Comparison of Seam Strength between Dyed and Un-dyed Gabardine Apparels: A research on Lapped & Superimposed seam.

Today is the golden age of fashion. Fashion garments and apparel has been used everywhere to cope with the fashion era. These fashion garment and apparels are made of the fabrics of various structures and components through various processes. Among them gabardine is one of the most remarkable type of fabric and apparel dyeing is the latest process used for fashion apparel. We are going to have a look into the seam strength variations between dyed and un-dyed gabardine apparels after conceding the garment dyeing process. It is a comparative research work which will deliver us very effective knowledge about various types of seam, seam strength and seam performance. For comparative study many dummy apparels body have been produced as samples which are dyed in Hams washing and dyeing limited. After that all samples have tested in Thermax woven dyeing laboratory. Since Bangladesh is a very potential fashion market and the fashion garments are being manufactured more and more. Hence the fashion trend is rapidly going to garments dyeing from conventional fabric/yarn dyeing processes. Gradually garments dyeing order are increasing higher to higher.


INTRODUCTION
Apparel is one of the fundamental needs of mankind's living. So it's being got more and more priority day by day. This basic apparel has come up to the fashion today with the chronological evolution of fashion. Apparel or garment industry includes a diversity of these fashion products to meet up the demand. Now-a-days the latest technologies are being applied in apparel industries. Today's fashion and apparel market is highly competitive and to sustain in this market, fashion producers mainly rely on the quality issues not on prices merely. And from this aspects raw material properties, sewing performance and seam quality becomes very important. Fabric and sewing thread is the basic raw material of apparel industry. Characteristics of the raw material influence the seam quality of the garment. The apparel designers are primarily interested in the raw material properties for high seam quality and consumer is mainly interested in appearance, comfort, and wears ability of the garment. Proper selection of raw material not only gives comfort to the wearer but also helps in smooth working of manufacturing process and lead to defect free garment. A large variety of sewing threads is used in clothing industry. The majority of the sewing threads used by the clothing industry are made from cotton and polyester fiber [1]. Threads made from natural fibers such as linen and silk and certain manmade fibers, for example nylon, acrylic and viscose are also used in clothing industry [2].
Many factors influenced the quality of seams. These factors can be classified into four principal origins: Speed, needle, thread and fabric. It was found that fundamental interactions between these factors still exist [3]. For the purpose of making good seam, great number of techniques has been developed until today but nothing has been as successful as sewing process. Stitch is placing the sewing materials like fabrics with in and out by needle. Different stitches and stitch types are being used for flexible materials like knitted apparels and suits; they are being used f or less flexible knitted products and for sewing relatively inflexible materials like woven fabrics as well. Despite of recent developments on automation of general set up; sewing threads are still irreplaceable material in apparel sector. The mistakes arisen from the sewing threads having been eliminated by new studies which performed by manufacturers. As a result of technological developments: smooth, steady and strong sewing threads provide advantages for all stitch types [4]. SeamA seam is a method of joining two or more pieces of materials together by a row/ series of stitching. The purpose of most of these seams is purely functional and can be called as constructional seams. Straight, neat, smooth, even seams that are not twisted, ropey, or rippled contribute to aesthetics of the garment/apparel. According to British Standard 3870, there are eight types of seam,  Class 1 (superimposed seam)  Class 2 (lapped seam)

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Seam Class 1 (Superimposed seam):These generally start with two or more pieces of material superimposed over each other and joined near an edge, with one or more rows of stitches. There are various types of seams within this class. A superimposed seam can be sewn with Stitch Types 301 or 401 to create a simple seam. The same seam type can also be sewn with Stitch class 500 (Over edge stitch) or Combination stitches (e.g., Stitch class 516) [6].

