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A Review of Textile Dyeing Proce

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					                          A Review of Textile Dyeing Processes
By W A R R E N S. PERKINS, Department of Textile Engineering, Auburn University, A u b u r n , Ala.'


                                                                                                       dye beck consists of a reservoir or trough
T
                                                            1-A-
      extile materials can be dyed using
       batch, continuous or scmi-continu-                                                   - Reel     which contains the dyebath and a reel to
ous processes. The type of process used                                                                move the loop of fabric through the dye
dependson seberal things including type of                                                             formulation. The liquor to goods ratio
material (fiber, yarn, fabric, fabric con-                                     idler roll              used in becks is typically 15:l or higher
struction, garment), generic type of fiber,          Door                                     Fabric   although becks using ratios as low as 4:l
sizeofdye lots and quality requirements in                                                             are available.




                                                                        J
                                                                        ' A
thedyed fabric.                                    Peifornted
                                                                              QyobAth
                                                                                                          The dye beck is sometimes called a
                                                    Divider     ---                                    winch because of the winch mechanism
   Machinery for dyeing must be resistant
to attack by acids, bases, other auxilary                                                              used to move the fabric. The ends of the
chemicals and dyes. Type 316 stainless            S t e m pipe 7--0                                    fabric piece to bedyed aresewn together to
steel is normally used as the construction                                                             make a continuous loop. The reel pulls the
                                                                      Erein                            fabric out of the dye liquor in the trough
material for all parts of dyeing machines
that will come in contact with dye formu-                                                              and over an idler roll. After leaving the
                                                 Fig. I . Dye beck.
lations.                                                                                               reel, the fabricslidesdown the back wall of
                                                                                                       the beck and gradually works its way from
Batch Dyeing Processes                           substrate. Textile substrates can be dyed             the back toward the front of the machine.
Batch processes are the most common              in batch processes in almost any stage of             Several loops of fabric of about the same
method used to dye textile materials.            their assembly into a textile product in-             length are dyed simultaneously. The indi-
Batch dyeing is sometimes called exhaust         cluding fiber, yarn, fabric or garment.               vidual loops are separated from one an-
dyeing because the dye is gradually trans-       Generally, flexibility in color selection is          other by a dividing device called the peg
ferred from a relatively large volume            better and cost of dyeing is lower the closer         rail extending the width of the machine.
dyebath to the material being dyed over a        dye application is to the end of the manu-            The peg rail contains smooth pegs spaced
relatively long period of time. The dye is       facturing process for a textile product.              several centimeters apart to provide an
said to exhaust -from the dyebath to the            Some batch dyeing machines operate at              opening through which the fabric ropecan
                                                 temperatures only up to 1 OOC. Enclosure              pass. Loops of fabric are typically 50 to
                                                 of the dye machine so that it can be                  100 meters long depending on the weight
                                                 pressurized provides the capability to dye            of the fabric and other factors. The num-
                                                 at temperatures higher than 1OOC. Cot-                ber of loops processed depends on the size
                                                 ton, rayon, nylon, wool and some other                ofa particular machineand mayvary from
ABSTRACT                                         fibers dye well at temperatures of 1OOC or            only one loop in a laboratory or sample
                                                 lower. Polyester and some other synthetic             machine to 50 or more loops in a large
Basic principles of batch and continuous
                                                 fibers dye more easily at temperatures                production machine.
dyeing processes are described in terms
of the equipment used to dye a variety           higher than IOOC.                                        The trough is slanted at its rear to allow
of textile materials. Equipment and                 The three general types of batch dyeing            the fabric layers to slide down into the dye
process are selected depending e n the           machines are those in which the fabric is             liquor and move gradually toward the
substrate type, fiber type, size of dye lot      circulated, those in which the dyebath is             front of the machine. A deep trough and
and quality requirements. Batch (or              circulated while the material being dyed is           steep sloping back works well for fabrics
exhaust) dyeing equipment can be                 stationary, and those in which both the               which do not crease easily while a shal-
subdivided into three groups depending           bath and material are circulated. Fabrics             lower more gradual slope helps to prevent
on whether the substrate, dyebath or             and garments are commonly dyed in ma-                 creasing. The idler roll presses some of the
both are circulated. Batch equipment
                                                 chines in which the fabric is circulated.             excess dye liquor from the fabric, improv-
described includes becks, jets, jigs,
package dyeing machines, beams, skein            The formulation is in turn agitated by                ing exchange of the liquid in the fabric
dyeing machines, paddle machines,                movement of the material being dyed.                  with formulation in the trough.
rotary drum machines and tumblers.                Fiber, yarn and fabric can all be dyed in               Chemicals and dyes used in the dyeing
Continuous dyeing equipment topics               machines which hold the material station-             are added to a compartment at the front of
include continuous dyeing of polyester/          ary and circulate thedyebath. Jet dyeing is           the beck. The divider separating the com-
cellulose blend materials and carpet and          the best example of a machine that circu-            partment from the trough is perforated,
long chain dye ranges for warp dyeing.            lates both the fabric and the dyebath. Jet           allowing the added chemicals to gradually
                                                 dyemachines areexcellent for knit fabrics,             become mixed with the liquor in the
                                                  but woven fabrics can also be dyed using              trough.
KEY TERMS
                                                 jet machines. The following are examples                  Live steam is injected into the compart-
  Batch Dyeing                                   of some batch dyeing machines.                         ment to heat the liquor to the required
  Continuous Dyeing                                                                                     temperature. The injection of steam vigor-
  Dyeing                                          Becks
  Dyeing Machinery                                Atmospheric becks can be used for dyeing             -
  Machinery                                                                                            'The author i h nlro president of AATCC, assuming
                                                  at temperatures up to 1OOC. Pressurized              t h a t pa51 Janudry I following his election last Novem-
  Wet Processing Machinery                        becks are used for dyeing at temperatures            bcr. Hccurrentl! isonil year'srabbatical from Auburn
                                                  higher than 1OOC. As shown in Fig. 1, a              University.


