Differences Between Preshrunk, Washed, and Sandwashed Silk Fabrics

                     Differences Between Preshrunk, Washed, and Sandwashed Silk Fabrics

• What is Preshrinking?
• Preshrinking is a process that uses physical methods to reduce fabric shrinkage after soaking, also known as mechanical preshrinking. It primarily controls the warp (length) shrinkage of the fabric. Before preshrinking, silk fabric can have warp shrinkage rates ranging from 5% to 15%. After preshrinking, the warp shrinkage rate is usually required to meet national standards of 3% or U.S. standards of 1%. Due to differences in drying methods, the U.S. standard of 1% is roughly equivalent to 3% under national standards.
• Common silk fabrics like crepe de chine, stretch satin, habotai, chiffon, and organza typically have shrinkage rates around 5%, with minimal noticeable shrinkage after washing. Therefore, if the product does not have strict shrinkage requirements, this process can often be skipped. However, silk double crepe, georgette, and chiffon fabrics have shrinkage rates over 10%, and preshrinking is necessary before cutting to prevent shrinkage in the final garment. Some silk fabrics like silk muslin can have shrinkage rates exceeding 25%.
• What is Washing?
• Washing involves adding softeners or detergents to water and soaking the fabric. Depending on the soaking time and amount of softener, washing can be classified as light wash, normal wash, or heavy wash. The result is a fabric that becomes very soft and has a more pronounced texture, giving the illusion of increased thickness.
• After washing, the fabric’s sheen may become slightly duller, resulting in a more subdued and sophisticated appearance.
• What is Sandwashing?
• Sandwashing is similar to washing but uses different additives, typically alkaline or oxidizing agents, along with some softeners. The purpose of the alkaline agents is to break down the surface fibers of the fabric, making it softer. The fabric's surface will develop a slight nap and a hazy appearance.
• Sandwashed fabrics become very soft, develop a nap, and give the impression of being thicker. However, this treatment makes the fabric more prone to tearing, so it is generally not recommended for thin fabrics. Sandwashed fabrics have a vintage look, which is popular among designers who favor retro styles.
• Summary
• Washing involves the addition of detergents or softeners, which results in fabrics that are softer and thicker in texture compared to preshrunk fabrics. Preshrunk fabrics feel fuller and more substantial but do not become softer; some, like silk georgette, might even feel stiffer. Washed fabrics not only feel fuller and thicker but also become softer and smoother, with a slightly duller sheen compared to their pre-washed state. Sandwashed fabrics are easily identifiable by their fine white nap when held up to the light.
• In summary, while both washing and preshrinking alter the fabric’s texture and feel, they achieve different results. Preshrunk fabrics remain more substantial but not necessarily softer, whereas washed fabrics are softer and smoother. Sandwashed fabrics, with their distinct vintage look and soft, napped surface, offer a unique aesthetic favored by many designers.
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