Safety Stitch

Definition and Overview

Safety stitching is a sewing method that generally combines a chain stitch for seaming with an overlock that wraps the edge of the seam allowance. Because seam joining and edge finishing can be done in one process, it is used for products that require both strength and production efficiency.

It is sometimes called a 5-thread lockstitch, but the name may vary by factory or specification sheet. When placing an order, do not judge by the name alone; confirm the seam position, how the seam allowance is finished, and the number of threads used from the specification drawing.

Role in Product Construction

In the sewing process after cutting, safety stitching is used for areas that require sufficient seam strength while preventing fraying of the seam allowance, such as side seams of the body, inseams, and underarms. It is a specification commonly seen in cut-and-sew items and workwear.

Compared with a method that finishes the edge in a separate process after sewing, it is characterized by making it easier to combine processes. On the other hand, it differs in appearance and process from specifications that press the seam allowance open or that press it to one side and add a topstitch on the outside.

How to Proceed and Practical Points

In planning and pattern making, align the seam allowance width and the position where the stitch will run in advance. On sharply curved areas, intersections where layers overlap, and fabrics with high stretch, the finished result changes depending on the seam allowance width and the differential feed setting.

In the specification sheet, clearly state the parts where safety stitching is to be used, the direction in which the seam allowance is pressed, the thread color, and the treatment at the start and end of stitching. Before mass production, confirm a sewing sample made with the actual fabric, and evaluate seam breakage when stretched, waviness in the stitches, and comfort against the skin.

• For knits and stretch fabrics, confirm conditions that allow sewing without pulling the fabric too much.
• For heavy fabrics, check the step at overlap areas in the seam allowance and thread breakage.
• When washing or garment dyeing is performed, also check puckering and seam shrinkage after processing.

Points to Note for Ordering and Quality

When placing an order with a sewing factory, simply writing "safety stitching" may not fully communicate the specification. It is important to attach a specification drawing showing the sewing location, front and back photos, and instructions for finishing the seam allowance, and to share samples if necessary.

During inspection, check for skipped stitches in the seaming and overlock sections, poor thread tension, insufficient encasing at the edge of the seam allowance, and seam opening. If the thread or needle is not suited to the fabric, it can lead to puckering, needle holes, or insufficient seam elasticity.

Differences from Similar Terms

Overlock is mainly a overedging stitch used to prevent fraying at the fabric edge and for sewing knit fabrics together. Safety stitching is characterized by adding the function of seaming to the overlock.

A lockstitch is the representative seaming stitch that uses upper and lower threads, and the edge of the seam allowance may be finished separately. A chain stitch is a general term for stitching that uses a looper, and in safety stitching, chain stitch may be used for the seaming part.

Frequently Asked Questions