Pre-degumming / Post-degumming
Pre-degumming and post-degumming are processing methods for silk fabrics that indicate whether the sericin in silk yarn is removed by degumming before weaving or after weaving.
Contents6 sections
Definition and Overview
Pre-degumming is a method in which silk yarn is degummed to remove sericin before dyeing the yarn or weaving. Post-degumming is a method in which the silk yarn is woven with the sericin left in place, and then degummed after it has become fabric. Degumming refers to the process of removing the sericin that covers the surface of silk.
Both are process-based distinctions used mainly for silk fabrics and are not names of weave structures. The actual hand and appearance also vary depending on yarn thickness, twist, weave density, dyeing, and finishing, so they are not determined uniformly by pre-degumming or post-degumming alone.
Hand and Appearance Characteristics
With pre-degumming, sericin is removed before weaving, so it tends to make it easier to bring out the yarn's natural softness and suppleness. On the other hand, degummed yarn is more slippery on the surface, so careful handling during weaving is needed depending on the material and process.
With post-degumming, sericin protects the yarn during weaving and helps keep the yarns together. When degumming is done after weaving, shrinkage and tightening of the structure may occur as the sericin is removed, and this may result in a relatively full and substantial texture.
Main Applications
Pre-degumming and post-degumming are considered for silk fabrics such as habutai, dechine, and chirimen, depending on the desired hand. They are used for items that make use of silk's luster and drape, such as blouses, dresses, scarves, traditional garments, linings, and dresses.
When a thin fabric with a soft look and light wearing comfort is important, the characteristics of pre-degumming are referenced. When designing with an emphasis on structure, body, and the change after degumming, the post-degumming process becomes an option.
Selection and Handling Notes
When selecting fabric, confirm not only whether it is pre-degummed or post-degummed, but also the fabric width after degumming, fabric weight, shrinkage rate, care label, and colorfastness. For post-degummed goods, it is important to use the standards in the state after the degumming process and to check for differences in hand and dimensions from the sample during mass production.
Silk is a material that is easily affected by moisture, friction, heat, and alkaline detergents. Whether home washing is possible should follow the product's care label, and during sewing, pay attention to needle marks, seam shrinkage, and puckering at the seams. Before cutting, if necessary, let the fabric relax and align the grain.
- Before mass production, perform a washing test or dry-cleaning test to confirm dimensional change.
- When using interlining or other accessory materials, verify in advance any shrinkage difference from the outer fabric and the bonding conditions.
- When ironing, use a pressing cloth and be careful of glazing or ring marks caused by excessive temperature or steam.
Differences from Similar Terms
Yarn dyed and piece dyed are terms that indicate when dyeing is done: either dyeing the yarn stage, or dyeing after the fabric has been woven. In contrast, pre-degumming and post-degumming indicate whether degumming to remove silk sericin is done before or after weaving.
Degumming is also used as a general term for pretreatment that removes oil and impurities, but pre-degumming and post-degumming are used especially when explaining the relationship between silk sericin and the weaving process.
Frequently Asked Questions
Which is more likely to shrink, pre-degumming or post-degumming?
Shinkage cannot be judged by the pre-degumming/post-degumming distinction alone. With post-degumming, the structure may tighten during degumming after weaving, so the finished fabric width and shrinkage rate should be confirmed. In addition, dimensional change due to washing or cleaning after the product is made must also be checked through testing.
Do pre-degumming and post-degumming mean the same as yarn dyed and piece dyed?
No, they do not mean the same thing. Yarn dyed and piece dyed indicate the timing of dyeing, whereas pre-degumming and post-degumming indicate the timing of degumming to remove silk sericin. There are cases where pre-degummed yarn is dyed and cases where post-degummed fabric is dyed, and the two are considered separately as different processes.
