000001
`
`BEDGEAR 1021
`IPR of U.S. Pat. No. 9,109,309
`
`

`
`
`
`KNITTING CORE-SPUN YARNS
`Yarns for knitting, spun with a core of
`Chemstrand Blue “C” spandex, can be used
`either on an “as-is” basis, or plied with
`100 per cent textile fiber yarns such as those
`spun from Acrilan acrylic fiber, wool, etc.
`The reasons core-spun and regular textile
`yarns are sometimes plied are as follows:
`‘ To reduce stretch to a level more prac-
`ticable for
`the specific fabric being
`knit.
`
`To accomplish this in the most effective
`manner, the tension should be applied to the
`core-spun yarn on the side of the cone rather
`than by passing the yarn through a disc or
`disc compensator tension device. Just two
`of the several cone-side tensioning devices
`suitable for core-spun yarns are the Mellor
`Bromley Neversnarl* (British Patent No.
`548,667) shown in Figure 24, and the Yarn
`Monitor? (U.S. Patent No. 3,099,418) made
`by Stop-Motion Devices Corporation shown
`in Figure 25.
`
`KNITTING
`
`Yarns spun with a core of Blue “C” span-
`dex or core-spun yarns plied with textile
`yarns can be knit on multi-feed circular
`knitting machines either: 1) from all feeders,
`or 2) in conjunction with companion textile
`yarns from alternate feeders, 1 feeder in 3,
`1 in 4, 1 in 6 or in any other ratio.
`
`\ To add texture. In this respect a wide
`variety of new and different textured
`effects in the fabric can be obtained
`by, for example: plying a cotton sys-
`tem core-spun yarn with a Worsted
`spun textile fiber yarn; or plying a
`core-spun yarn in a light count with a
`textile fiber yarn in a heavy count.
`As an alternative to using the core-spun
`yarn “as-is” or plying with another yarn, the
`core-spun yarn can be knit in conjunction
`with companion textile yarns from alternate
`feeders. Probably the most dramatic devel-
`opment
`in this area—and one that offers
`tremendous prospects with excellent pos-
`sibilities for dynamic growth—is the manu-
`facture of sweaters made with Blue “C”
`spandex—Turbo processed Acrilan core-
`spun yarns in conjunction with companion
`yarns of 100 per cent Turbo processed
`Acrilan.
`
`Half-hose made with core-spun yarns pre-
`sent another area of great potential growth.
`In this regard, a spokesman for a major
`hosiery manufacturer
`recently predicted
`that the amount of core-spun spandex used
`in hosiery alone may reach 3 million pounds
`by 1970 and that within five years,
`two-
`thirds of all cotton socks will be made with
`core-spun spandex yarns.
`
`TENSION IN KNITTING
`Tension on the core-spun yarn in any
`type of knitting operation should be light-
`just sufficient to straighten out the kinks.
`
`Fig. 24—The Mellor Bromley Neversnarl—
`just one of the several devices used for tension-
`ing yarn spun with a core of Blue “C” spandex
`on the side of the cone.
`
`*Mellor Bromley & Co., (Members of the Bentley Group),
`St. Saviour-’s Road, Leicester, England.
`TStop-Motion Devices Corporation, 155 Ames Court, Plain-
`view, Long Island, New York.
`
`51 000002
`
`000002
`
`

`
`
`
`effect of pulling the wales together to create
`novel effects.
`
`The knitting of core-spun yarns in welt
`stitch structures on jersey sinker top pat-
`tern wheel machines induces stretch char-
`acteristics into what would otherwise be
`
`fairly rigid twill fabrics.
`
`Yarns spun with a core of Blue “C” span-
`dex can also be used most effectively in
`men’s, women’s and children’s half-hose and
`socks either in the stretch tops only, or, for
`maximum stretch,
`throughout
`the hose.
`When knitting core-spun yarn throughout
`the hose, use minimum tensions and knit
`extra-long legs and feet to take care of sub-
`sequent relaxation shrinkage.
`
`When knitting sweater bodies, allowance
`must likewise be made for relaxation shrink-
`age. For
`this reason, bodies should be
`made longer and wider. The total shrinkage
`depends on the amount and denier of the
`Blue “C” spandex core present in a given
`construction, and on whether or not
`the
`core-spun yarn has been heat-set. Machine
`adjustments
`for yield and construction
`should be made by checking steam or
`
`tumble relaxed fabric samples.
