Flatseamer
Flatseamer is a sewing method that joins the edges of knit fabric by butting them together and stitching them so the seam lies flat, reducing bulk from overlapping seam allowances.
Contents6 sections
Definition and Overview
Flatseamer refers to a sewing specification in which the front and back of the joined section are finished relatively flat, or to the machine used for it. In general, it joins fabric edges while overcasting them with multiple needles and multiple threads, creating a structure in which seam allowances are less likely to overlap on the skin side.
Because it easily follows the movement of stretchy knit fabric and helps reduce the discomfort caused by seam thickness and steps, it is used for garments worn close to the skin and for sportswear.
Position in Product Construction
Flatseamer is a specification designated in the sewing process for joining cut parts. It is set at areas with frequent contact with the skin or a lot of movement, such as the side seams of the body, underarm seams, inseams, and shoulders. Depending on the fabric characteristics and design, it is used in place of standard joining specifications.
At the planning stage, decide whether the design will show the flat seam or whether it will be used on the inside for wearing comfort. Since the seam allowance design in the pattern may differ from standard overlock sewing, confirm the factory specification at an early stage.
Process and Specification Instructions
When placing an order, clearly specify the areas where flatseamer will be used, the appearance on the front and back, thread color, and how the fabric edges are aligned in the specification sheet and sewing sample. Even with the same name, there are differences among factories and equipment in seam width, number of needles, thread configuration, and how the fabric edges are overlapped.
Before mass production, test sew with the actual fabric and check the stretched state and the state after washing. In particular, with highly stretchable fabrics, thin fabrics, and slippery fabrics, differential feed and thread tension can easily affect the finish, so it is important to finalize the conditions with advance samples.
- Specify the sewing area and the front and back of the seam.
- Set the seam width, thread color, and allowable seam misalignment.
- Check skipped stitches, thread breakage, and seam opening under stretch.
- Check waviness, shrinkage, and feel against the skin after washing.
Ordering and Quality Considerations
Because flatseamer requires dedicated equipment and workmanship experience, confirm with the factory whether it can be handled, the fabric thickness it can accommodate, and the degree of curvature that can be sewn. On fine curves or sharp corners, the fabric edges may not align well, and the seam width and appearance may become unstable.
For quality inspection, check for variation in seam width, protruding fabric edges, seam misalignment, puckering, and skipped stitches. Also evaluate whether the seam pulls when worn and whether there is thread breakage or seam opening after stretching, in line with the product's usage conditions.
Differences from Similar Terms
Overlock is a representative sewing method that prevents fraying at fabric edges while joining pieces. Because seam allowances are often overlapped in processing, seam thickness and steps are more likely to appear than with flatseamer.
Coverstitch is a type of chain stitch mainly used for hemming, cuff finishing, elastic attachment, and similar applications. It often has parallel top-side stitches and looper thread on the underside, and its use and structure differ from flatseamer, which butt-joins two fabric edges to create a flat seam.
Frequently Asked Questions
Are flatseamer and flatlock the same?
In many cases, they are used in a similar sense as sewing specifications that create a flat seam. However, flatseamer may refer to the machine or process, while flatlock may be used as the name of the seam itself. When placing an order, it is necessary to confirm with a sewing sample.
What kinds of products are suitable for flatseamer?
It is suitable for cut-and-sew items, innerwear, sportswear, leggings, and similar products where you want to reduce seam steps. While it easily follows fabric stretch, for thick fabrics, stiff fabrics, or areas with many complex curves, confirm suitability and finish in advance.
What should be checked during flatseamer inspection?
Check the left and right seam widths, the butt-joined state of the fabric edges, seam misalignment, skipped stitches, thread breakage, and waviness. In addition, check by fitting and after washing whether the seam opens when the fabric is stretched in the specified direction and whether it presses strongly against the skin when worn.
