Hot-water Soaking

Definition and Overview

Hot-water soaking is a pretreatment in which textile is immersed in hot water or passed through hot water to settle the fibers and woven or knitted structure. It is carried out to draw out the material’s residual shrinkage in advance and suppress dimensional changes after the product is made.

In particular, textile containing natural fibers may shrink, wrinkle, or change surface texture due to moisture and heat. Hot-water soaking is not a process that guarantees the finished result, but it is important as a step for understanding the behavior of the textile before full-scale production.

Parts Used and Role

Hot-water soaking is not applied to a specific part; it is usually done to the entire roll or the required yardage before cutting. It has the role of stabilizing the dimensions of the entire textile so that the body, sleeves, collar, pockets, and other parts can be cut under the same conditions.

It is considered for garments such as shirts, dresses, and pants, where post-wash dimensions easily affect wearing comfort. When using fusible interlining or tape, attention is needed not only to the outer fabric but also to any shrinkage difference after combining them.

Materials and Types

Cellulose-based fibers such as cotton and linen are materials for which shrinkage and changes in hand from hot-water soaking are easy to confirm. On the other hand, wool, silk, and rayon can undergo large changes in appearance and dimensions due to heat and moisture, so a suitable method for the material should be checked in advance.

Besides the method of immersing the textile in hot water, there is also a method of washing it in hot water and then drying it. Compared with water soaking, which uses only water, hot-water soaking also adds the effect of heat, so it is important to proceed only after checking the amount of shrinkage and the state of the dye on a test piece.

Main Applications

In home sewing, cotton and linen woven fabrics may be hot-water soaked before cutting to account for shrinkage from washing after completion. In apparel education for toile making and in prototypes using natural fibers, it is also done as a preliminary step to adjust the grain and dimensions of the textile.

Unlike finishing processes that add character to a sewn product after sewing, hot-water soaking is mainly intended to check shrinkage and pre-shrink the textile stage. Even for textile with a shrink-resistant finish, prior confirmation is carried out according to the application.

Selection, Handling, and Sewing Notes

Whether hot-water soaking is necessary is determined based on material composition, finishing, care label, and the expected washing method of the product. First, check the shrinkage rate in the length and width directions, color fading, wrinkles, skewing, and hand on a small test piece, and secure the necessary yardage before cutting.

After hot-water soaking, do not wring the textile strongly; align the grain and dry it flat or by an appropriate method. If you straighten the grain with an iron after drying and then cut, it becomes easier to reduce dimensional deviation at the time of cutting. For patterned fabric, also check for pattern distortion and color transfer.

• Textile that has already been finished may change in water repellency and hand through hot-water soaking.
• For products using fusible interlining, be careful of puckering caused by the difference in shrinkage between the outer fabric and the interfacing.
• In mass production, consider that the shrinkage rate may differ by roll or by lot.

Frequently Asked Questions

What is the difference between hot-water soaking and water soaking?

Water soaking is a pretreatment that mainly uses water to wet the textile and check shrinkage and the state of the dye. Hot-water soaking adds the effect of temperature, so shrinkage and changes in hand generally tend to appear more readily. Choose according to the material and the expected washing conditions.

Is hot-water soaking necessary for shrink-resistant textile?

Even for shrink-resistant finished textile, it cannot be uniformly judged that hot-water soaking is unnecessary. Dimensions and appearance may change depending on the type of finish, the material, and the product’s washing conditions. Before cutting, check the shrinkage rate and appearance on a test piece, and reflect the results in the sewing specifications or pattern as needed.

Can the textile be cut immediately after hot-water soaking?

After hot-water soaking, dry the textile thoroughly and straighten the grain before cutting. If you cut while moisture remains, hardware dimensions may shift due to dimensional changes after drying. For checks and stripes in particular, it is important to confirm the pattern alignment and skewing.