Seam Slippage
Seam slippage is a quality issue in which, when force is applied to a sewn area of woven fabric, the warp and weft threads shift around the seam and the opening widens.
Contents6 sections
Definition and Overview
Seam slippage is a phenomenon that occurs mainly at seams in woven fabrics. Even when the sewing thread has not broken, the yarns are pushed apart along the needle holes and seam line, causing the weave on the seam allowance side to shift and gaps to appear.
- Unlike fabric tearing, it is caused by the movement of the yarns.
- The mechanism differs from needle-hole damage, skipped stitches, and puckering during sewing.
Where It Occurs Easily and Its Effects
It tends to be a problem at seams that are subjected to pulling or friction during wear, such as sleeve attachments, armholes, sides, crotch seams, pocket openings, and vents. In linings, it may become noticeable due to friction against the outer fabric or interlining, or due to pulling when putting on or taking off the garment.
When seam slippage occurs, it not only spoils the appearance around the seam, but may also reduce seam durability and affect comfort because the seam allowance is not sufficiently secured.
Relationship to Materials and Structure
The likelihood of seam slippage is not determined only by the fiber type; it depends on the combination of weave structure, yarn thickness, yarn twist, density, finishing, thickness, and other factors. In particular, weaves with long floats or low-density, slippery woven fabrics may allow the yarns to move more easily.
Thin, slippery woven fabrics used for linings offer excellent ease of dressing, but depending on the area and sewing conditions, attention to seam slippage is necessary. Also check the seam behavior when the outer fabric, interlining, and lining are layered together.
Selection and Sewing Precautions
When selecting fabric, check not only the slipperiness with the outer fabric, stretch, and sheerness, but also whether the weave opens at locations where force is applied to the seam. For stretch outer fabrics, consider a lining that can follow the stretch, and avoid localized stress caused by differences in stretch between the outer fabric and lining.
In sewing, match the seam allowance width, seam position, needle and thread thickness, stitch density, and thread tension to the fabric. If necessary, consider reinforcement at stress points, redesigning the seam allowance, or using stay tape. Before mass production, it is important to sew samples using the actual specification and check them while applying tension.
- Do not make the seam allowance excessively narrow
- Avoid needles or threads that are too thick for the fabric
- Do not make stitch density or thread tension excessively high
- Test the specification including the outer fabric, lining, and interlining
Differences from Similar Terms
Shirring is a broader term for a condition in which yarns move and the weave becomes distorted or uneven, and seam slippage around seams may be treated as shirring. In practice, the two terms are sometimes used with similar meanings, so clarify and share the location of occurrence and its relationship to the seam.
Stretch refers to the elastic property of the fabric and is not seam slippage itself. However, if the stretch of the fabric and the stretch of the seam do not match, stress can concentrate on the seam and become one factor that makes seam slippage more noticeable.
Frequently Asked Questions
Are seam slippage and shirring the same thing?
Both relate to a condition in which yarns move and the weave opens or becomes distorted, but seam slippage generally refers to the phenomenon in which yarns shift and gaps form due to pulling, especially around seams. Shirring may be used as a broader expression that also includes areas other than seams.
Is it necessary to check for seam slippage in linings too?
Yes. Linings are often thin, slippery woven fabrics, and stress is applied at armholes, sides, vent hems, and around pockets. Including overlap with the outer fabric and friction during dressing, sew samples and check them in a condition close to the product specification.
Can seam slippage be prevented by making the seam allowance wider?
Securing a wider seam allowance is one countermeasure, but it cannot necessarily prevent the problem on its own. Fabric structure and density, needle and thread selection, stitch density, and the force applied to the sewing area are all related. It is important to consider the fabric selection, sewing conditions, and reinforcement methods as a whole.
