What is Seam Puckering? Types, Causes and Remedies

What is Seam Puckering?

Seam quality problems can be time-consuming, frustrating and costly to a manufacturer. There are many types of problems associated with the quality of seams on a product. One of the most common problems associated with lightweight fabrics is seam pucker. Seam puckering is defined as seam gathering during sewing or after sewing, or laundering of garments, leading to an unacceptable seam appearance to the garment. Seam puckering consists of ridge, wrinkle or corrugation of the material, or a number of small wrinkles running across and into one another, which appear on sewing together two pieces of fabric. Seam pucker is regarded as a matter of primary concern in garment manufacture. When the sewing parameters are not appropriate to the material selected, puckering occurs along the garment seams, and the aesthetic appeal of the garment deteriorates.

Seam puckering is more frequent on woven fabrics than knitted fabric. It is prominent on tightly woven fabrics. Seam puckering is typically occurred due to the displacement of the fabric caused by the stitching action, since lockstitch involves the formation of stitches within the material.

Pucker is common in lightweight materials such as shirting, blouses and microfiber fabrics. These materials are less able to withstand the forces of the needle and sewing thread due to their more flexible nature. Seam pucker also presents problems in fabrics used in producing skirts, trousers and suits.

Seam puckering depends on sewing-thread properties, stitch length and type, thread tension, sewing speed, presser foot pressure, needle size, and frictional properties of the fabric and its constituent yarns.

Types of Seam Puckering with Causes and Remedies:

There are several types of seam puckering. Seam puckering is typically caused by the following conditions:

1. Inherent puckering (structural jamming)
2. Tension puckering
3. Machine puckering
4. Shrinkage puckering

1. Inherent Puckering or Seam Puckering Due to Structural Jamming:

Seam puckering is more common on tightly woven fabrics (high thread density) since the yarns are aligned in very tight layers that could not move easily to compensate for the sewing thread as it is introduced into the seam. In case of densely woven fabrics, there could be insufficient space to accommodate a sewing thread without displacement of yarns. Hence, stitching along a straight line will distort and push the adjacent yarns in the fabric, which cause the seam to pucker and is commonly known as ‘structural jamming’ or ‘inherent pucker’ as shown in Figure 1.

To check whether the defect is due to structural jamming, sewing threads should be cut between nearby needle penetrations through the seam line and have to be observed whether the seam puckering exists in the fabric. If the seam puckering is noticed even after the cutting of sewing threads, then yarn displacement is the possible cause as shown in Figure 2.

Inherent puckering is the hardest to eliminate as it is caused by the displacement of the warp and weft yarns by the needle penetrating the fabric and inserting the thread. If sewn in the warp direction, the warp threads will be displaced laterally, causing an inevitable shortening of their length relative to the adjacent yarns. The fabric structure becomes jammed, resulting in swelling and puckering of the seam.

Factors that should be addressed in attempting to eliminate inherent pucker include:

• Choice of needle and thread – the finer the needles and threads, the less the risk of inherent pucker.
• Choice of needle plate – fine-holed needle plates are essential for reducing seam pucker.
• Choice of stitch type.
• Operator handling skills.
• Sewing direction.

Remedial Measures for Structural Jamming:

• Use of finer sewing thread which will retain sufficient seam strength.
• Use of finer needles that will not lead to sewing problems.
• SPI (stitches per inch) should be reduced, hence less yarns are exiled from the stitch line.

2. Tension Puckering:

Tension pucker results from incorrect thread tension and/or incorrect needle choice (Figure 3). The tension must be as slack as possible to produce a well-balanced stitch, and the smallest-diameter needle possible with the correct needle point type for the fabric should be used. The sewing threads must suit the seam position and the thread must be the minimum diameter possible to minimize disruption within the yarns of the fabric whilst still maintaining the strength of the seam.

Other factors that can affect tension pucker are the extension properties of the sewing thread and the possibility of shrinkage due to moisture and heat. The yarn twist of the sewing thread and frictional properties can both have a significant effect on the regularity of stitch inter-looping and seam appearance.

If a sewing thread tension is higher in the seam, it will be in stretched condition during the stitching process and it will try to relax after sewing. This leads to seam puckering instantly as the seam is coming out from beneath the presser foot. This incident also happens after the garment is laundered causing the seam to pucker. Excessive sewing thread tension will not only lead to seam puckering but also cause other problems such as skipped stitches and sewing thread breakage.

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To check whether the puckering is due to structural jamming or thread tension, the top and bottom threads of all stitches along a seam have to be cut for a few centimetres, without displacement of yarns in the fabric. If the seam pucker is disappeared over this length, then it was caused by sewing thread tension and subsequent recovery as shown in Figure 4.

