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Twill Weave of Fabric

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					               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE

            TWILL WEAVE
                   The twill order of interlacing causes diagonal lines to be
            formed on the cloth as shown in fig. 2.4
            Comparison with plain weave
                • Greater weight
                • Closer setting
                • Better draping quality
            Construction of simple twill- Step-by-Step


            Step – 1 : We used a minimum of three threads (i.e. warp and
                                                                             1
            weft) to construct a twill. We first try the twill                        (1 up 2
                                                                                 2

            down). We make a 3x3 square as:




            Step – 2 : Now we start from the first end and first pick we
            make     our    first   mark     here    (it   represents     the        point   of
            interaction).




            Step-3:
            Now in next pick the point of intersection is moved one
            outward and one upward as




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               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE




            In next pick again the point of intersection is moved one
            outward and one up ward as




            The three steps in construction twill are as follows:




            The twills can be produced from Right to left (also called as
            left hand twill) as shown in fig.




            Or from left to right as ( also called as right hand twills)




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                 PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE




            The Twills can be
                 1.     Warp faced Twill: In which quantity of warp is more on
                        the face of the fabric eg 3/1 twill.
                 2.     Weft faced twill: In which quantity of weft is more on
                        the face of the fabric (e.g 1/3 twill)
                 3.     Warp and faced twill: In which warp and weft are in
                        equal quantity on the face of the fabric (eg. 2/2 twill).


            Twills can be broadly classified into six chief varieties
            1.        Regular or continuous twills
                      In regular       twills    the      diagonal lines   are   formed   by
            advancing the order of interlacing in step of one in either
            directions.
                      In four threads the three orders of interlacing can be
                              1          2       3
            made viz.                                    and 3/1, each can be made to
                                   3         2       1

            incline in either direction, therefore, six different effects can
            be formed.




            These are




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               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE




            Angle of Twill
                     The angle formed in the cloth by a twill weave depends
            upon.
               (a)     The relative ratio of ends and picks per cm.
               (b)     The rate of advancement of interlacing
                     If the EPI and PPI are qual, a regular twill runs at an
            angle of 45º as shown:




                     In fact the angle of the twill with the horizontal can be
            calculated by the formula.




                     Rate of advancement of twill upwards                ends per cm
            Tan α = ––––––––––––––––––––––––––––––––––––× ––––––––––––––
                     Rate of advancement of twill outwards              picks per cm


            Thus if
                     Step upward       = 2
                     Step onward       = 1

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               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE

                     Ends/cm            = 42
                     Picks/cm           = 21
                                       2 412
                     Then tan α =       ×    = 4 α = 76º
                                       1 21
            As in the following twill




            Factors influencing the prominence of twills
                     The relative prominence of twills is chiefly determined by:
                     (a)     The character of weave
                     (b)     The character of yarn
                     (c)     The number of warp and weft threads per inch
                     (d)     The direction of twill in relation to the direction of
                             twist imparted to the yarn.
               (a)         The Character of Weaves -          A twill weaves will be
                           relatively more pronounced if developed from longer
                           than from shorter floats of yarn.
               (b)         Character of yarn – A more pronounced twill will result
                           either from coarse spun of soft spun yarn than from
                           fine spun or hand spun yarns; also from folded yarn
                           than from single yarn.
               (c)         Number of Threads per inch – A twill will be relatively
                           more or less pronounced in proportion to the number
                           of warp threads and picks of weft per inch.


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                 PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE

                 (d)     Direction of twill with relation to the direction of twill
                         in the yarn
                       If twills are produced in the reverse direction to that of
            the twist in the yarns, they will be more pronounced and if
            twills are produced in the same direction as that of the twist
            in the yarn, they will be less pronounced.
            2.         Zig Zag or Wavy twills
                       Wavy twills are those in which the direction of twill is
            frequently reversed. Wavy twills are normally made on point
            drafts. The following is an example of wavy twill:




            3.         Herring Bone Twills
                       Unlike wavy twills, the herring bone twill does not come
            to a point where it changes the direction, but instead one twill
            line in said to cut into the other at the pint of reversal.


            Construction of Herring Bone twills
                       We will construct a simple Herring Bone twill. We
            construct it on eight ends.

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               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE

            Step-1 :
            Construct a simple, 1/3 twill on 4 ends




                   Step-2: Now working of 5 th end will be exactly opposite to
            that of 4 th end i.e. where crosses are replaced by blanks in 5 th
            end and blanks by crosses i.e.




                   Step-3 : Similarly working of 6 th end is opposite to that
            of 3 rd ; 7 th, opposite to that of 2 nd and so on; so that the final
            herringbone twill will look like:




            Broken twills


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                 PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE

                   A large variety of effects can be produced by breaking a
            regular twill.
                   There are two ways of obtaining broken twills.
                   1.    Break and reversal methods.
                   2.    Entering and skipping method
            1.     Break and Reveal method
                   In this we first decide the break unit i.e after how many
            threads the twill will be broken. Generally ‘it’ is half the
            number of threads in the repeat of a regular twill.
            Same examples
            1.     2/2 twill (break point : half the number of threads)
                   The regular twill is indicated as




                   In this case we run the twill in regular direction till half
            the threads, however the ends in the second half of repeat are
            run in reverse order:
                                        Draft




                                        Design

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               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE



                   3.    4 up 4 down twill (Break point 2 threads) the
                         original twill in indicated as




                   There we run the twill for 2 threads, then for next 2
            threads reverse it, again we run as regular twill for 2 threads
            and again we reverse it as shown:




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                 PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE




            2.     Entering and skipping method
                   This method is applicable to twills that are composed of
            equal warp and weft floats. In this, threads in the ordinary
            twill are entered and skipped. Generally the number of threads
            to skip is one less than half the number of threads in the
            repeat of the twill.
            Example: in a
                                                                        6   
            2-and-2 twill the no of threads to skip will be 2  −1
                                                              2 
                                                                        8   
            3-and-3 twill the no of threads to skip will be 3  −1
                                                              2 
            4-and-4 twill the no of threads to skip will be 3 (8/2-1)
            Some examples
            2-and-2 twill
            Step – 1:
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               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE

             Calculate the number of treads that will be taken of regular
            twill in order to enter and skip.
            For n-and-n twill it will be (n+n) x 3
            Thus for 2-and-2 twill no of threads = (2+2) x 3 = 12
            Thus for 3-and-3 twill, no of threads = (3+3) x 3 = 18
             Step 2 :
            Make repeats of the no of threads calculated as above with the




            twill given. Thus we make 2-and-2 twill on 12 threads as:


            Step 3: Now we prepare another design from this by taking 2
            ends and then skipping one alternately. Thus is every 3 ends 1
            end will be skipped, in 12 ends 4 ends will be skipped so
            design will be of 8 ends.




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               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE




            TRANSPOSED OR RE-ARRANGED TWILLS
                         By means of transposition or rearrangement of the
            original order of the threads in a regular twill, many new and
            attractive designs can be created.
            Transposition can be done in many ways
              Let’s take a 12 thread twill as




            Transposition this twill line in group of 2 we have.




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               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE




            Similarly we can transpose this twill line in group of 3 as




            Similarly we can transpose it in the groups of 4.
            In the above cases we have rearranged all the threads. These
            were the examples of full transposed twill. We can also have
            a half transposed twill. In which only half of the ends are
            rearranged. Below is the example of a half transposed twill in




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               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE

            which o represent the half transposed base and X represent
            the weave. It is an example of 4/4 half transposed twill:


            One more example of transposed or rearranged twill is satin.
            Combined twills
                         Combined twills are those produced by arranging
            the treads of two continuous twill weaves alternately with each
            others. It can be learnt with the help of an example.
            Suppose we want to combine two 4-and 3-end twill as




            represented by A and B.


            One twill say A- is first indicated on the odd vertical spaces.
            Then to complete the design, twill B is indicated on the even




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               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE

            vertical spaces as shown by the design.
            Each twill must be carried out on 12 ends and picks – the
            l.c.m of 4 and 3, hence the design consists of 12 threads of A,
            combined with 12 threads of B, and thus repeats on 24 ends
            and 12 picks.


            Some Other Twills


            Curved Twill
            The principle of construction of curved twill can be understood
            from the design itself. It is used only to a limited extent as
            there is disadvantage that the length of the weft float and
            fineness of cloth may vary in direction so as to form curved
            effects.
            How to draw curved twill


            First make the base of curved twill. It is represented by o. We
            do it on 48x8 grid.




            Now complete the pattern with 4/4 twill :


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               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE



            Steep Twill
            Steep twills are those in which the angle of twill is more than
            45 degrees. The following is an example of steep twill:




            Here the base mark o represents the steps of twill. Overall the
            twill is 4/4.


            Low Twills
            Low twills are those in which the angle of twill is less than
            forty five degrees. The following is an example of a low twill.
            Again the base marks o represent the base of the twill.




            SUMMARY OF TWILL WEAVES
            Structuring Process


                         Interlaced with 2 or 3 warp yarns over and one or 2
            warp yarns under respective filling yarns.
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               PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE

            Identifying the weave
                         Diagonal rides formed left to-right or right to left.
            Performance characteristics
            Compared to plain weave, twill weaves have
               • Fewer interlacings and therefore more yarns per inch
               • More raveling
               • More pliable drape and hand
               • More wrinkle resistance
               • More resistance to showing soil and soiling
               • More durability and weight
               •   Tendency to have defined face and back
               • Twill direction defined as left or eight hand or variation
               • Angle of twill can vary from 15ºC to 75º with 45º typical.




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                PRIYANK GOYAL’S LECTURES ON FABRIC STRUCTURE

            Common fabrics by Identifying Characteristics

            Weight     Transparenc         Type        Surface/othe Name
                       y                   yarns       r

            Mediu      Opaque              Spun        Lightly             Challis
            m                                          brushed
                                                       surface

            Mediu      Opaque              Filamen     Balanced            Surah
            m                              t           reversible

            Mediu      Opaque              Spun        Balanced            Flannel
            m                                          revile              serge

            Mediu      Opaque              Spun        Balanced            Sharkskin
            m                                          yarn dyed           herring
                                                                           bone
                                                                           houndstoot
                                                                           h

            Mediu      Opaque              Filamen     Unbalanced          Lining twill
            m                              t

            Mediu      Opaque              Spun        Unbalanced          Jean,     drill
            m                                                              covert,
                                                                           chino,
                                                                           gaberdine

            Mediu      Opaque              Spun        Unbalanced          Denim
            m



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