August 1991 CCO                                                                                                                                            23
Dyeing Processes                                   different in these two types of machines.          the fabric is not held in any one configure
                                                   Fig. 2 shows a schematic diagram of a jet          tion very long.
                                                   machine. A high speed jet of dye liquid                  Lengthwise tension on the fabric is
ouslyagitates thecompartment and aids in           created by a venturi transports the fabric         low so the fabricdevelops bulkand fullness
mixing the dyes and chemicals into the dye         through the cloth guide tube of the jet            of handle.
liquor. The steam injected into the beck           machine. A jet machine has a cloth guide                 Dyeing at high temperature of about
condenses in the liquor so some dilution of        tube for each loop of fabric being pro-             130C gives rapid dyeing, improved dye
thedye liquor must be tolerated.                   cessed. A powerful pump circulates the             utilization, improved fastness properties
   The greatest advantages of becks are            liquor through a heat exchanger outside of         and makes possible the elimination of
simplicity, versatility and relatively low         the main vessel and back into the jet              carriers required when dyeing at lower
price. Becks subject fabrics to relatively         machine. The fabric travels at high veloc-         temperatures.
low lengthwise tension and encourage the           ityof 200-800 meters per minute while i t is             The lower liquor ratio used in jet
development of yarn crimp and fabric               in the cloth guide tube. The fabric leaving        dyeing allows shorter dye cycles and saves
bulk. However, becks tend to use large             the cloth guide tube enters a larger capac-        chemicals and energy.
amounts of water, chemicals and energy.            ity cloth chamber and gradually advances              Some disadvantages of jet dyeing ma-
Becks can cause abrasion, creasing and             back toward the cloth guide tube.                  chines compared to becks are as follows:
distortion of some fabrics.                           Pressurizing a jet dyeing machine pro-             0 Capital and maintenance costs are
   A continuous strand can bedyed instead          vides for high temperaturedyeingcapabil-           higher.
of the usual multiple loops of fabric if the       ity. High temperature jet machines are                0 Limited accessibility makes cleaning
beck has this capability. I n this system, a       especially suitable for delicate fabrics           between dyeings and sampling for color
single long strand of fabric is gradually          made of texturized polyester. Some atmo-           during the dye cycle difficult.
spiraled through the dye formulation from          spheric machinesdesigned for dyeing tem-              0 The jet action tends to make formula-
one side of the beck to the other. This            peratures up to lOOC also use the jet              tions foam in partially flooded jet ma-
method decreases the requirements for              circulation principle.                             chines.
material handling, reduces waste and                  Jet dyeing machines provide the follow-            0 The jet action may damage the sur-
eliminates the necessity for trimming and          ing advantages compared to atmospheric             faceof certain types of fabrics.
sewing of individual loops.                        becks for dyeing fabrics made from textur-            Jet dyeing machinery evolved steadily
                                                   ized polyester.                                    after invention of the machine in 1961.
Jet Dyeing                                            0 Vigorous agitation of fabric and dye          The first machines were partially flooded.
Jet dyeing machines resemble becks in              formulation in the cloth tube increases the        Fully flooded machines keep the fabric
that a continuous loop of fabric is circu-         dyeing rate and uniformity.                        completely submerged during the dye
lated through the machine. However, the               0 Rapid circulation of fabric through           cycle. This prevents the formation of
cloth transport mechanism is dramatically          the machine minimizes creasing because             longitudinal creases which occur when the
                                                                                                      fabric is lifted from the bath in a partially
                                                                                                      flooded machine. Fully flooding the ma-
                                                                     Tu b e                           chinealso prevents formation of foam. The
                                                                                                      so-called “soft Row” machines use the
                                                                                                      same principle of a transport tube as a jet
                                                                                                      machine where the fabric is transported in
                                                                                                      a stream of dye liquor. However, transport
                                                                                                      of the fabric in soft flow jet machines is
                                                                                                      assisted by a driven lifter reel. These
                                                                      Chamber                         machines either eliminate the high veloc-
                                                                                                      ity jet or use a jet having lower velocity
                                                                                                      than that used on conventional jet dye
                                                                                                      machines. The soft flow machines are
                                                                                                      more gentle on the fabric than conven-
                                                                                                      tional jet machines. Jet machines offering
                                                                                                  -
                                                                                                  A
                                                                                                  W
                                                                                            9ion T a n k Return L ne


