to aid in fibre swelling and thus shape stabilisation. Different fibres require different amounts of moisture. For example, natural fibres such as cotton and wool and regenerated cellulose fibres such as bamboo viscose and viscose rayon require the presence of moisture in the steam, and therefore steaming tables are usually preferred. On the other hand, synthetic fibres require heat to promote swelling and therefore relaxation of the structure. Excessive moisture may cause fabric shrinkage and colour bleeding. Pressure is applied to the garment during pressing to give good crease retention and permanency. Excessive pressure may result in garment or crease distortion. Vacuum is applied at the completion of the pressing operation. This draws cool air through the garment, reducing the garment temperature, lowering the moisture content and increasing shape retention. Particularly important for garments made from wool and wool blends, this also applies to cotton and viscose blends with synthetic fibres such as polyester and nylon. 15.5.2 Pressing equipment There is a large range of equipment available for the pressing of garments, from the simple hand steam irons to the sophisticated vertical front (BRI-1400/101) and back pressing robot manufactured by the Viet Group (Figure 15.4) for the pressing of jackets. The development of this machine has the advantage of making the pressing operation more pleasant for the operator as well as reducing the skill level required. In the operation of this sophisticated equipment, the jackets are loaded onto the pressing former automatically and remain on the hanger at all times during the oper- ation. As the human body is three dimensional, both the front and the back of the garment are pressed while the jacket is hanging on the body former. In this position it hangs as if on the human body, thus making the alignment of seams easier. Since Garment-finishing techniques 399 Figure 15.4 BRI-1400/101 pressing robot. the jacket is in the hanging position during the pressing operation, the lining is in the most appropriate position for even pressing. As the garment is always in the hanging position there is even pressure applied dur- ing pressing. The design of the body form is such that there is little chance of the garment moving during pressing. This improves quality and consistency of the final product. The operator is always in the vertical position rather than being bent, so there is little danger of injuries occurring. Figure 15.5 shows the BRI 1200/101 jacket front Figure 15.5 BRI-1200/101 jacket front finisher. 400 Garment Manufacturing Technology Figure 15.6 Veit 8326 shirt finisher and Veit 8900 shirt press. finish pressing. Similar to the BRI-1400/101 (Figure 15.4) machine, the jacket hangs on the former so that the alignment of the edges and seams is made easier for the oper- ator. For shirt finishing, two high-performance machines have been developed by the Veit Group: the Veit 8326 shirt finisher and the Veit 8900 shirt press (Figure 15.6). Special attention is given to the position of the hem and the sleeves, to ensure that the shirt is finished in optimum condition. Excessive stretching of the hem is avoided by the specially developed hem-tensioning device. The advantages of this machine are: Shorter cycle times Increased energy savings Lower radiant heat to the surroundings Automatic unloading. The UADD B58 automatic left and right front jacket press from Hoffman Machinery Co. is fitted with a unique 40-program micro-processor control. The unique feature is automatic fine-pressure control with 2-psi increments. It is possible to connect the micro-processor to a PC network in order to monitor production. In addition to the above automated machines, hand irons are the most common type of pressing equipment used by households. These irons are heated electrically with the provision of steam supply and temperature control. There are various shapes of the irons and the weight ranges from about 1 to 15 kg. There are several types of pressing tables available for these irons, which may include a simple table or a table with vac- uum arrangement to hold the garment or section of a garment in place and dry after pressing. Additional parts can be attached to the table to support various parts of a garment so that a suitable shape is available for each part. Steam presses are used to assist in better shape retention and improve the effi- ciency of pressing. The steam presses can be of various shapes with automatic oper- ations. There are provisions of stem supply to all the parts, vacuum and altering the pressure. Some designs can be fitted with a programmed logic circuit to work in varying cycles depending on the type of garment. In some designs, additional extensions such as bucks or matching heads can be attached when the shape of the garments changes. Many other types of pressing equipment are available that will Garment-finishing techniques 401 enhance the final quality of the garments produced. Depending on the type of product being produced, different equipment will be required. Some examples include carousel press, specially designed press for trousers and skirts, a steam air finisher and a steam tunnel. Specially designed machines are available for creasing and pleating. Creasing equipment is used to press the edges of clothing components so that they are easily sewn. For example, the cuffs and patch pockets are formed into shape by the working aid, and are pressed to retain the shape, which makes the sewing operation easier. Pleating machines create a series of creases following a specific pattern or randomly, depending on the type of the cloth. Pleats of various lengths can be prepared by hand or by using machines. Blade-type and rotary-type machines can be used for rapid and ac- curate pleat creation. In all the above pressing equipment, it is essential to precisely control the variables so that all the components or finished items are subjected to same conditions to avoid vari- ability. The technological developments for accurate sensing, pressure monitoring and measuring the strength of a cooling vacuum can assist in avoiding the variations. Hence, garment manufacturers should adopt the automatic units to achieve consistent results. Some garments are manufactured as wash-and-wear or permanent-press garments. These clothes are prepared by special finishing treatment to provide crease-resistant properties. For example, the resin treatment of 100% cotton items can provide crease resistant properties at the expense of loss in strength and abrasion resistance. The man- ufactured garments can be treated with the speciality chemicals by dipping in the chemical, spraying and vapour phase treatment. In the former two cases, the garment needs to be cured after application of the chemicals. Incorrect selection of parameters during pressing can lead to shrinkage, colour loss or degradation of the fabric. Hence, all the parameters should be precisely controlled to avoid any damage to the garments. In addition, the accessories used should be able to withstand the processing conditions. In some instances the lack of understanding of the material and the process can cause permanent damage to the batch of garments. Hence, a perfect understanding and training of the operators is essential to avoid such problems. In addition, while specifying the care conditions related to ironing/pressing for a care label, the garment should be tested so that it can withstand the specified conditions (Nayak and Padhye, 2014b). 15.6 Future trends We have already seen the trend of increased automation in pressing together with in- creases in the use of computer technology to not only monitor production but also reduce the effect of human error in the pressing operation. It is clear that this trend will continue. Pressing will become more automated, and pressing pressures, temper- atures and the moisture content of steam will be critically controlled using appropriate software integrated into a network. Similarly, automation is applied to other garment- finishing operations. Wet finishing and dyeing processes will continue to be modified as the range of fibres and fibre mixtures increases. Furthermore, consumers are 402 Garment Manufacturing Technology continually demanding increased comfort properties from their garments. These prop- erties will be enhanced by the addition of specific chemical finishes to the garment together with differing fibre mixtures. The concept of nanotechnology is also making its way into garment finishing. New nanotechnology-based concepts such as ease release, quick wick and rare care finishes further improve the functionally of the textile by imparting the various properties such as soil release, anti-pilling effect, water/oil repellency, hygiene effect, easy care and odour-free effect. 15.7 Conclusions Automation and development in technology, in particular the introduction of micro- processors into the garment manufacturing industry, have had a significant effect on production methods. These changes have greatly increased productivity, improving working conditions as well as product quality. 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