`
`Listed below are the yarn counts sug-
`gested for use on various types of knitting
`machines:
`
`Multifeed Yarns
`
`Non-Elastic Yarn
`
`Core—Spun Yarn
`
`Single Jersey
`16 cut
`1/28 to 1/36 w.c.
`18 cut
`1/30 to 1/36 w.c.
`20 cut
`1/32 to 1/36 w.c.
`Double-Knits
`
`1/30 to 1/36 w.c.
`14 cut
`1/32 to 1/36 w.c.
`16 cut
`1/36 to 1/40 w.c.
`18 cut
`Rib Machines
`
`1/32 to 1/40 w.c.
`1/36 to 1/45 w.c.
`1/36 to 1/45 w.c.
`
`1/36 to 1/45 w.c.
`1/36 to 1/45 w.c.
`1/36 to 1/45 w.c.
`
`4 cut
`6 cut
`8 cut
`10 cut
`12 cut
`
`2/8 to 2/16 w.c.
`2/16 to 2/20 w.c.
`2/20 to 2/26 w.c.
`2/26 to 2/32 w.c.
`2/32 to 2/36 w.c.
`
`1/16 to 1/20 w.c.
`1/20 to 1/26 w.c.
`1/20 to 1/26 w.c.
`1/26 to 1/32 w.c.
`1/32 to 1/36 w.c.
`
`Full Fashion
`
`Combination Ply Yarns
`
`21 GG
`
`1/36 to 1/40 w.c.
`
`1/36 to 1/45 w.c.
`
`Fig. 25——The “Yarn Monitor” made by Stop-
`Motion Devices Corporation—another type unit
`that can be used successfully for tensioning yarn
`spun with a core of Blue “C” spandex on the side
`of the cone.
`
`In interlock and double-knit constructions
`
`if desired, be knit
`the core-spun yarn can,
`on dial needles only. This technique facili-
`tates the production of brushed surface in-
`terlock constructions because it permits the
`core-spun yarn to be knitted on the inside
`of the fabric and the textile yarn on the
`outside which, in finishing, can be brushed
`
`up for effect and hand.
`In jersey inlay or jersey fleece fabrics, the
`core-spun yarn can be either: 1) knit at
`every feed—in which case a fabric with a
`highly elastic backing results, or 2)
`if less
`stretch is desired, knit at alternate feeds in
`
`conjunction with textile fiber yarns.
`
`Variety in both rib and jersey construc-
`tions is made possible by feeding in the core-
`spun yarn so that the other parts of the
`structure are raised to give a bouclé or
`puckered effect. The technique consists of
`floating the core-spun yarn across more
`than one wale, an action which, because of
`the elastic properties of the yarn, has the
`
`62
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`000003
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`

`
`
`
`ELASTICIZED FABRICS FOR SWIMWEAR
`
`The amount of natural elasticity in inter-
`lock and other type fabrics for swimwear is
`comparatively small and must, therefore, be
`supplemented by either: 1) knitting the
`fabric from yarns possessing high stretch
`characteristics such as stretch nylon, and/or
`2)
`incorporating spandex into the fabric
`structure during knitting. In this latter con-
`nection,
`the excellent stretch and return
`characteristics, high strength, exceptional
`flex life, and resistance to oils and sun-tan
`lotions of Chemstrand Blue “C” spandex
`are being exploited to the full in the intro-
`
`duction of new concepts to the swimwear
`market. The light-weight, form-fitting gar-
`ments with excellent figure control being
`made from fabrics powered with the yarn
`have proved a boon to the trade and a de-
`light to the consumer. Their comfort and
`ease of care in washing and drying add to
`consumer appeal.
`In most cases, less than
`10 per cent of Blue “C” spandex is sufficient
`to produce fabrics with stretch recovery and
`general performance comparable, if not su-
`perior,
`to conventional
`fabrics produced
`using textured or rubber yarns.
