What is Selvedge in Fabric?
The warp-way strips that form the edges of the fabric are called selvedges or selvages. It is well-known fact that selvedges are necessary for any type of fabric. Selvedges provide strength to fabric for the subsequent handling. It binds the extreme outer ends of warp yarn with the weft to prevent the cloth fraying. A firm, smooth and perfect selvedge is necessary for further processing of fabric and for future end use in some cases. The thickness of the selvedge should be the same thickness as the fabric as for as possible. If the selvedges are too thick, they lead to damage during calendaring.
The selvedge prevents the fabric from ravelling and the edges from tearing when the fabric is under the stresses and strains of processing. Normally, the selvedge area is made stronger than the body by using: heavier warp yarns; more warp yarns per inch; plied warp yarns; greater twist for spun yarns; and different weave.
Different Types of Selvedge in Fabric:
There are four main types of selvedges:
- Conventional or shuttle selvedge
- Tucked-in selvedge
- Leno selvedge
- Fused selvedge
A. Conventional Or Shuttle Selvedge:
In shuttle loom, the shuttle carries the same weft yarn during its return movement without cutting the weft at the edges. Therefore the weft binds the warp yarn at the edges with the body of the fabric. The shuttle selvedges are strong and smooth and look clean and uniform. It is the best selvedge of all other selvedges. Figure 1 shows a shuttle selvedge. A few extra warp threads are necessary to produce strong selvedges. The width of the selvedge may vary from 10mm to 15mm.
B. Tucked-in Selvedge:
In the shuttleless looms, both ends of the weft yarn are cut, and therefore, they do not bind the warp threads at the. edges along with the body of the fabric. While cutting the weft at both ends, a length of about 10mm to 15mm is left as fringe. This projecting weft tail is turned and woven back into the body of the fabric by a special mechanism in the form of a hairpin during the next picking. This tucking in of the weft tail at both edges of the fabric leads to the formation of selvedges. This selvedge is called a tucked-in selvedge. In tucked-in selvedge, the density of the weft yarn at the selvedge area is double. Next to conventional selvedge, tucked-in selvedges are good performers. The disadvantage of tucked-in selvedge is its initial cost for the tuck-in mechanism. Almost all types of shuttleless weaving machines use tucked-in mechanisms. Figure 2 shows a tucked in selvedge.
This system is generally used for light to middle weight fabrics, when weave and fabric density permit. There are also available tuck-in selvedge motions which are entirely controlled by pneumatic or mixed pneumatic and mechanical devices.
C. Leno Selvedge:
Leno selvedges are formed by leno design at the edges of the fabric. Fabrics with leno selvedge has fringe edges which are less attractive. However, leno selvedges are most suitable for all shuttleless weaving machines. In half-cross leno selvedge, two leno threads run in opposite directions around the standard end, thus binding each pick on both sides of the standard end as shown in Figure 3.
A full-cross leno selvedge is made by twisting two leno threads continuously together and inserting the weft between them. A full leno selvedge is formed by a rotating disc, which has two fanged bobbins at the rear of the healds. The sequence of selvedge formations is shown in Figure 4.
D. Fused Selvedge:
The outer ends of the warp are fused with the weft at the selvedges by means of heaters. This is called a fused selvedge. Fused selvedges can be formed only when weaving thermoplastic filaments yarn such as polyester, polyamide and polyolefin. The edges of the fabric are heated, causing the fibers to melt and fuse together. Fused selvedge is harsh and stiff.
Importance of Selvedge in Fabric:
- The selvedge is tightly woven to ensure the threads from unraveling. It helps in determining the fabric’s lengthwise grain, essential for accurate pattern layout in garment construction.
- Selvedge makes easier to handle during cutting and sewing.
- Often printed with information such as the brand, pattern name, or fabric width.
- In selvedge denim, it is a design element, often used in fashion to showcase quality craftsmanship.
- The clean edges allow maximum use of fabric width without needing additional finishing.
Problems of Selvedge in Fabric:
If the selvedge warp yarns have greater shrinkage during the finishing process, a tight selvedge occurs, resulting in the puckering of an area near the fabric edge. This will be a problem when the material is spread on the cutting table where the cloth does not lie flat. Cutting off the selvedge to eliminate the stress on the fabric can eliminate the tight selvedge problem. The loose edge can either be fused, if the fabric is thermoplastic, or glued by adhesive to prevent unravelling. If the tight selvedge problem is only noticed when the fabric has been laid on the cutting table, the puckering can be eliminated by cutting into the selvedge every six inches to twelve inches, allowing the cloth to relax, although of course, this will generate higher cutting wastage.
Conclusion:
Selvages (also called selvedges) provide strength to fabric for safe handling of the fabric. Selvage should not curl. The weaving machines need mechanisms which through the formation of sufficiently strong selvedges bind the wefts together, thus imparting to the fabric a proper appearance and solidity and preventing the breaking up of the threads on the fabric edges during the subsequent operations. In shuttle looms, there is no need for special selvage; since the yarn is not cut after each filling insertion, the edges of the fabric are smooth and strong. In shuttleless weaving, since the pick yarn is cut after every insertion, there is fringe selvage on both sides of the fabric. In this case, special selvages are needed to prevent slipping of outside warp yarns out of the fabric.
References:
- Fabric Manufacturing Technology: Weaving and Knitting by K. Thangamani and S. Sundaresan
- Handbook of Weaving by Sabit Adanur
- Reference Books of Weaving (ACIMIT) by Giovanni Castelli, Salvatore Maietta, Giuseppe Sigrisi, Ivo Matteo Slaviero
- Textile Handbook By The Hong Kong Cotton Spinners Association
- Advanced Woven Fabric Design By Dr. J. Hayavadana
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