Denim and Its Finishing Process
Denim and Jeans were created first for gold miners during the California Gold Rush. Dramatic changes have occurred in the function and design of denim garments since then. The evolution of the jeans’ market led to the development of some unique and creative methods for the processing of denim garments. Originally, denim and jeans were marketed and sold as workwear with primary emphasis on their durability and practicality. But when denim garments were discovered and appreciated by consumers as general casual wear, they became fashionable and new techniques were developed to enhance denim garments and make them more unique. The first generation of indigo jeans was stiff and uncomfortable. The second generation jeans incorporated pre-washing by the manufacturer.
Now denim is one of the most fashionable, and widely-used fabrics. It has become very popular within the area of fabric appearance, being modified to appeal to varied fashion trends and demands. Originally denim is a stiff fabric with an unpleasant dark blue color. The blue colored indigo denim changes the color and fades during wearing and after the washing treatments. Different looks and varying hues can be achieved on the same raw denim fabric by applying different dry and wet processes.
Denim becomes most popular for its special finishes. Special final finishing can be applied to enhance the hand and functionality of the denim garments. Denim finishing is an important textile operation for adding value to denim/jeans fabrics and making them attractive to younger customers, particularly by equipping them with a faded or worn fashion look.
You may also like: What is Denim | Different Types of Denim
Numerous operations exist in the denim industry to accomplish such a need, including sanding, sandblasting, sand washing, snow washing, stone washing with enzymes, prewashing, brushing, rinsing and bleaching. During denim processing, a part of the surface color is removed by pumice stones. This process can also be done in the presence of a bleaching agent varying in concentration and added to a fixed amount of pumice stone. Emerging waterless or less water–based technologies, such as laser, plasma, ozone and sandblasting, have also been explored for denim washing from the point of sustainability, and have produced excellent fabric handle. Laser treatment has been found to be a useful tool for good color fading of denim fabric with proper evenness, and for faster and accurate reproduction of the fabric look by controlling the laser process parameters. The laser action on colored denim is mainly an interaction with indigo dyes by the thermal effect. The process has three steps: (1) the generation of a computerized map of the fabric area that will be irradiated with different frequencies; (2) control of the laser system, scanning system and conveyor system; and (3) a laser-fading process. The color fading effect is not only affected by the laser power density but depends considerably on the laser resolution and pixel time.
Similar to the laser treatment, the plasma technology can be used to replace conventional stone washing or enzymatic bio-stoning processes that are used to impart the popular ‘worn look’ to the denim. Mostly, oxygen, argon and water vapour plasma generated at an atmospheric to a low-pressure condition has been used for colour removal of the denim fabric. Plasma can etch the surface of the indigo-dyed warp yarn besides oxidizing the dye molecules. The extent of etching was found to be more in the oxygen plasma– treated denim fabric than the water vapour plasma-treated sample. On the other hand, although the ozone finishing of denim does not eliminate the use of water completely, it could noticeably reduce the consumption of water, energy, chemicals, enzymes and stones. The rate of fading of indigo dye depends on the portion of the dye in the fiber and its solubility, and diffusion of ozone within the fiber. Sandblasting is a modern technique applied to the specific portions of the indigo-dyed denim apparel using special types of sands that do not cause problems associated with stone washing. The sandblast fading process is popular in the industry for achieving a worn vintage effect in denim fabric. In this article I will discuss some important techniques of denim fabric finishing.
You may also like: Process Flow Chart of Denim Manufacturing
Some Important Finishing Process of Denim Fabric:
Dry mechanical/physical finishing:
Different mechanical and physical processes are also available in the industry to provide an aesthetic and attractive look to the denim fabric. One such type of finishing is done on the pocket edges and bottom hems of denim fabric by rubbing it against the abrasive surface or stone. The distinctive effect of the denim fabric is achieved by using a swift tag machine with a plastic tag attached to the fabric to ensure a high color contrast effect on the denim fabric. Control warp removal and creating holes on both the warp and the weft of the denim fabric also provide a vintage worn look. The tie effect of the denim fabric has been achieved by transferring the irregularly dyed garment to the denim garment by a process similar to stone washing. It gives an attractive abraded effect to certain areas of the fabric. Permanent creases in the specific area, such as the pocket and hems of the denim fabric, also create worn and attractive looks.