`
`KNITTING BARE CHEMSTRAND BLUE ”C" SPANDEX
`
`In knitting elasticized fabrics for swim-
`wear, the Blue “C” spandex component can
`be used either covered or bare. Of the two,
`however, knitting the Blue “C” spandex
`bare is generally the most efficient and eco-
`nomical way to combine, in any knit con-
`struction,
`the unique properties of
`fine
`denier with high strength and recovery
`force, good resistance to abrasion, long flex
`life, dyeability and resistance to oils and lo-
`tions. Properly designed and balanced fab-
`rics in single jersey, interlock, and jacquard
`constructions
`(discussed in detail
`later)
`powered with bare Blue “C” spandex, offer
`superior performance and economic advan-
`
`tages over conventional stretch fabrics. Ad-
`ditionally they can be made aesthetically
`more attractive because of the versatility of
`effects possible in constructions ranging
`from the feather weight and sheer, to form-
`fitting foundation-type garments.
`In most
`constructions it is advisable to keep the
`bare Blue “C” spandex component on the
`back of the fabric or buried in the construc-
`tion. The simplest and most commonly rec-
`ommended methods of accomplishing this
`include:
`
`1. Either plating the Blue “C” spandex
`component
`(suggested primarily for
`single jersey constructions) or
`2. Modifying standard or interlock con-
`structions so that the Blue “C” span-
`dex is introduced to the back or dial
`
`position only, at pre-determined in-
`tervals.
`
`Laying-in of the spandex by the conven-
`tional tuck-miss selection of needles is sel-
`dom satisfactory as a method of incorpo-
`rating bare Blue “C” spandex into the
`knitted structure of elasticized swimwear
`fabrics, and should usually be avoided.
`
`Here are several suggestions that will as-
`sist materially in the knitting of elasticized
`swimwear fa b r i c s powered with bare
`Blue “C” spandex:
`
`‘ Metering Y3I'n- Success in using bare
`Blue “C” spandex in elasticized swim-
`wear fabrics is contingent upon pre-
`cise metering of
`the yarn to the
`needles. Three devices that report-
`edly perform this function well are:
`1)
`the Scott and
`Elastic
`
`*Scott and Williams, Inc., Laconia, N.H.
`
`o(§8oo4
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`000004
`
`

`
`
`
`the knitting is done on a jersey, plain rib,
`
`interlock or double knit basis. Probably the
`
`major advantage of knitting-in over laying-
`
`in is that the resultant structure possesses
`
`two-way stretch. Spandex yarns that are
`
`laid-in on a jersey, plain rib, interlock or
`
`double knit ground impart only one-way
`stretch to the resultant fabric.
`
`Wrapping has much to recommend it as a
`
`procedure for incorporating spandex in a
`
`swimwear
`
`fabric. Spandex is
`
`introduced
`
`weft-wise on a jersey basis, and wrapping
`
`yarns are introduced in a warp-wise direc-
`
`tion.
`
`If the wrapping yarn is a moderately
`
`elastic one such as textured nylon, a resilient
`
`fabric will
`
`result possessing lengthwise
`
`stretch.
`
`If in addition, the highly elastic
`
`spandex is fed on a knit-in basis in a Weft-
`
`wise direction, a two-way stretch fabric will
`
`be produced. Spandex yarns also may be
`
`wrapped at predetermined feeds to produce
`
`panels of stretch, for example, in the sides
`of swimsuits to assure a form-fit.
`
`Plating
`
`(recommended primarily
`
`for
`
`single jersey constructions) is the technique
`
`in knitting involving the simultaneous feed-
`
`ing of two yarns, one to appear on the face
`of the fabric and the other on the reverse.
`
`In plating, the Blue “C” spandex component
`
`is fed almost simultaneously with a textile
`
`or non-elastic yarn so that the former ap-
`
`pears on the reverse side of the fabric.
`
`The best and most generally used means
`for incorporating Blue “C” spandex in spe-
`cific type knit fabric structures——single jer-
`
`sey, interlock, jacquard, blister, and ripple—-
`
`are shown in Figure 47 and discussed below.
`
`SINGLE JERSEY FABRICS
`
`For
`
`single
`
`jersey
`
`construction,
`
`the
`
`Chemstrand Blue “C” spandex component
`
`can be introduced into the fabric by either:
`
`1. Plating.