Fig. 2. Jet dyeing machine.
                                                                                Kler

                   Fabric     rolls




                                         Ffibric




Fig. 3 . Dyejig.                                                     Fig. 4. Packagedyeing machine.

24                                                                                                                         CO3 Vol. 23, No. 8
                                                    Peddle
                                                                                                                          Peddle Wheel
                                                                                                                 I   -
                            n




                                                        Ijpbeth

Fig. 5. Side paddle dyeing machine, overhead view                                                 we
                                                                                                   -
                                                                                                                                Per for ate d ple t e
                                                                                                                         Steam Pipes

capabilityofverylow liquor ratiosofabout                                         Fig. 6. Paddle dyeing machine
5 : 1 are also available.
                                                      able for woven than for knit fabrics. Since           the perforations in the spindles and pack-
Jigs                                                  the fabric is handled in open width, a jig is         age cores into the yarn. The flow of liquid
As shown in Fig. 3, a jig consists of a               very suitable for fabrics which crease if             can be either from inside-to-outside of the
trough for the dye or chemical formula-               dyed in rope form.                                    package or outside-in. Periodic reversal of
tion. The fabric from a roll on one side of                                                                 the direction of flow improves uniformity
the machine is run through the formula-               Package Dyeing                                        of dyeing.
tion in the trough and wound on a roll on            The term package dyeing usually refers to                 A package dye machine has an expan-
the opposite side of the jig. When the               dyeing of yarn which has been wound on                 sion tank mounted alongside the dye ves-
second roll is full, the drive is reversed, and      perforated cores so that dye liquor can be             sel. The expansion tank accomodates the
the fabric is transfered through the formu-          forced through the package. Packages                   increased volume of dyebath resulting
lation back to the first roll.                       may be tubes, cheeses or cones. Cores for              from thermal expansion when the bath is
   Live steam injected into the bottom of            dye packages may be rigid stainless steel,             heated. Chemical and dye adds are made
the trough through a perforated pipe                 plastic or paper. Plastic and paper types              to the vessel through the expansion tank.
across the width of the jig heats the                are normally intended to be used only once                A heat exchanger using high pressure
formulation. Closed coils containing high            while stainless steel cores can be reused              steam as the heat source heats the dye
pressure steam can also be used to heat a            indefinitely. Plastic and paper cores as well          liquor in a package dye machine. The
jig. Live steam heats the formulation                as stainless steel springs are used as                 steam coils for heating the liquor are also
faster than closed coils but dilutes the             compressible cores. These compressible                 used as cooling coils after the dye cycle is
formulation. Automatic devices control               cores allow more packages to be forced                 completed.
temperature and reverse the direction of             into the dye vessel and increase the capac-               Liquor ratio in a package dye machine is
the fabric when required on modern jigs.             ityof the machine.                                     typically about 1O:l when the machine is
   A dye jig is normally used for dyeing at             As shown in Fig. 4, the yarn packages               fully loaded. Use of lower liquor ratio can
pressure of one atmosphere although pres-            are placed on perforated spindles on a                 save water, energy and chemicals. The
surized, high temperature jigs have been             frame which fits into a pressure vessel                liquor ratio can be lowered by only par-
made. Covering the top of a jig minimizes            where dyeing takes place. The dye vessel is            tially flooding the machine. If the liquor
heat loss to the atmosphere, keeps the               cylindrical and has domed ends. The top                covers all of the packages but does not fill
temperature uniform on all parts of the              cover, which must be removed for loading               the top dome of the machine, the liquor
fabric and minimizes exposure of the                 and unloading, is secured during dyeing by             ratio is only slightly lower than it is in a
formulation to air. Minimizing exposure              bolts or a sliding ring which can bequickly            fully flooded machine. If only the base of
to air is most important when using sulfur           locked. Most package dyeing machines                   thecarrier is covered withdyesolution, the
and vat dyes since these dyes can be                 are capable of dyeing temperatures up to               liquor ratio may be as low as 4: 1. However,
oxidized by atmospheric oxygen.                      135C. The number of packages may vary                  the direction of liquor flow can only be
   Maximum batch size on a jig may be up             from as few as one in a laboratory machine             inside-out using this arrangement. High
to several thousand meters of fabric. Jigs           to several hundred in a large production               quality dyeings may be more difficult to
exert considerable lengthwise tension on             machine.                                               achieve at very low liquor ratio in package
the fabric and are, therefore, more suit-               Thedye formulation is pumped through                dye machines.
                                                                                                               Raw stock, tow and other materials can
                                                                                                            be dyed using the same principles as
                                                                                                            package dyeing. A basket (cage) is nor-

                                                     -   Corn per tmen t
                                                              Door
                                                                                                  THERMOSOL COOLING
                                                                                                     OVEN    CANS
                                                      Ger ments


                                                      B6th




                                                                           DYE    PRE       DRY   CHEMICAL                     WASH BOXES               DRY
           1,
            -       Steam Pipe        1                                    PAD   DRYER     CANS       PAD                                               CANS

Fig. 7. Rotary drum dyeing machine.                                        Fig. 8. Schematicdiagramofa continuousdyeing range.

