Joining fabric pieces together by sewing produces both strength and flexibility in a seam. Seam and stitch types used in garment assembly must perform appropriately with the fabric types used and last throughout the lifetime of the garment. For example, it would be inappropriate to sew a swimsuit made from a knitted stretch Lycra fabric with a stitch type that had limited stretch characteristics, as this would cause the threads in the stitch to snap when the seams in the swimsuit were extended when the garment was worn.
Good appearance in a seam normally means smooth fabric joins with no missing or uneven stitches and no evidence of damage to the material being sewn. Gathers may occur, but this should be a style feature, therefore the amount of gathering and ease should be controlled.
A good seam appearance must be maintained throughout the lifetime of the garment despite damage caused by wear, washing or dry cleaning.
The seam must achieve the required standards of strength, elasticity, durability, security and comfort. The seam should be as strong as the fabric in both directions. Also, it should stretch and recover with the fabric.
With the increasing use of stretch fabrics in clothing today, the seam must be durable, must not irritate the skin in wear and must not fray or unravel.
The fabric and the end use of the garment determine the seam and stitch type that should be used. The needle which is used to pass the thread through the fabric also has to be considered. Needles come in a range of sizes with different points which are only suitable to use when sewing particular fabrics. For example, a needle with a smooth curved point, known as a ball point, should be used when sewing knitted fabrics.
- Class 100 Single Thread Chainstitches
- Class 200 All Hand stitches
- Class 300 Lockstitches
- Class 400 Multi-thread Chainstitches
- Class 500 Overedge Chain-stitches
- Class 600 Covering Chain-stitches
The most commonly used stitches are Overedge and Lockstitch.
There are three types of stitch within the Overedge classification. The Three Thread Overedge stitch (504), as shown in below, is used for neatening the edges of woven fabrics and joining seams on garments made from knitted fabrics. The stitch is formed from three threads, one needle thread and two looper threads which lash the edge of the fabric and prevent the fabric edge from fraying.
The Three Thread Overedge stitch (504) is an extensible stitch with excellent recovery properties and is used for neatening and joining seams in garments made from knitted fabrics. The width of an Overedge stitch is known as the stitch bight.
Owing to the narrow bight, which can vary from 4mm to 6mm, it cannot be used for joining seams on garments made from woven fabrics. This stitch is used for neatening woven fabric edges only.
The Four Thread Overedge stitch (514) is formed from four threads, two needle threads and two looper threads which lash the edge of the fabric.
The wider bight, from 6mm to 8mm, enables the stitch to be used for neatening fabric edges and joining seams in garments such as shirts made from lightweight woven fabrics as well as garments made from knitted fabrics, where good seam security is a vital characteristic of the seam.
The Five Thread Overedge stitch, frequently known as the Five Thread Safety stitch (516), is used for general seam joining in garments made from woven fabrics only.
This stitch is a combination of the Two Thread Chainstitch (401) and Three Thread Overedge (504) and is formed simultaneously on one sewing machine. It both neatens the edge of the fabric and joins the fabric edges together. The stitch cannot be used for joining seams in garments made from stretch fabric as the threads used in the Two Thread Chainstitch (401) will break once the seam is extended.
Within the Lockstitch classifi cation there are two main stitch types, the Lockstitch (301) and Zig Zag. The Lockstitch (301) is used for general joining of seams and topstitching on garments made from woven fabrics. When sewing woven fabrics, it is used for seam joining and attaching components such as a zip, as well as applications such as topstitching, sewing pin tucks and attaching binding to neaten a raw edge on a garment.
The seam is formed from two threads; one needle thread and a bobbin thread which interlace in the middle of the fabric plies being sewn. The stitch appearance is reversible; it is the same on both sides but it has insufficient stretch characteristics for seaming stretch knitted fabrics.
Seam Cross-section Diagrams
Seam diagrams which illustrate the fabric configuration in a seam can take quite some time to draw accurately; therefore a simplified version has been established. The simplified diagram shows the cross-section through the fabric which is represented using horizontal lines, and a short vertical line/s represents the point of the needle penetrating the fabric.
The Zig Zag Lockstitch (304) formation is similar to the 301 Lockstitch, but the Zig Zag formation makes this stitch more extensible and it can be used to sew stretch fabrics with low stretch characteristics. It is used for attaching elastic onto garments such as bras, pants and swimwear.
Single Thread Chainstick
There are two stitches within the Single Thread Chainstitch classification. The Single Thread Chainstitch (101) is used for temporary stitching, which is frequently referred to as Basting or Tacking. The Single Thread Chainstitch (101) is used to temporarily sew garments together for fitting purposes before permanent stitching, particularly in tailoring. This stitch is also frequently used to sew decorative effects such as pin tucks.
This stitch is formed from one single thread which is looped around the succeeding loop on the underside of the fabric. The stitch will easily unravel if the end of the row of stitching is not secured.
The Single Thread Blind stitch (103) is formed from one single thread and the sewing machine that performs this stitch has a curved needle which partially penetrates the outer fabric and then the hem edge. This secures the hem in position with no visible stitching to the face side of the garment. It is used for securing hems on garments such as trousers, skirts, dresses, unlined jackets and coats.
The Two Thread Chainstitch (401) shown below has the appearance of a Lockstitch on the face side but a looped eff ect on the underside. The threads link on the underside of the fabric therefore reducing the build up of threads in the middle of the fabric, which can alleviate seam pucker in densely woven fabrics. Although the stitch is slightly extensible, it can only be used to join seams made from woven fabrics and the stitch will unravel if the threads are broken.