`
`2. Laying-In. Extra lateral stretch can
`be developed in single jersey fabrics
`by laying-in the Blue “C” spandex
`component which,
`for best results,
`must be covered. Laying-in is best
`accomplished by introducing the cov-
`ered Blue “C” spandex in alternate
`feeds, tying-in in odd wales at Feeds
`2, 6, 10, etc., and in even wales at
`Feeds 4, 8, 12, etc. The repeat cycle
`of movements extends over
`four
`
`feeds. After a row of cleared loops
`
`has been made from textile yarn
`
`at the first feed, the Blue “C” span-
`dex component
`is supplied to odd
`needles at the second feed, and after
`
`another row of cleared loops has been
`made from textile yarn at the third
`
`feed, the Blue “C” spandex is sup-
`plied to even needles at the fourth
`feed. Needles are raised to tucking
`
`height to receive the Blue “C” span-
`
`dex component.
`
`3,
`
`Introducing the Spandex at Every
`
`Third Course. A plain jersey fabric
`can be adapted for swimwear by hav-
`ing every third course knit using
`Blue “C” spandex,
`the yarn being
`fed under very light tension so that
`
`the loops formed from it are not too
`tight. The introduction of Blue “C”
`spandex in this way produces two-
`way or dual stretch.
`
`INTERLOCK FABRICS
`
`Almost all double knit machines of the
`
`modern interlock type can be
`
`readily
`
`adapted to make elasticized fabric for swim-
`wear.
`Interlock fabric made from textured
`
`nylon yarn elasticized with Chemstrand
`Blue “C” spandex lends itself admirably to
`screen printing for the production of figure
`designs in color, and in this respect serves as
`a convenient substitute for the more expen-
`
`In unpatterned in-
`sive jacquard designs.
`terlock fabric, the introduction of Blue “C”
`
`94
`
`000005
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`
`

`
`
`
`FIG. 47—ME'I'HODS OF INCORPORATING BLUE "C” SPANDEX IN KNITTED SWIMWEAR FABRICS
`
`
`
`
`
`
`
`
`
`
`
`
`Spandex laid in on reve
`The spandex i
`'
`trodu
`words, alterna
`ucks and
`
`side of jer
`a tuc
`ats.
`
`(single cylinder) fabric.
`nd knit basis;
`in other
`
`rib fab '
`Spandex laid in on a plain 1 x l
`is introduced in the form of straight wet
`rib and plain wales.
`
`. The spandex here
`reads between the
`
`Spandex knitted in on every third course of conventional
`bric.
`(single cylinder)
`fa
`
`jersey
`
`Spandex knitted in on a
`course intervals.
`
`1
`
`x
`
`1
`
`rib fabric at predetermined
`
`
`
`
`E
`Spandex incorporated in interlock-type double knit fabric. The
`body yarn is supplied to long cylinder and long dial needles at
`feeds 1 and 5, and to short cylinder and short dial needles at
`feeds 2 and 6. The spandex is supplied to long dial needles at
`feed 3 and to short dial needles at feed 4.
`
`F.
`Spandex knitted into rib jacquard fabric. The white and gray
`loops
`esent
`the body jacquard yarns and the black lo
`the sp
`ex. The latter is
`introduced to odd needles at
`third feed and even needles at
`the sixth feed. Structure is
`based on six feed repeat cycle in dial knitting.
`
`95
`
`000006
`
`
`
`
`I Amgnm
`
`
`
`
`"
`
`
`
`‘
`
`
`
`‘I.
`Um‘
`‘no
`I’
`
`
`
`
`000006
`
`

`
`
`
`SCOURING, BLEACHING, DYEING AND FINISHING
`
`The development of procedures for scour-
`ing, bleaching, dyeing and finishing fabrics
`powered with Chemstrand Blue “C” span-
`dex is advancing at a very rapid pace, and
`many innovations continue to be made—
`
`In the
`even as this bulletin goes to press.
`subsequent discussions, therefore, we have
`presented merely an outline of the methods
`of handling these fabrics. The recommenda-
`tions given, nevertheless, will be of invalu-
`able assistance in helping mills establish
`commercial procedures on their own equip-
`ment. For more complete information in
`regard to the dyeing and finishing of fabrics
`elasticized with Blue “C” spandex, contact:
`Applications Research and Service Depart-
`ment, Chernstrand Company, Decatur, Ala-
`bama. The Dyeing and Finishing Service
`Facility of this Department matches shades
`submitted by the customer, works out com-
`plete details of formula, application condi-
`tions and performance, and sends a report
`to the customer, usually in the form of a
`specially prepared booklet. VVhen required,
`Chemstrand’s Dyeing and Finishing Service
`specialists carry out service calls and there-
`by make their highly specialized knowledge
`and skills directly available to the customer.