August 1991                                                                                                                                               25
Dyeing Processes                                                                                      dye machines are shown in Figs. 5 and 6;-
                                                                                                      Theside paddle machineisshown from the
                                                                                                      top since this gives the best view of the
                                                                                                      location of the parts of the machine. The
mally used to hold these materials during                                                             paddle circulates the bath and garments
thedyeing.                                                                                            around a perforated central island. Chem-
Beam Dyeing                                                                                           icals, water and steam for heat are added
                                                                                                      inside the perforated central island. The
The principles of beam dyeing are essen-                                                              overhead paddle machine is simply a vat
tially identical to those of package dyeing.                                                          w i t h a paddle having blades the full width
Either yarn or fabric can be beam dyed.                                                               of the machine. The blades dip a few
The fabric or yarn is wound on a perfo-                                                               centimcters into thevat tostir the bath and
rated beam. A beam machine can be                    Fig. 9. Example of dye applicator for continu-   push the garments down, keeping them
designed to hold a single beam or multiple           ous carpet dyeing machine.                       submerged in thedye liquor.
beams in a batch. Beam dyeing of warps is                                                                 A rotary drum machine is a cylindrical
practical in producing patterned fabrics                                                              vessel slightly larger than its internal
where the warp yarn will be one color and            knitting. Woolen carpet yarn is sometimes        perforated drum which holds the material
the filling will be another color.                   skein dyed.                                      to be dyed. The perforated drum is divided
                                                        Skein dyeing uses a high liquor ratio and     into several chambers each having its own
Skein Dyeing                                         a lot of energy. Uniform dyeing is difficult     door through which it can be loaded and
In skein dyeing (also called hank dyeing),           to achieve in a skein dyeing machine. Slow       unloaded. The drum rotates horizontally
skeins of yarn are mounted on a carrier              winding and backwinding requirements of          as shown in Fig. 7. Rotary drum machines
which has rods (sticks) at the top and               the process make it labor intensive. Pack-       arecommonly used to dye hosiery.
bottom to hold the skeins. The skeins are            age dyeing has replaced some skein dyeing
suspended in the dye machine and dye                 even though the yarn bulkiness achieved in       Tumblers
liquor is gently circulated around the               skein dyeing is usually not matched in           Tumblers are very similar in principle to
hanging skeins. Perforated plates can be             package dyeing.                                  rotarydrum machines except that they are
used a t the top and bottom of the machine                                                            usually larger. They also resemble large
to help provide uniform flow of the dye              Paddle Machines
                                                     And Rotary Drums                                 commercial drycleaning machines. Tum-
liquor. Alternatively, the dye liquor can be                                                          blers have a perforated drum which ro-
pumped through perforations in the sticks            Paddle machines and rotary drum ma-              tates inside a larger vat which contains the
so that it cascades down over the hanging            chines can be used to dye textiles in many       dye or chemical formulation. The drum
skeins. Skein dyeing produces good bulk in           forms, but these two methods are used            can be divided into compartments to assist
the yarn because of the low tension on the           mostly to dye garments. Steam injection          in agitating the garments, or baffles
yarn in the dyebath. The method is used              directly into the dyebath heats both of          around the periphery of the drum serve to
mainly for bulky yarns like acrylics and             these types of machines. Schematic dia-          tumble the garments in the dye formula-
woolens for knitted outerwear and hand               grams of side paddle and overhead paddle         tion. These machines extract some of the
                                                                                                      water by centrifugal action after comple-
                                                                                                      tion of the dyeing. Tumblers are used for
              STEIAM PIPEa*
                                                 0                                                    dyeing garments and for wet processing          $!