Seam Strength
The seam strength of a sample refers to the force acting upon a seam, at the time of fabric failure along the line of needle penetration. Seam strength refers to the load required to break a seam. Two pieces of woven fabric are joined by a seam and if tangential force is applied the seam line, rupture ultimately occurs at or near the seam line. Every seam has two components, fabric & sewing thread. Therefore, seam strength must result from the breakage of either fabric or thread or in more cases, both simultaneously. Research has revealed that the load required to rupture the seam is usually less than that required to break the unsewn fabric [

Gabardine:
Gabardine is a tightly woven warp-faced twill weave fabric. Warp-faced fabrics have more warp or lengthwise yarns on the surface of the fabric than filling or crosswise yarns. Twill weave fabrics show a diagonal wale, or raised line, on their surface. The fine wale is closely spaced, slightly raised, distinct, and obvious only on the fabric's face. The wale angle in gabardine is 45 or 63 degrees. Gabardine always has many more warp than filling yarns, often twice as many warp yarns as filling yarns. Fabric weights range from 7 ounces per square yard to 11 ounces per square yard. Fabric density ranges from 76 warp ends per inch (epi) by 48 filling picks per inch (ppi) to 124 epi by 76 ppi. The combination of the weave structure, yarn size, and warp to filling ratio creates the wale angle. A steep (63 degree angle) twill gabardine is often used in men's wear while a regular (45 degree angle) twill gabardine is often used in women's wear.
In the most common interlacing patterns the warp crosses two filling yarns before going under one filling (2 x 1) or the warp crosses two fillings before going under two fillings (2 x 2) to create right-hand twills in which the wale line moves from the lower left to the upper right. Garment/Apparel dyeing Garment Dyeing or piece dyeing means that garments are sewn "raw" and dyed only after sewing. Garment dyeing is increasingly fashionable; many collections are garment dyed especially trousers. The unmistakable look is much appreciated. At the same time Garment Dyeing allows high levels of flexibility regarding colors, logistics, materials management and therefore supply. Most important fiber for Garment Dyeing still is and will be cotton. But elastic fabrics get more and more important.
With regard to the sewing thread, special considerations are necessary to keep the quality of the seam at the usual standard. Sewing threads with good dyeing properties, sufficient strength and optimal sew ability are needed.

RESULTS AND DISCUSSION Effect of the types of Seam & Stitch on Seam Strength
There is a significant difference of seam strength between un-dyed & dyed samples for both lapped & superimposed seam. Table 5 shows the loss of seam strength between un-dyed and dyed samples. In case of gabardine apparels, the loss of seam strength of dyed lapped seam is varying from 5 to above 10 in percent.    Table 6 shows the loss of superimposed seam strength between un-dyed and dyed samples. In case of gabardine apparels, the loss of superimposed seam strength is varying from above 9 to 13 percent shown in table 6. The loss of seam Strength of superimposed seam is higher than lapped seam. Here it has been found that the superimposed seam strength always less in dyed samples. As per figure 6, it has been clearly observed that the difference of seam strength or the loss of seam strength between un-dyed & dyed samples.

Superimposed Seam
By comparing 2 tables (table 5 & table 6), the loss of seam strength is not equal between lapped seam & superimposed seam. The loss of seam strength of superimposed seam is always higher than the lapped seam which can be representing by line diagram in figure 7. Both of lapped and superimposed seam shows the fluctuated trend of loss of seam strength after apparel dyeing. Lapped seam shows downward fluctuated trend whereas superimposed seam shows upward increasing trend.

Remarks
For lapped seam, the loss of seam strength between un-dyed & dyed samples is more or less 5-10% For superimposed seam, the loss of seam strength between un-dyed & dyed is more or less 9-13% It is noticeably observed that the loss of seam strength of superimposed seam is higher than the lapped seam.

CONCLUSION
At the end of this research work, we can conclude that, seam strength of dyed apparels is less than that of un-dyed apparels. It is because of undergoing various stages in dyeing process. Different factors of sewing influence the seam strength on dyed apparels individually. The performance of apparels mainly depends on seam and stitch as well as different sewing factors. Here we also found that loss of seam strength for lapped seam is less than that of superimposed seam. So the fashion apparels in which lapped seam is mainly used, are more durable. To cope with the modern fashion era, we have to go through the fashion garments/apparels. And we also need to concentrate on the processes involved in making this fashion garments.