`
`BASIC PRINCIPLES
`
`Conditions used in the dyeing and finish-
`ing of fabrics powered with Blue “C” span-
`dex must be such as to conserve the highly
`elastic nature of the spandex component.
`With this foremost in mind, the basic prin-
`ciples of dyeing and finishing fabrics elas-
`ticized with Blue “C” spandex, as now
`known, include the following:
`
`1. Where maximum stretch in a fabric
`
`is desired* or when the stretch must
`
`be conserved,T it is essential at every
`*As in most power net fabrics and most woven
`foundation garment fabrics.
`tAs in some warp and filling stretch woven fabrics
`elasticized with heat—set Blue “C" spandex core-
`spun yarns.
`
`159
`000007
`
`step in dyeing and finishing that: a)
`tension on the fabric be kept as low
`as possible, especially in those opera-
`tions carried out at elevated tempera-
`tures, b)
`that
`temperatures used
`should be as low as possible consist-
`ent with the necessity for good pene-
`tration of dyes and fixing agents, and
`effective heat setting (where heat
`setting is required), and c) that the
`duration of treatment be as short as
`
`possible consistent with the attain-
`
`ment of good results. High tempera-
`tures and excessive tensions do not
`
`degrade Blue “C” spandex easily, but
`they do induce loss of final elasticity
`because of non-elastic stretching and
`a permanent set
`in the stretched
`
`form. Unfortunately, once the elas-
`tic properties of Blue “C” spandex
`have been diminished due to the use
`
`of excessive tension, temperature and
`time, they cannot be restored satis-
`factorily. We recognize that it is easy
`to say “use minimum times, tempera-
`tures and tensions where maximum
`
`stretch in a fabric is desired” but that
`
`this is not practical for many fabrics.
`The message we are trying to convey
`to the dyer or finisher is to use discre-
`
`tion in making decisions in regard to
`the processing of
`these fabrics.
`If
`the dyeing temperature for a certain
`fabric is somewhat high, then’ try to
`reduce tension and time to the mini-
`
`mum. Likewise, if a fabric must be
`
`processed under tension, reduce the
`temperature and time factors to the
`minimum.
`
`. High concentrations of chemicals and
`
`extremes of pH, particularly at ele-
`vated temperatures, should be avoid-
`ed since these may damage the span-
`dex. Fabrics powered or elasticized
`
`000007
`
`

`
`‘.1
`
`
`
`with Blue “C” spandex core-spun
`yarns can be carbonized but should
`
`be neutralized immediately after
`baking. Likewise,
`fabrics
`contain-
`
`ing Blue “C” spandex can be mer-
`
`cerized—but cold (60°F). An area
`where much care must be taken
`
`is in the stripping of core—spun fabrics.
`Strong oxidizing agents containing
`chlorine must be avoided since they
`seriously impair the strength of the
`spandex. For stripping,
`in general,
`reducing agents are employed since
`they are milder and do not appre-
`ciably affect
`the properties of
`the
`spandex.
`
`. All fabric should be processed on a
`first-in-first-out basis.
`
`4. To prevent “snagging” on minor nicks
`or rough spots it is most important
`that all equipment used in dyeing
`and finishing elastic fabrics be per-
`fectly smooth and clean.
`
`.
`
`In many cases, but particularly in
`filling stretch fabrics,
`tacking the
`fabric “face-in” before dyeing will
`help prevent rolling of selvages and
`minimize the formation of creases and
`
`crack marks.
`
`. Both greige and finished fabrics
`
`should be wrapped during storage.
`
`. To avoid complaints, the fabric, when
`shipped to the cutter, should ideally
`have a residual shrinkage potential of
`from 1 to 2 per cent. Growth poten-
`tial rather than a small amount of
`
`in a
`shrinkage potential
`residual
`fabric is extremely undesirable and
`all precautions should be taken to
`
`insure against same.
`
`. Effective quality control programs
`should be established from the time
`
`that the goods enter to the time that
`
`they leave the dyeing and finishing
`plant.
`
`TECHNIQUE
`
`As might be expected, different types of
`elastic fabrics powered with Blue “C”
`spandex require totally different dyeing and
`finishing techniques, and in different dye-
`houses techniques must be further varied to
`
`installed equipment. Typical dyeing
`suit
`and finishing routines for various type fab-
`rics elasticized with Blue “C” spandex are
`outlined in Table 19.