                                                                 1?
                                                                                                      (prewashing) garments dyed with indigo.
                                                                                                      Modern machines of this type are usually
                                                                                                      equipped with automatic controls and
                                                                                                      some are designed to tilt forward to
                                                                                                      provide for easy loading and unloading of
                                                                                                      batchesof garments.
                                                                                                      Continuous dyeing processes
                                                                                                      Continuous dyeing is most suitable for
                                                                                                      woven fabrics. Most continuous dye
                     t
                    CARPET     L                                                                      ranges are designed for dyeing blends of
                                                                                                      polyester and cotton. Nylon carpets are
                                                                                                      sometimes dyed in continuous porcesses
                                                                                                      but the design of the range for continuous
                                                                                                      dyeing of carpet is much different than
Fig. 10. Loop steamer for continuous carpet dyeing machine.                                           that for flat fabrics. Warps can also be
                                                                                                      dyed in continuous processes. Examples of
                           SKYINO                                                                     warp dyeing are slasher dyeing and long
                (OXIDATION BETWEEN INDIQO DIPS)
                                                                                                      chain warp dyeing using indigo.
                                                                                       DRYING         Polyester/Cellulose Blends
                                                                MSHINQ                                A continuous dye range is efficient and
                                                                RlNSlNQ                               economical for dyeing long runs of a
                                                          SOFTENER APPLICATION
                                                                                                      particular shade. Tolerances for color
                                                                                                      variation must be greater for continuous
                                                                                                      dyeing than batch dyeing because of the
                                                                                                      speed of the process and the large number
                         INDIQO DYE BOXES                                                             of process variables that can affect the dye
                                                                                                      application. The process as shown in Fig. 8
Fig. I I . Schematicdiagram of long chain dyeing range.                                               is often designed for dyeing both the

