Textile finishing includes all the mechanical and chemical processes applied to enhance the usability of textiles, except for those related directly to colouring. Finishing aims to make the fabric more appealing, functional, and ready for end use. The processes can range from preparatory treatments like bleaching before dyeing to treatments that improve appearance (like glazing), adjust texture (like sizing), or enhance performance (like preshrinking). Freshly produced fabric, often called "grey goods" or "greige," tends to be dirty, coarse, and unappealing, requiring significant finishing to transform into a desirable product.

Basic Methods of Textile Finishing

Historically, textile finishing involved simple, manual processes perfected by craftsmen, especially in England and Scotland. Modern textile finishing has evolved significantly thanks to extensive research and technological innovation. Let’s explore some of the key methods.

Preparatory Treatments

Before any major finishing process, certain preparatory treatments are essential to remove impurities and manufacturing residues, making the fabric suitable for further enhancement. These preparatory treatments include:

• Burling and Mending: After initial inspection, defects like burrs, loose threads, holes, and tears are corrected by hand. This process ensures that the fabric is free of flaws before entering further finishing stages.
• Scouring: This step cleanses grey goods, removing dirt, oils, and other residues from fibre production. It ensures that the fabric is clean and ready for subsequent processes.
• Bleaching: Bleaching removes natural colours (like linen’s tan hue) to achieve a uniform white base or prepare the fabric for dyeing. Depending on fibre composition, bleaching is done using either oxidation (via oxygen) or reduction (via hydrogenation). For instance, cotton is typically bleached using alkaline hydrogen peroxide, while wool requires acidic or mildly alkaline oxidizers.

Mechanical and Chemical Finishing Processes

Once preparatory treatments are complete, fabrics undergo various mechanical and chemical processes to enhance their appearance, texture, and functionality.

Enhancing Appearance

• Mercerization: Applied to cotton and some cotton blends, this process increases lustre, strength, and dye affinity by immersing the fabric in a caustic soda solution and then neutralizing it with acid. Mercerization causes a permanent swelling of the fibre, making it more attractive and vibrant.
• Napping and Shearing: Napping raises a velvety surface on fabrics like woollens, cotton, and spun rayons, adding warmth and a soft texture. Shearing trims this raised surface to uniform height, refining the texture and creating specific patterns or designs.
• Brushing: This process uses bristle rollers to remove loose threads and enhance surface smoothness. It also raises a nap, providing a softer touch, especially in knits and woven fabrics.
• Singeing: Also known as gassing, this process involves burning off loose fibres to create a smooth, even surface. It is a crucial step for yarns and fabrics, reducing fuzziness and improving the final look.
• Calendering: A final process that involves passing the fabric between heated rollers to create a smooth, glossy surface. Variants like moiréing, embossing, and glazing add decorative effects, such as wavy patterns, raised designs, or shiny surfaces.

Improving Tactile Qualities

• Sizing: This process involves applying compounds like starch, gelatin, or clay to fabrics, forming a film around fibres to add weight, crispness, and lustre. However, most sizing agents are temporary and may wear off after washing.
• Softening: Various agents, such as dextrin or glycerin, are applied to make fabrics softer. Softening treatments can also increase fabric absorbency.

Enhancing Performance

• Shrinkage Control: Compressive shrinkage, resin treatment, and heat-setting methods control fabric shrinkage. Compressive shrinkage involves dampening and relaxing the fabric under pressure, making it smoother and more durable. Resins and heat-setting help stabilize synthetic fibres, such as polyester and nylon, to minimize shrinkage.
• Durable Press: This technique imparts shape retention, crease resistance, and wrinkle resistance, allowing fabrics to maintain their appearance after washing and drying. Durable press methods can be either procured (before garment construction) or postcards (after garment construction).
• Waterproofing and Water Repellence: These treatments close fabric pores to make fabrics impervious to water or resistant to water penetration. Waterproofing is used for raincoats, while water repellence allows the fabric to remain breathable while shedding water.
• Flame Resistance: Fabrics can be treated with flameproof or fire-resistant finishes, enabling them to withstand exposure to heat or flames. These finishes vary based on the type of fabric and desired fire protection level.

Conclusion

Textile finishing transforms raw fabrics into consumer-ready products by improving their appearance, texture, and performance. With advancements in technology and chemical formulations, these processes continue to evolve, meeting the diverse needs of the textile industry and end consumers. From making fabrics smoother, softer, and more colourful to enhancing their durability and functional properties, finishing remains a crucial step in textile manufacturing.