`
`EQUIPMENT
`
`Scouring, Bleaching and Dyeing Equipmeni
`
`For Foundation Garment Fabrics—For
`
`best results, most open-width power net
`and warp stretch woven foundation fabrics
`
`powered with Blue “C” spandex should be
`
`scoured, bleached and dyed in tensionless
`jigs such as the Vald. Henriksen machine
`shown in Figure 83. In contrast,
`filling
`stretch fabrics, which do not require the
`same degree of warp tension control may
`be processed in jigs that do not have spe-
`cial
`tension controls providing that
`the
`spreader bar is adjusted or modified to
`
`minimize filling tensions. In some instances
`
`an open jig can be used satisfactorily for
`dyeing fabrics powered with Blue “C” span-
`dex to light shades—b1ue, pink, salmon and
`yellow, but a closed jig is almost always pre-
`ferred. The reasons: 1) with a closed jig,
`processing conditions are more uniform, and
`2) elevated temperatures, which not only
`enable dyeing to proceed more rapidly but
`additionally are essential for the successful
`
`dyeing of many of the companion yarns
`used in conjunction with the Blue “C” span-
`dex, are more easily achieved and main-
`tained in a closed jig.
`For Woven Fabrics Made with Core-Spun
`Yarns—Fabrics in this category of the fill-
`ing stretch variety can, after being heat-set
`in the greige, be scoured, bleached and dyed
`satisfactorily in open or closed dye becks. .
`For Circular Knit Fabrics—Circular knit
`
`fabrics may be scoured, bleached and dyed
`
`160
`000008
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`

`
`.{§.’, '
`
`Courtesy: Vald. He‘iksen i/S.
`
`Fig. 83—The Vald. Henriksen Universal Precision Jig Type VH-Super.
`
`satisfactorily in dye becks. Shallow becks
`equipped with reels close to the dye liquor
`are preferred to reduce the tension created
`by pulling wet fabric from the hot bath.
`
`For certain specialty type fabrics which
`require complete relaxation during dyeing
`(lace elasticized with Blue “C” spandex, for
`example), paddle dyeing machines must be
`used.
`
`The drying of open width fabrics powered
`with Blue “C” spandex should be carried
`out, wherever possible, using an overfeed
`tenter frame such as the ones shown in Fig-
`
`ures 84 and 85. Circular knit fabrics pow-
`
`ered with Blue “C” spandex are usually loop
`dried or processed on one of the several dif-
`
`ferent types of tubular drying equipment
`available.
`
`Other items of equipment that may be
`
`required in the finishing of elastic fabrics
`powered with Blu_e “C” spandex include
`machinery for: pad application of resins;
`
`pahnering; decating; calendering;
`
`rotary
`
`pressing; shearing, napping and sueding.
`
`To prevent cockling, puckering, and dis-
`tortion of the fabric due to non-uniform
`
`processing tensions during weaving or knit-
`ting, foundation garment fabrics should be
`
`relaxed before wet processing.
`
`Specifically, the objects of the relaxation
`
`steps are:
`
`1. To release latent tensions that orig-
`
`inated during knitting or weaving.
`
`2. To induce fabric shrinkage.
`
`163
`
`000009
`
`000009
`
`

`
`3. To obtain better finished fabric di-
`
`mensional stability.
`
`Open width fabrics such as filling and
`warp stretch lenos and power nets can be
`relaxed by either: 1) a hot water treatment,
`or 2) by passing over a steam box. Of the
`two, however, the steam box method is pre-
`ferred. The reason:
`the fabric is processed
`in a more relaxed state, whereas with a hot
`water treatment full relaxation of fabrics
`
`with a high shrinkage potential is seldom
`
`realized. In most cases, the steam box con—
`
`sists of a trough through which several
`steam pipes (perforated for steam ejection)
`run. For best results, the steam box should
`be fitted with a top hood to prevent the
`moisture of condensation from dripping onto
`the fabric.
`
`A positive overfeed device should be used
`
`to permit fabrics to pass over the steam box
`fully relaxed. The duration of the relaxation
`
`period will depend on fabric construction,
`rate of steam generation, and speed of cloth
`
`P
`
`over the steamer. The use of a scray pan for
`
`collecting fabric from steaming equipment
`is beneficial because it permits additional
`
`lengthwise shrinkage and provides better
`over-all dimensional stability.