26                                                                                                                         co3 Vol. 23,No. 8
I : .
   0    1
   i         polyester and cotton in a blend fabric in          Thesteamer heats the wet fabric so that        rope and wound as a single strand into a
             one pass through the range. The polyester       the dye can diffuse into the cellulosic           ball (log). The yarn from each ball warp
             fibers are dyed in the first stages of the      fibers. The fabric usually dwells in the         constitutes a continuous rope (chain). A
             range by a pad-dry-thermofix process. The       steamer for 30-60seconds.                         long chain dye range accommodates mul-
             cellulosic fibers are dyed in the latter           The washing section of the range is used       tiple ropes or chains side-by-side so that
             stages of the range using a pad-steam           for rinses, chemical treatments which may         thousandsofyarnsare beingdyed simulta-
             process.                                        be required to complete the dyeing, and           neously. After exiting the long chain dye
                Fabric previously prepared for dyeing        washing of the fabric to remove unfixed           range, each rope is taken u p in a separate
             enters the dye range from rolls. A scray is     dye and auxiliary chemicals used in the          container. After dyeing, each individual
             used to accumulate fabric entering the          dyeing. The dye and chemical formula-            warp is backwound onto a warper beam
             rangeso that the rangecancontinueto r u n       tions used in the padders and washboxes          (section beam) and becomes a supply
             whilea new roll of fabric is sewn to the end    depend on the particular classes of dye          package for the slasher.
             of the strand being run. Uniformity of          being applied.                                       Long chain dye ranges usually have a
             application of dye requires that continu-                                                        wet-out box to wet and partially scour the
             ous dyeing bedone in open width. Typical         Continuous Dyeing of Carpet                     yarn before it enters the dye application
             linespeed in a continuous dyeing process is      A continuous dye range for carpet consists      section of the range. The range contains a
             50 to 150 meters per minute.                    of a dye applicator and steamer. The             series of dye boxes which are designed to
                Padding is a critical step i n continuous     process is designed for application of acid     apply indigo. Indigo has low affinity for
             dyeing. Thedispersedye formulation (and         dyes to nylon. Carpet manufacturers are          cellulose and must be applied in several
             sometimes the dyes for the cellulosic com-       innovativein application ofdye to produce       stages called dips. Each stage consists of
             ponent) is applied in the first padder. The     special color effects on their product. As a     immersing the yarn in a solution of the
             fabric is immersed in the dye formulation       result, many variations of dye applicators       reduced indigo, squeezing to remove ex-
             usually a t room temperature and squeezed       exist. A very high liquor ratio is normally      cess solution, and skying to allow air to
            to give a uniform add-on of dye formula-         required to produce good quality dyeing of       oxidize the dye and make it insoluble. The
            tion across the width and along the length       carpet. As shown in Fig. 9, a typical            shade gets progressively darker a t each
            of the fabric. Low temperature in the            application method is to meter the dye           dip. The dye boxes are large and a circula-
            formulation in the padder minimizes tail-        solution onto the surface of the carpet. The     tion system involving all of the boxes is
            ing. Higher temperature promotes wetting         stream of dye being metered onto the             used to keep the indigo solution mixed well
            of the fabric in the short time the fabric       carpet can be momentarily interrupted to         and prevent tailing of the shade.
            dwells in the pad formulation.                   produce patterned effects. Streams of dif-           Asulfurdyecan beappliedeither before
