Desizing

Definition and Overview

Desizing is the process of removing the sizing agent applied to warp yarns to prevent fuzzing and yarn breakage during weaving. It is often carried out before greige fabric proceeds to dyeing and finishing, and methods such as washing, enzymes, and chemicals are used depending on the type of sizing agent and the fiber.

In apparel, it generally refers to pretreatment for woven fabrics, but in traditional Japanese fabrics and similar materials, it is also used to mean removing sizing as part of the finishing process, alongside hot-water shrinking. It is important to confirm the item and processing purpose.

Impact on Hand and Function

Once the sizing agent is removed, the textile more readily absorbs water and dye, making it easier to stabilize subsequent processes such as scouring, bleaching, and dyeing. Excess residual sizing can cause uneven dyeing or processing irregularities, so uniform removal is required.

After desizing, the stiffness and firmness immediately after weaving are reduced, making the textile’s natural softness, drape, and surface texture more likely to appear. However, the final hand is determined by the entire process flow, including scouring, softening, and resin finishing.

Main Applications and Targets

For woven fabrics such as cotton and linen, it is carried out as pretreatment before dyeing, printing, or bleaching. It is a process involved in fabric preparation for a wide range of products that use woven fabrics, including shirts, blouses, pants, dresses, workwear, and bedding items.

Desizing is not a process that gives a specific seasonal characteristic. It can apply to everything from lightweight to heavyweight fabrics, but whether it is performed and which method is used depend on the fiber type, weave density, sizing agent used, and the details of the subsequent processing.

Selection and Handling Notes

When selecting fabric, check not only whether it has been desized, but also the processing details including scouring, dyeing, and shrink-proofing, as well as the finished width, fabric weight, and shrinkage rate. For fabric that is close to unprocessed, sizing may wash out during laundering or steaming, changing the hand and dimensions.

Before mass production, perform laundering tests and sewing tests within the roll and between lots to confirm shrinkage, skew, and puckering. If pattern, interfacing, and sewing conditions are set based on stiffness, seam distortion and changes in shape may become noticeable after washing.

• Whether home laundering is allowed depends on the fabric and the care label of the final product.
• Before cutting, relax the roll and, if necessary, hot-water treat it to confirm dimensional change.
• If the product requires a firm hand, confirm the finishing conditions after desizing as well.

Differences from Similar Terms

Scouring is the process of removing oils, waxes, and dirt contained in the fiber to improve absorbency and dyeability. Desizing mainly targets the sizing agent used for weaving, and the substances removed and the main purpose differ from scouring. The two processes may be carried out in sequence.

Prepared for dyeing (PFD) and bleaching are processes that whiten fabric after desizing and scouring, bringing it closer to a state suitable for dyeing and printing. Hot-water treatment is a process in which fabric is run through hot water or water before cutting to understand and stabilize shrinkage and changes in hand, and its purpose in product making is different.

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