`
`Filling Stretch Woven Fabrics Made Witl1
`Core-Spun Yarn
`
`Most filling stretch woven fabrics made
`
`with Blue “C” spandex core-spun yarns
`
`l
`l
`
`‘
`
`‘W
`
`‘ll
`
`must be heat-set* in the greige. The reason:
`\
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`Fig. 84—Krantz finishing range consisting of vacuum extractor, two-bowl padder and multi-tier jet
`tenter.
`
`164
`
`000010
`
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`
`

`
` {Cloth travels directly from this
`
`Windup end of pin frame tenter with
`overfeed mechanism)
`
`
`
`4 Pin frame tenter, overfeed mechanism and con-
`trol panel. Chain drive for the unit was designed
`to go under the concrete floor, out of sight, yet
`readily available for service. Average running
`speed is reportedly 25 yds/min.; aVeF3g€ drying
`temperature: 375°F.
`
`Courtesy: Fablok Mills, Inc.
`Fig. 85——This drying unit, made by Morrison Machine Company, Paterson, N. J., is reportedly
`being used with great success for the drying of foundation garment fabrics powered with spandex.
`Features of the unit are these:
`
`It utilizes a heavy duty, standard type tentering
`1)
`frame. and incorporates engineering and manufacturing fea-
`tures designed to assure uninterrupted performance with a
`minimum of maintenance.
`
`2) It is capable of a wide range of speeds and is engi-
`neered so that all changes, whether in speed, overfeed or
`width. can be controlled from a centrally located control
`panel.
`
`3) An overfeed mechanism allows the operator either
`to overfeed the fabric in a relaxed state or to stretch the
`fabric as desired. The unit
`is mechanically capable of
`over or underfeeding the fabric from 40 per cent plus
`to 15 per cent minus. It is also equipped with entering end
`scroll rolls and motor driven finger selvedge openers.
`4) Heat
`transfer, described as efficient and uniform,
`
`is accomplished by using specially designed gas-fired
`burners with high air velocities. Each drying chamber is
`equipped with independently adjustable dampers for regu-
`lating the circulating volume of air. The drying portion
`of the unit is designed to accomplish in a 40 ft. housing
`unit.
`the drying effect
`that would normally require a longer
`
`The heating chamber temperature can be raised from
`100° to 200°F in about ten minutes.
`5) The unit has a low profile housing with small heat-
`ing area and rapid recirculation of air to give accurate
`temperature controls and efficient, economical operation.
`6) The unit is equipped with a water-cooled drum over
`which fabric can be run before windup. This is especially
`valuable with delicate elastic fabrics.
`
`165
`
`00001 1
`
`
`
`000011
`
`

`
`the actual stretch potential of these fabrics
`
`4. Rinse in cold water.
`
`is often 100 per cent or more—in other
`
`words, far in excess of 25 to 65 per cent
`
`stretch generally required by most cutters.
`
`For this reason, the width of the fabric must
`
`to give the desired
`be adjusted and set
`stretch in the finished fabric. This is best
`
`5. Extract sample in a centrifugal ex-
`tractor.
`
`6. Flat dry at 160° to 180°F for 10 min-
`utes.
`
`7. Mark the relaxed fabric with 10-inch
`
`bench marks in the stretch direction.
`
`accomplished by heat setting in the greige.
`
`8. Stretch the sample by hand to its
`
`In addition to fulfilling its primary ob-
`
`jective,
`
`i.e., that of reducing stretch, there
`
`is an added advantage of heat setting in
`
`maximum elongation and record the
`
`distance between the original 10-inch
`
`marks.
`
`(This technique for measur-
`
`the greige:
`
`it greatly improves the appear-
`
`ing stretch is sometimes designated
`
`ance and hand of the finished fabrics. Quite
`
`the “New York Hand Stretch Test.”)
`
`9. Maximum stretch potential is then
`calculated using the following for-
`mula:
`
`B — A
`
`‘< HO0
`
`_I
`
`Maximum per cent
`stretch potential
`
`Where:
`
`A : Original relaxed length
`R = Extended length
`
`NOTE: Once the maximum stretch potential has been
`determined. it can readily be ascertained whether the de-
`sired stretch and desired width in the fabric are feasible.