                The wet fabric leaving the padder enters     ferent color dyes can be applied in dif-         the indigo, giving a sulfur bottom, or after
            a dryer to remove moisture and leave the         ferent patterns to produce special effects.      the indigo to give a sulfur top. The use of a
            dye uniformly deposited on the fabric.              Loop steamers are used in continuous          sulfur dye reduces theamount of the more
            Radiant predrying using infrared energy          carpet dyeing so that the carpet always          expensive indigo needed to produce the
            inhibits migration of the dye. Drying is         faces away from the guide rollers. As            shade and may also modify the fastness
            completed using steam-heated cylinders.          shown in Fig. I O this festooning of the         properties as required for a particular use
               A thermal treatment called thermosol-         fabric prevents compression of the carpet        of the fabric.                           m
            ing fixes the disperse dye on the polyester      pile by rollers in the steamer.
            fibers. The thermosol oven heats the fabric                                                       References
            to a temperature of 390-430C, the exact          Long Chain Dye Range
            temperature depending on the particular          Warp yarnsareoften dyed with indigoand             ( I ) Kulkarni. S. V. et al.. Texrile Dyeing Opera-
            dyes being applied. The dye sublimes and                                                          rions. Noycs Pulbications, Park Ridge. N. J., 1986.
                                                             sulfur dyes using a long chain dye range.
                                                                                                                (2) Wylcs. D . H . , Functional Detign ofColoration
            diffuses into the polyester fibers during the    The process is used where the warp will be       Machinrs in Engirrcering in T a t i l e Colororion. Dyers
            thermosol treatment. The fabric dwells in        one color and the filling another color, as in   Company Publication Trust. Bradford. England.
            the thermosol oven for about one to two          denim fabrics. A schematicdiagram of the         1983.
            minutes.                                                                                            (3) Trotman. E. R., Dyeing and Chemical Tech-
                                                             process is shown in Fig. 11. Ball warps
                                                                                                              nology 01’Textile Fibres, Sixth Edition. John Wilcy
               The cooling cans lower.the fabric tem-        (sometimes called “logs” because of their        and Sons, New York. 1984.
            perature so that it does not heat the            cylindrical shape) are prepared as supply
            solution in thechemical pad. Thechemical         packages for the long chain dye range. A         Author’s Address
            padder applies the dyes (and sometimes           ball warp is a warp in which several             Warren S. P c r k k . 721 Dawn Drive. Auburn. Ala.
            chemicals) for the cellulosic fibers.            hundred warp yarns are condensed into a          36830




                                                                    Problems With Static?
                                                            The Fabric-To-MetalCling Test Apparatus is used in AATCC Test Method
                                                            1 15 to evaluate the electrostatic clinging properties of fabrics. The
                                                            complete test unit is available from AATCC and includes: Metal Test
                                                            Plate, Grounding Plate, Wood Rubbing Block, Urethane Foam Pad.
                                                            Complete set: $ 1 1 1 .OO Order No. 8 3 5 4

                                                                               AATCC
             P.O. Box   12215, Research Triangle Park, NC 27709      Tel: 919/549-8141        Fax: 919/549-8933        VISA OR MASTERCARD ACCEPTED




            August 1991      033                                                                                                                                  27

				
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