Seam Defects in Garments: Causes and Remedies

Seam Defects in Garments

Seam defects refer to imperfections in the stitching or construction of garment seams, which can affect the appearance, durability, and overall quality of the product. Many quality issues and defects can arise in garments during the sewing process. Defects in assembling include defects with both stitches and seams. Seam quality problems or defects can be time-consuming, frustrating and costly to a manufacturer. Possible stitch defects include needle damage, feed damage, skipped stitches, broken stitches, wrong or uneven stitch density, balloon stitches, broken threads, clogged stitches, hangnail, and improperly formed stitches. Possible seam defects include seam grin, seam pucker, incorrect or uneven width, irregular or incorrect shape, insecure back-stitching, twisted seam, mismatched seam, extra material caught in seam, reversed garment part, wrong seam type used, slipping seam, and wrong thread used. The major stitch or seam quality problems or defects associated with the garment manufacturing process are discussed in this article.

Stitch Defects in Garments: Causes and Remedies

Common stitch and seam defects are discussed with causes and remedies.

A. Drop stitch / Skipped stitches:
Skipped stitches occur when the sewing machine fails to form a complete stitch, leaving gaps in the seam. They are caused when the sewing thread partially skips and stitching is not performed completely. They are usually caused by an old or worn needle.

Causes:

1. Bobbin hook or looper does not enter thread loops at the correct time
2. Thread loop failure caused by incorrect needle size/style for the particular thread size/type
3. Thread loop failure because thread control mechanism is incorrectly set, thereby leading to thread loop starvation
4. Fabric flagging due to improper presser foot control or larger throat plate hole
5. Deflection of needle
6. Improper loop formation of thread

Remedies:

1. Check the machine clearances and the timings
2. Check if the needle is inserted and aligned correctly
3. Change the needle size/style
4. Restart and check loop formation
5. The presser foot pressure should be checked and readjusted if necessary
6. Change the throat plate to match the needle size
7. Readjust tensions

B. Broken stitches
Broken stitches are caused by the selection of wrong stitch type, too tight thread tension, excessive pressure and machine speed.

Causes:

1. Excessive thread tension causes thread breakage during sewing.
2. Incorrect needle size or type leads to improper stitch formation and breakage.
3. Weak or low-quality thread cannot withstand sewing stress.
4. Fabric stretching during sewing puts strain on the stitches.
5. Needle deflection due to high-speed sewing causes skipped or broken stitches.
6. Improper seam finishing results in weakened stitches.
7. Mechanical issues like burrs on the needle, throat plate, or bobbin case damage the thread.

Remedies:

1. Adjust thread tension to prevent excessive stress on the thread.
2. Use the correct needle size and type suitable for the fabric and thread.
3. Select high-quality, durable thread to withstand sewing stress.
4. Control fabric handling to minimize unnecessary stretching.
5. Reduce sewing speed to prevent excessive needle deflection.
6. Apply proper seam finishing techniques to strengthen stitches.
7. Inspect and smoothen any rough edges on the needle, throat plate, or bobbin case.

C. Staggered stitches
Stitch is not parallel produced by needle. Staggered stitches can be caused by yarns in the fabric deflecting the needle away from a straight line of stitching, giving a poor appearance. In some hard, woven fabrics, really straight stitching will only be achieved at a slight angle of bias.

Causes:

1. Needle vibration or deflection
2. Incorrect or blunt needle point
3. Incorrect needle-to-thread size relationship
4. Improper fabric control and bouncing of presser foot

Remedies:

1. Needle size can be increased or tapered needle can be tried
2. Either sewing needle or sewing thread can be changed
3. Can go for positive sewing feed mechanism

D. Variable / Uneven stitch density
Uneven stitch density arises when stitching is not performed straight and the machine is not controlled properly. It may occur from insufficient foot pressure in a drop feed system, causing uneven feeding of the fabric through the machine. It can occur particularly with materials with a sticky or slippery surface. Pressure must be adequate to enable even feeding, but with many fabrics and sewing situations, specialized feed systems are necessary to achieve even feeding of all the plies of the material. Operators may be able to contribute to consistency in stitch density by sewing at a constant speed, rather than in bursts.

Causes:

1. Improper control of fabric feed
2. Twisting of thread in thread guide
3. The incorrect unwinding of thread form package during sewing.
4. Excessive tension of the thread.

Remedies:

1. Increase the foot pressure
2. Can go for positive sewing feed mechanism

E. Seam grin
Seam grin is the defect when stitch opens due to insufficient sewing thread tension. This weakens the seam and affects the overall quality of the garment.

Causes:

1. When two fabric panels are opened at opposite sides of one another to the seam, a gap is revealed between the two fabric panels

Remedies:

1. Increase stitching tensions
2. Stitches per inch (SPI) can be increased

F. Seam pucker
Seam puckering is one of the most common problems associated with lightweight fabrics. It is an unequal crinkling or a gathering of the seam.

Causes:

1. Incorrect thread tension leads to uneven gathering of fabric.
2. Uneven fabric feed due to poor synchronization between feed dogs and presser foot.
3. Fabric shrinkage after sewing causes distortion in the seam.
4. Improper stitch density with too many stitches per inch results in excessive gathering.
5. Mismatched needle and thread size/type affect stitch formation.
6. Differential fabric stretching during sewing creates puckering.
7. Improper bobbin tension leads to uneven stitch balance.

