Shrinkage Rate
Shrinkage rate is a quality control indicator that shows, as a percentage, how much textile or a product has shrunk or stretched after washing, drying, heat treatment, or similar processing compared with its pre-treatment dimensions.
Definition and Overview
Shrinkage rate is an indicator used to check dimensional changes in textile caused by processes such as washing and drying. In general, it compares the length before and after processing, and is handled separately for warp and weft directions, or for knit fabrics, course and wale directions.
Not only shrinkage but also the phenomenon of dimensions increasing after processing is managed as dimensional change. The tendency of shrinkage rate varies depending on factors such as the textile composition, weave or knit structure, density, finishing process, dyeing method, and storage conditions.
Characteristics and Impact on Products
With textile that has a large shrinkage rate, garment length, body width, sleeve length, and other dimensions may change after sewing or after wear and washing, which can affect the intended fit. For patterns, differences in how the fabric shrinks may also affect the placement and appearance of pattern matching.
Textile containing natural fibers, as well as knit fabrics with a loose structure, tend to change in size more easily due to water absorption and mechanical force during washing. On the other hand, even synthetic fibers can change depending on heat and processing conditions, so they cannot be judged by material name alone.
How to Check and How to Handle in Production
When selecting textile, check the shrinkage rate shown by the supplier and the test conditions used. If the assumed product care method differs from the evaluation conditions, such as home laundering, commercial laundering, or use of a tumble dryer, the comparison results will also differ, so caution is needed.
Before mass production, perform washing tests and post-sewing checks with the actual textile to estimate the amount of shrinkage needed in the pattern. In particular, parts cut on the bias to the grain, and parts using interlining or accessories, should be checked for behavior that differs from a standalone textile test.
- Check warp and weft directions, or each direction of the knitted fabric, separately.
- Also consider variation within the bolt and between lots.
- If pre-washing or relaxing the grain before cutting, manage it under the same conditions as actual production.
- In addition to test results, also check twisting, waviness, and seam puckering after washing.
Selection and Handling Notes
The acceptable range for shrinkage rate varies depending on the garment application, size design, washing frequency, and care method assumed at the time of sale. For products intended for machine washing, such as shirts, cut-and-sew items, and bottoms, it is important to consider in advance how dimensional changes will affect wear comfort.
Even textile with shrink-proof finishing is not completely free of shrinkage. Follow the care label and manage water temperature, washing method, spin-drying, and drying method. High-temperature drying or excessive heat may cause shrinkage, distortion, or changes in texture depending on the textile.
Differences from Similar Terms
Shrinkage rate is a numerical value or indicator showing dimensional change as a percentage, while "shrinkage" is often used to refer to the phenomenon itself in which textile or products become smaller after washing or similar treatment. Shrinkage percentage is used with almost the same meaning as shrinkage rate, but the notation and calculation method should be checked with each trading partner.
Shrink-proof finishing is a treatment applied to suppress shrinkage caused by washing and similar processes. A low shrinkage rate does not mean that shrink-proof finishing has been applied. Also, spirality is a phenomenon in which the grain of knit or woven fabric twists after washing, and it is evaluated separately from simple dimensional shrinkage.
Frequently Asked Questions
In which directions should shrinkage rate be checked?
For woven fabrics, it is generally checked separately in the warp and weft directions. For knitted fabrics, it is necessary to check by direction according to the structure, such as course and wale directions. Because dimensional change differs by direction, judgments should be reflected in the corresponding parts of the product, such as garment length, body width, and sleeve width.
Can the textile shrinkage rate be added directly to the pattern?
Simply adding the test value uniformly may not be sufficient. The finished result changes depending on the cutting direction, the use of interlining or accessories, stretching or shrinkage caused by sewing, and whether the product is washed. Before mass production, wash sewn samples under assumed conditions and adjust after confirming the actual dimensions.
If the textile has shrink-proof finishing, is shrinkage rate confirmation unnecessary?
No, it is still necessary. Shrink-proof finishing is a treatment to suppress dimensional change, but changes may still occur depending on the material, structure, washing conditions, and drying conditions. It is important to check the stated test conditions and conduct advance testing according to the washing and drying methods assumed for the product.
