Seam Slippage

Definition and Overview

Seam slippage is a phenomenon that mainly occurs at woven fabric seams. Even when the sewing thread has not broken, the woven threads are pushed apart along the needle holes or seam line, and the structure on the seam allowance side shifts, creating visible gaps.

• Unlike fabric tearing, it is caused by movement of the woven threads.
• The mechanism differs from damage caused by needle holes during sewing, skipped stitches, and puckering.

Areas Where It Occurs Easily and Its Effects

It is most likely to be a problem at seams subjected to pulling or friction during wear, such as sleeve attachment, armholes, side seams, crotch seams, pocket openings, and vents. In linings, it may become noticeable due to friction with the outer fabric or interlining, or due to pulling when putting on or taking off the garment.

When seam slippage occurs, it not only affects the appearance around the seam, but may also reduce seam allowance retention, affecting seam durability and wearing comfort.

Relationship to Material and Structure

The likelihood of seam slippage is determined not only by the type of fiber, but also by the combination of weave structure, yarn thickness, yarn twist, density, finish, thickness, and other factors. In particular, in structures where yarn floats are long or in woven fabrics with low density and a smooth surface, the woven threads may move more easily.

Thin, smooth woven fabrics used for linings offer excellent ease of putting on and taking off, but depending on the area and sewing conditions, attention to seam slippage may be necessary. The behavior of seams in the layered state of outer fabric, interlining, and lining should also be checked.

Selection and Sewing Precautions

When selecting fabric, check not only the slipperiness, stretch, and sheerness relative to the outer fabric, but also whether the fabric opens up at areas where force is applied to the seam. For stretch outer fabrics, consider a lining with the ability to follow stretch, and avoid localized stress caused by differences in stretch between the outer fabric and lining.

In sewing, match seam allowance width, seam position, needle and thread thickness, stitch density, and thread tension to the fabric. If necessary, consider reinforcement at high-stress areas, changes to seam allowance design, and the use of stay tape. Before mass production, it is important to make test seams using the actual specifications and check them under tension.

• Do not make the seam allowance excessively narrow
• Avoid needles or thread that are too thick for the fabric
• Do not make stitch density or thread tension excessively tight
• Test using specifications that include the outer fabric, lining, and interlining

Differences from Similar Terms

Weave distortion is a broad term for the condition in which woven threads move and the weave becomes distorted. Seam slippage may be treated as a type of weave distortion that occurs around a seam. In practice, the two terms are sometimes used in similar ways, so clarify and share the relationship between the location of occurrence and the seam.

Stretch refers to the elastic property of fabric and is not seam slippage itself. However, if the stretch of the fabric and the stretch of the seam do not match, stress may concentrate on the seam, which can be one reason seam slippage becomes noticeable.

Frequently Asked Questions

Do seam slippage and weave distortion mean the same thing?

Both relate to woven threads moving and creating openings or distortion, but seam slippage generally refers to the phenomenon in which woven threads shift due to pulling and create gaps, especially around a seam. Weave distortion may be used as a broader expression that includes areas other than seams.

Is it necessary to check seam slippage in linings as well?

Yes. Linings are often thin, smooth woven fabrics, and load is applied at areas such as armholes, side seams, hem vents, and around pockets. Including overlap with the outer fabric and friction during dressing, carry out test sewing and verification in a condition close to the product specifications.

Can seam slippage be prevented by making the seam allowance wider?

Securing seam allowance width is one countermeasure, but it does not always prevent the issue on its own. The fabric structure and density, the selection of needles and thread, stitch density, and the forces applied to the sewn area are all related. It is important to consider everything together, from fabric selection to sewing conditions and reinforcement methods.