It is used for joining long seams in garments, such as leg seams on trousers, and sewing lapped seams in garments where good seam strength and durability is critical, therefore it is frequently used in the construction of jeans and work wear garments. A lapped seam is also a decorative seam which is used to join side seams on ‘quality’ shirts. It is frequently known as a lapped felled seam. This seam is generally sewn using a twin-needle 401, Two Thread Chainstitch machine equipped with a folder which accurately laps the fabric edges over each other, enclosing them within the seam structure.
The Two Needle Chainstitch Bottom Cover (406) is used for attaching elastic on briefs, hemming and attaching binding onto garments made from knitted fabrics such as t-shirts.
The stitch is formed from two needle threads passing through the fabric and interlacing with a looper thread on the underside of the fabric.
Stitch types within this classification frequently are called Flatlock stitches.
The Two Needle Cover Chainstitch (602), which is a highly extensible stitch used for attaching elastic or securing hems on garments made from high stretch fabrics, such as underwear. There are 20cm of thread used in sewing 1cm of seam using this stitch. The stitch is formed from four threads, two needle threads and two looper threads.
The Three Needle Cover Chainstitch (605) is a more extensible stitch which is used for joining seams where the fabric edges are butted together or overlapped, and is extensively used in the construction of garments made from stretchy fabrics, such as swimwear, underwear and leisurewear. The stitch is formed from fi ve threads: three needle threads and two looper threads with 27cm of thread used to sew 1cm of the Three Needle Cover Chainstitch (605).
When selecting the appropriate seam type, the following aspects are considered:
- The appearance of the seam in the finished garment.
- Strength and durability of the seam. For example, lapped seams are used to sew work wear garments where areas of the garment are subjected to strain when the garment is worn, such as the back seat seam on a pair of jeans.
- The seam should feel comfortable when the garment is worn. For example, smooth, fl at seam constructions which do not irritate the skin should be selected when constructing underwear garments.
- Finally, the fabric characteristics will influence the seam selection. For example, French seams are used to sew lightweight fabrics only. The finished seam is pressed flat to one side; to this end, five plies of fabric are superimposed on top of each other; this would give a bulky seam if thick fabrics were used.
Generally, seams are used for:
- Joining fabric pieces together.
- Neatening raw fabric edges by:
2) attaching additional trimming or strips of fabric.
Open Lockstitch seams are used only when a component such as a zip is inserted on garments made from a woven fabric.
Both fabric edges are separately neatened using the Three Thread Overedge stitch, the right sides of the fabric pieces are placed together and joined using the 301 Lockstitch. The seam allowance is then pressed apart using an iron.
The French seam can only be used for joining lightweight fabrics for garments such as lingerie, evening wear, dresses, blouses, and skirts. A French seam is a complex seam and is therefore costly to produce and should not be used for joining seams on garments where garment cost is a critical factor. The seam is sewn using the 301 Lockstitch. The plies of fabric are fi rst sewn with the wrong sides of the fabric placed together, and then a second seam is sewn with face sides together, enclosing the raw edges of the fabric within the seam structure.
A closed seam is an economically constructed seam type used for joining garment pieces together.
The face sides of the fabric are placed together and the two plies are stitched together using one of the Overedge stitches.
The Three Thread Overedge (504) is used to create closed seams in garments such as t-shirts, underwear and sportswear made from knitted fabrics.
The Four Thread Overedge (514) closed seam is used for joining seams together when using knitted fabrics where good seam security is a vital characteristic. It can also be used for seaming garments made from lightweight woven fabrics when the seam is not subjected to any strain, such as the side seams on shirts or blouses.
The Five Thread Overedge (516) closed seam is used for seaming garments made from woven fabrics only, such as joining the side seams on skirts, trousers and dresses.
A lapped seam as aforementioned is classifi ed as a joining seam. This seam is generally sewn using a twinneedle (401), Two Thread Chainstitch machine equipped with a folder which accurately laps the fabric edges over each other, enclosing them within the seam structure.
A lapped seam is frequently known as a lapped felled seam. It is used in garments where good seam strength and durability are critical, and is frequently used in the construction of jeans and work wear garments. This seam type is also a decorative seam which is frequently used to join side seams on ‘quality’ shirts.
Neatening Raw Fabric Edges
There are a variety of diff erent methods that may be used to neaten the lower edge of a garment. The depth of the hem is determined by the garment style, fabric, cost and whether the hem is straight or curved.
A single turn hem, as shown in Figure 43, is used for hemming garments made from woven fabrics only. The fabric edge is neatened using the Three Thread Overedge stitch and then the hem is turned over by the desired amount and the hem is secured in position with the Lockstitch (301).
The width of the hem turning is determined by the shape of the fabric edge being hemmed; for example, if the edge of the fabric is curved, the hem allowance turning should be 1cm or less, whereas if the fabric edge is straight, the hem allowance turning can be more substantial.
In a double turn hem the fabric edge is turned over and turned over again then secured in position with the 301 Lockstitch machine which is equipped with a folder to double turn the fabric edge. As described above, the hem turning width is determined by the shape of the fabric edge being hemmed.
Hems on garments such as trousers, skirts, dresses, unlined jackets and coats can also be neatened using the Single Thread Blind stitch (103).
Binding is a decorative method used to finish off a neckline or armholes on garments.
The hem of a garment made from lightweight flimsy fabric can be difficult to neaten using the methods described previously. With a rolled edge hem, the hem is neatened using the Three Thread Overedge (504).
The stitch density is increased and the stitch bight is reduced to approximately 3 mm, providing a decorative finished edge.