Remedial Measures for Tension Puckering:

• Optimize needle thread and bobbin thread tensions.
• Synchronisation of timing of feeding has to be set correctly as incorrect feed timing can lead to the need to apply excessive tension to the needle thread, in order to create a properly balanced stitch.
• Positioning finger should be set correctly to permit the sewing thread to go through the bobbin hook easily in case of lock stitch machines.
• Stitch balance should be adjusted on chain stitch machines in a manner that the needle loops on the bottom side of the seam lay over at least halfway to the next needle penetration when the looper thread is unravelled out of the seam.

3. Feed Puckering:

The shortening of one of the fabric layers (usually the bottom one) creates a wavy appearance on one side and results in what is known as feed puckering. This problem occurs when two plies of fabric to be joined are not fed uniformly through the sewing machine. The bottom ply is usually fed more positively by the feed dogs, while the top ply is only held and guided by the presser foot (Figure 5).

A great variety of feed mechanisms have been developed to try to improve feed pucker. Along with selecting the right feed system for the fabric and seam, tilting the feeder to provide the desired result on the seam may also help, but this adjustment can only be undertaken by a skilled sewing machine engineer.

It occurs when different fabric plies are fed at variable rates than one another. This leads to a gathering effect in the over-fed ply. Ply mismatching of fabric plies as shown in Figure 6 occurs.

• When the presser foot holds back on the upper fabric ply as the bottom fabric ply is being fed at a greater rate by the feed dog
• When the operator grips the bottom fabric ply but shoves the top fabric ply to the seam line hence the fabric edges will come out evenly.

To identify the feed puckering, two perpendicular cuts across a sewn seam have to be done where the puckered condition is the maximum. Then, the sewing thread has to be removed from the seam and ensure whether two fabric plies are of equal length. If one fabric is longer than the other, then the puckering is being caused by the uneven feeding of fabric.

Remedial Measures for Feed Puckering:

• The presser foot pressure exerted on the fabric should be less to keep up uniform feeding. The clamping of fabric by the presser foot should be ensured at the front as well as the back of the needle.
• Setting of feed dogs with respect to their height as well as back feeding should be ensured. The selection of feed dog with reference to the number of teeth per inch and number of rows of teeth should be done. The feed dog with 20–24 TPI (teeth per inch) for lightweight fabrics, 14–18 TPI for medium weight and 8–12 TPI for heavy weight fabrics are normally preferred.
• The presser foot and needle plate should have comparatively small needle holes with respect to the needle size being used.
• Sewing machines equipped with more positive feeding mechanisms are advisable.

4. Shrinkage Puckering:

Shrinkage puckering could happen when one fabric panel in the seam shrinks differently compared to the other fabric panel as shown in Figure 7. Typical components include the base fabric, interlining, zipper tapes, stay tapes and the thread. All these components should have minimum shrinkage to produce a pucker-free seam.

• Wash pucker: If the sewing thread shrinks during the washing process, it pulls the fabric with it causing puckering and is more prominent with the use of cotton sewing threads.
• Ironing pucker: It occurs while using synthetic sewing threads in the garment. The application of heat changes the molecular structure of the fibers in the thread, which results in shrinkage leading to puckering.

To identify the shrinkage puckering, two perpendicular lines at a distance of 10″ across a seam should be marked using an indelible ink pen that normally shows extreme seam puckering after laundering. Two perpendicular lines against the seam line which has been marked before should be connected with a line running parallel to the seam. The length of the seam should be verified after the garment is subjected to finishing and pressing cycles. The gap between the two marked lines will be less than 10″ if there is seam shrinkage. To minimize this puckering, the sewing thread having low shrinkage characteristics has to be selected.

Stitch Density and Fabric Type:

Pucker induced by stitch density and fabric type should also be considered when studying tension pucker. It is directly linked with thread tension and the length of thread required by the seam. Increasing the thread consumption in the seam increases the seam strength. In a lockstitch, for example, a 3% increase in stitch consumption can give an almost 60% increase in seam strength.

However, a stitch is only complete after the fabric has moved past the needle. The fewer stitches per centimetre, the greater the distance the fabric must be moved for the next stitch insertion. Consequently a greater force is required to present the correct thread length for a perfect stitch. This can cause higher thread tension in the seam and induce puckering.

Conclusion:

Seam puckering is the most common but preventable defect in sewing and garment manufacturing. It causes for various reasons such as incorrect thread tension, fabric handling, stitch length, and fabric shrinkage etc. Proper machine settings, correct needle and thread selection, and fabric pre-treatment are key to minimizing puckering and ensuring smooth, high-quality seams.

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

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