`If. for example,
`the boiled-off sample shrinks from 66 to
`36 inches and contains 100 per cent stretch and the desired
`finished stretch is ‘100 per cent at 45 inches. then clearly
`nothing can be done in finishing to achieve the desired
`end result.
`
`Step 2—As the second step in determin-
`
`ing the width at which to heat-set in the
`
`greige to obtain the desired stretch, apply
`
`the following formula:
`
`Width at which fabric
`must finish to give
`desired stretch
`
`:
`
`A (100 +B)
`100+C
`
`Where:
`
`A : Boiled off width of 1 yd. sample
`B = Maximum per cent stretch potential
`C : Desired per cent stretch in finished fabric
`NOTE: The above formula is not
`infallible because of
`fabric construction and other variables.
`It nevertheless
`helps eliminate a great deal of experimentation and re-
`processing and has proven of great value to dyers and
`finishers processing stretch fabrics elasticized with core-
`spun yarns.
`
`Step 3—To the width at which fabric
`must finish to give desired stretch obtained
`in Step 2, add several inches (generally from
`2 to 3)
`to take care of
`the from 5 to
`
`20 per
`
`cent
`
`relaxation shrinkage
`
`that
`
`will occur in the fabric after heat setting in
`the greige. This will then give the approxi-
`mate width at which the fabric must be
`
`often fabrics that show a very high shrink-
`
`age or stretch in a boil-off sample will turn
`
`out cracked and puckered when they are
`
`boiled-off in the full piece. This condition
`
`is very hard to correct, and the appearance
`
`of the finished pieces of such a fabric can-
`not compare in smoothness with that of
`
`heat-set pieces. Heat setting in the greige
`also conserves the strength of the filling
`yarns in filling stretch fabrics, the reason
`
`being that it puts considerably less strain
`
`on yarn and fabric to pull it from 46 or 48
`in. to 57 in. than to force it from 36 to 57 in.
`
`Determining Width At Which To
`Heat-Set In The Greige
`
`Step 1—The first step in determining the
`
`width at which to heat-set filling stretch
`
`fabrics in the greige is to determine the
`
`maximum stretch potential of the greige
`goods.
`
`A simple, inexpensive and effective meth-
`
`od for doing this is as follows:
`
`1. Cut a one-yard head end of greige
`
`fabric and protect edges from ravel-
`
`ing.
`
`2. Prepare a bath with 0.5 to 1.0 per
`cent o.w.f. of a non-ionic detergent
`and a small amount of TSPP (tetra-
`
`sodium pyrophosphate).
`
`3. Raise the temperature from 100° to
`
`208°F and wash sample at 208°F for
`10 minutes.
`
`166
`
`000012
`
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`
`

`
`
`
`heat-set to obtain the desired stretch. Heat-
`set a one yard end at this width using a suit-
`able heat setting temperature and duration
`of treatment (see discussion on heat setting
`technique below). Then boil-off the heat-
`set sample to determine the relaxation
`shrinkage. Having obtained this, one can
`then make suitable allowances and specify
`the exact width at which the fabric should
`be heat-set to obtain the desired per cent
`stretch.
`
`Heat Setting Technique
`
`The greige fabric should be heat-set on a
`frame——preferably equipped with a steamer
`at the entering end to start shrinkage and
`make it easier for the pins to grip the fabric.
`Heat-setting conditions across the fabric
`from selvage to selvage must be consistent
`to prevent the possibility of side-to-center
`shading caused by uneven heating.
`Tints and sizes should be checked out
`thoroughly before heat setting to insure that
`they can be completely and easily removed
`after heat treating.
`
`Optimum heat-setting conditions for the
`particular fabric being processed will de-
`pend naturally, on such factors as spandex
`denier, spandex content, yarn count, type
`sheath or hard fiber employed, and fabric
`construction, but in most cases a heat-set-
`ting temperature in the range 360° to 380°F
`for from 20 to 40 seconds will give excellent
`dimensional stability. The effects of vary-
`ing the heat-setting temperature (range
`360° to 400°F) and time (20 to 40 seconds)
`on dimensional stability width, stretch and
`other properties of just one of the many fab-
`rics made with core-spun Blue “C” spandex
`in Chemstrand’s Applications Research and
`Service Department, are outlined in Table
`16 (page 153). In conjunction with the in-
`formation presented in Tables 17 and 18
`these data provide a u