Mechanical Stretch

Definition and Overview

Mechanical stretch is stretch and recovery obtained by using yarn crimp, yarn arrangement, woven or knitted structure design, and finishing processes. In general, it differs from stretch materials that use polyurethane in combination to create stretch.

In woven fabrics in particular, there are many designs that stretch in the weft direction, but the direction and degree of stretch vary by material. Natural stretch is sometimes used as a sales term for this kind of modest stretchability.

Look and Function

Compared with stretch materials that have strong resilience, it is characterized by a natural stretch feel while still being able to achieve the firmness and appearance of woven fabric. Depending on the design, it can also contribute to suppleness, wrinkle resistance, and reduced tightness during movement.

However, stretch percentage and recovery rate cannot be judged from the name mechanical stretch alone. Since some materials do not stretch as much as polyurethane-blend materials, and some may retain stretch after repeated wear, confirmation according to the intended use is necessary.

Main Applications

It is used for garments where moderate ease of movement is needed while maintaining a neat appearance. Pants, jackets, skirts, dresses, shirts, light outerwear, and uniforms are the main applications.

It is found in a wide range of fabrics from lightweight to medium-weight, from lightweight materials for spring and summer to materials for year-round suits. Seasonality is determined not by whether it has mechanical stretch, but by the material, fabric weight, structure, and finish.

• When you want to improve range of motion around the knees and hips of pants
• When you want to add a natural wearing feel to jackets or suits
• When you want to give shirts or blouses moderate ease
• When you want both a neat appearance and ease of movement in uniforms and similar items

How to Choose and Handling Notes

At the planning stage, confirm the stretch direction, amount of stretch, and recovery in actual testing. In pattern making, adjust ease allowance based on the fabric’s stretch and recovery, and the finished result will be more stable if you also check bias-direction stretch and differences in stretch by area.

Before cutting, let the fabric relax by rolling it out, and if necessary, water test it or conduct a trial. During sewing, feed the fabric without pulling it to prevent seam shrinkage and puckering. Where stretch is needed in the seam itself, consider the seam specification and sewing thread selection.

Shrinkage, twisting, and residual stretch after washing vary depending on the material and processing conditions. Perform washing tests before mass production, confirm shrinkage rate and dimensional change, and reflect the results in care labeling and product dimension design.

Differences from Similar Terms

Stretch refers broadly to the property of fabric stretching and recovering. Mechanical stretch is a type of stretchability in which stretch is obtained through physical design such as yarn and structure, rather than mainly by blending elastic fibers.

Stretch with polyurethane blend generally makes it easier to achieve greater stretch and recovery, while mechanical stretch tends to simplify the material composition and preserve the original look of woven fabric. However, performance should be compared using the specifications of each individual fabric.

Frequently Asked Questions