This is plain weaves in which two or more ends weaves together as one. To form weft rib the thick picks always pass over or under two or more thick or fine ends. Here the plain weave is extended for two ends as illustrated for 2-2 filling rib & a 3-1-1-3 filling rib below;
Weft rib is the amplification in width of plain weave. If the number of lifted or lowered yarns in each shed opening is identical, weft rib is designated as regular; in the opposite case, it is designated as irregular.
|Figure 4: Weft Rib|
Regular weft rib weave:
The number of yarns lifting or lowering in the even shed does not exceed 4. Therefore, there exist only 3 regular weft ribs: the weft ribs 2-2, 3-3 and 4-4.
|Regular weft rib weave|
As for the warp rib, there are three types of irregular weft ribs:
- The varied weft rib
- The interrupted weft rib
- The varied-interrupted weft rib
|Irregular weft rib weave|
This structure, with its characteristically intricate patterns, has been used primarily for decorative borders--both on flatweaves and on the skirts of knotted-pile objects. It is not actually an 'end finish,' however. In a complementary-weft weave, weft yarns of contrasting colors are used in pairs, and each weft complements the action of the other exactly. If a light weft passes over four warps and under two, its dark-colored companion follows, passing under four warps and over two. The sequences are changed to vary the patterns: some wefts might go over and under 3 warps, or they might go over 5 and under 1, but they are always used in complementary pairs. All wefts are allowed enough ease to cover the warps completely, making this a weft-faced weave. When only two colors are used, the back and front faces are similar. The interlacement pattern is the same on both; the position of the colors is merely switched. Small X's, for example, may be light on one face and dark on the other. Typical patterns are very small: little triangles, diamonds and rosettes predominate. The blocky Qashqa'i so-called 'domino' border features one of the more complex motifs. Warps of two different colours are set up in two complementary sets that are integral to the structure of the fabric. Unlike supplementary weft, there is no ground cloth on top of which the pattern is created. Each warp has its counterpart on the opposite face of the cloth, and the design is achieved from the two sets of warps interlacing with the weft. The result is a design with the colours in reverse on each face.
Explain the Various Methods of Designation of Twill Weave and Give Reasons for the Construction of This:
Twill weaves are constructed upon any given number of threads exceeding two. The interlacing order of threads in the repeat in twills weaves is identical & the diagonal line is formed by advancing this order in step of one in either direction.
Twill weaves can thus be designated by describing the interlacing of the first threads; using the following methods;
- 2 up; 2 down
- 2-& -2
Thus for irregular twills the designation might be;
- 1 up; 3 down; 2 up ; 2 down
- 1-& -3 ; 2-& - 2
- They are used for ornamentation purposes.
- They are constructed for enabling cloth of greater weight; closer settings & better draping quality.
- Generally dimond,diaper and zigzag twill are used for making pillow,cover,screen,unpholstery,bed sheet,towel etc.
- Continious twill are used for making fabric for shirting,suiting and pantin (denim, gaverdine).
- For making various type of ornamental cloth,other derivatives of twill weave are used.
- Hearing bone twill are used in the cloth of suiting and overcoats.