Remedies:

1. Adjust thread tension to balance upper and bobbin threads.
2. Check and adjust the fabric feeding mechanism, including presser foot pressure.
3. Pre-shrink fabric before sewing to prevent post-sewing shrinkage.
4. Reduce stitch density to minimize excessive gathering.
5. Use the correct needle and thread for the specific fabric type.
6. Control fabric stretch with stabilizers or adjust differential feed settings.
7. Check and adjust bobbin tension for consistent stitch formation.

G. Seam slippage
Seam slippage is the separation or pulling apart of yarns in a fabric, usually along a sewn seam or join. It is the tendency of the warp and weft yarns in a woven fabric to slip over one another. Seam slippage is caused by the slippage of the upper and lower fabric with respect to each other. In some apparel, before seam failure occurs, enough yarn slippage (filling yarns shifting over warp yarns or vice versa) develops to render the apparel unusable, because such failure is not readily repairable by seaming. Seam slippage is measured by subtracting the elongation of the fabric from the elongation of the fabric with a seam in it. The difference is indicated as seam slippage, which can be considered one form of failure of seam assembly.

Causes:

1. This happens when the yarns in the fabric are pulled out of the seam and are more frequent in fabrics made from continuous filament yarns

Remedies:

1. French seam type can be tried
2. Seam width can be increased
3. Stitch density should be optimized

H. Needle thread breakage
Thread breakage is one of the most frustrating problems to a machinist. If the thread breaks during the sewing of a seam, the thread has to be unpicked and the seam sewn again. This is because the joining of the stitch must not be seen on the face of the garment, as this would compromise the aesthetics of the garment.

Causes:

1. Thread gets trapped at the thread guide
2. Snarling of thread before tension disc
3. Excessive needle thread tension
4. Irregularities or damages in needle guard, throat plate, bobbin case and needle eye
5. Excessive needle heat, groove or eye blocked with melted fabric
6. Overheating of hook
7. Quality of needle thread is inferior

Remedies:

1. Use a foam pad or a similar device to prevent the package from tilting
2. Ensure that the rethreading is done correctly
3. The needle thread tension can be reduced and the condition of the disc tensioner should be checked
4. Replace the needle with one of better quality
5. Change to a correctly finished thread of a better quality

I. Bobbin/looper thread breakage
Bobbin or looper thread breakage occurs when the lower thread (bobbin or looper thread) breaks during sewing, causing the machine to malfunction and the seam to become incomplete. This defect can lead to weak seams, stitching interruptions, and delays in production.

Causes:

1. Bottom thread not wound properly on the bobbin
2. Bottom thread tension is very high
3. Damages in bobbin case, looper eyelet
4. Improper fitting of bobbin case

Remedies:

1. Adjust the alignment of the bobbin winder
2. Adjust the bottom thread tension
3. Polish the edges and the correct surfaces of bobbin hook and case

J. Thread fusing:
Thread fusing occurs when the sewing thread melts or sticks together due to excessive heat, friction, or improper thread selection.

Causes:

1. Incorrect sewing thread
2. Poorly finished woven fabric
3. Damaged needle or overheating of needle

Remedies:

1. Use better quality sewing thread
2. Change to more suitable needles.
3. Apply needle coolants

K. Imbalanced / variable stitching
Imbalanced stitches in lock stitching can reduce the potential for stretch in a seam in a knitted fabric. Unbalanced seams are often recognized by low extensibility leading to cracking. It occurs when the stitches on a seam are inconsistent in size, tension, or appearance.

Causes:

1. Incorrect sewing tensions
2. Incorrect threading
3. Needle thread getting snagged on bobbin case or positioning finger
4. Variable tension caused by poor thread lubrication

Remedies:

1. Check for snarling, adjust the thread tension
2. Rethread the machine
3. Polish the bobbin case surface
4. Reset the positioning finger and the opening finger, if fitted
5. Switch to superior quality threads from coats

Conclusion

Stitch defects in garments can significantly impact their quality, durability, and appearance. These stitch defects occur from various factors, including improper machine settings, improper thread tension, incorrect thread and needle selection, fabric characteristics, and operator faults. By implementing the right techniques and regular inspections, manufacturers can reduce stitch defects, improve garment quality, and enhance customer satisfaction.

You may also like: Different Types of Seams in Sewing and Their Properties

References:

[1] Karthik, T., Ganesan, P., & Gopalakrishnan, D. (2016). Apparel Manufacturing Technology. In CRC Press eBooks. https://doi.org/10.1201/9781315367507

[2] Sinclair, R. (2015). Textiles and fashion : materials, design and technology. In Woodhead Publishing

[3] Garment Manufacturing Technology. (2015). In Elsevier eBooks. https://doi.org/10.1016/c2013-0-16494-x

[4] Majumdar, A., Das, A., Alagirusamy, R., & Kothari, V. (2012). Process control in textile manufacturing. In Woodhead Publishing Limited eBooks. https://doi.org/10.1533/9780857095633

[5] Kiron, M. I. (2021a, February 5). Seam defects | Common seam quality defects in garments. Textile Learner. https://textilelearner.net/common-seam-quality-defects-in-garments/

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