Leather and wax finishing:
Generally, leather and wax finish form a thin layer on the denim surface and thus change the surface attributes of the treated fabric. Leather finishing of a denim garment is performed by using 660 g of anionic acrylic solution, 20 g of a cross-linking agent, 283 g of water and 37 g of a concentrated black pigment. This finish formulation is added to the denim fabric with 55.5% pickup. Subsequently, the treated fabric is dried and cured at 150°C for 5 min. Such a finish is simple to apply but provides a fast surface treatment for specific effects, in which short and dense fibers give a ‘peach skin’ effect. The leather finish can be applied either on a small area or on the whole denim surface. On the other hand, the wax finish provides a smooth, oily and greasy touch to the treated denim. The application of a special binder and chemicals provides an elastic, soft and silicone-like film on the treated area. The wax finishing of denim fabric has been carried out using 200 g of cationic polysiloxane emulsion, 700 g of polyurethane binder, 20g of a cross-linking agent and 80 g of black pigment with an appropriate quantity of water. The denim fabric was treated with this mentioned formulation with 49.9% pickup, followed by drying and curing at an adequate temperature for a sufficient time.
Soft resin finishing:
A special resin finishing is used to impart an authentic three-dimensional permanent crease that is resistant to wear and washing. Resin can also be applied by spraying it directly onto the denim fabric surface, and creases can be formed using binder clips or aluminium pipes, before or after spraying the resin. In addition, denim fabric has been treated with a mixed formulation of 200 g/L glyoxal resin, 100 g/L acrylate polymer and 20 g/L catalyst for the synthetic resin. The wrinkles were formed on the denim fabric by a flexible aluminium table, followed by drying and curing.
This particular treatment of denim fabric was carried out using an anionic aqueous solution of polysaccharide. It was applied to the denim fabric with 20.5%, followed by drying at 80°C. Then, the fabric was cracked and blown using compressed air. The broken places of the denim fabric were treated with a permanganate (5%) solution and left for 10 min. Thereafter, the sample was neutralized and treated with a nonionic softener, centrifuged and air-dried.
In this finishing process, denim fabric was treated with a mixed formulation of 100 g/L nonionic silicon emulsion and 5 g/L permanganate solution for 30 min at 30°C, maintaining a material to liquor ratio of 1:15. Thereafter, the sample was washed for 20 min at 60°C with a reducing agent and a softened, followed by centrifuging and air-drying.
Dirty effect finishing:
A few pigment-based dyes, such as Diresal Orange RDT or Diresal Brown RDT have been used to achieve a dirty effect on the denim fabric. Black pigment dyes have been used to impart a deep shade to the denim fabric. A pigment dye solution can be applied to the fabric by spraying it in a controlled manner. The treated fabric will look careless and fashionably dirty after the treatment.
You may also like: Dry Process for Denim Wash: Different Types and Techniques
Ice wash effect finishing:
In this particular finishing, the stones act as vehicles to deposit chemicals on the garments so as to strip the indigo color from the surface of the denim fabric. The surface chemical deposition will remove the color from the outer surface of the garment and deliver an attractive elegant, frosted appearance. Indigo and sulphur-dyed denim fabrics are normally applied for the ice wash effect.
Resin is used by the denim industry to create a unique and vintage look, e.g., the crinkle effect that can add value to denim garments and improve its value in the market. In 1980s, resin was used to provide nonpress, iron-free cotton trousers; now it is used on denims to create wrinkles and creases to impart a natural vintage look. The fabric gets a natural color that stays after multiple home washing. A wrinkle, also known as a rhytide, is a fold, ridge or crease in the cloth/garments that could induce a vintage and aged look in the fabric.
Antimicrobial and UV protective finishing:
The functional finishing process of denim garments using two natural oils: sweet citrus and rose oils. The 2/1 right hand twill was made from 100% cotton, cotton/polyester, 100% tencel and tencel/polyester blended fibers. These oils were applied by the exhaust method and the samples were tested for functional properties such as antimicrobial, antifungal and UV protection. From the antimicrobial test, it was inferred that the cotton/polyester and tencel/polyester denim fabrics inhibited the growth of the bacteria greatly more than was done by the pure cotton or tencel fabrics. The finished cotton and tencel/polyester denim fabrics completely inhibited the growth of fungi. As far as UV protection is concerned, the percentage of UV protection factor is excellent in the case of cotton (97.5%) and tencel/polyester (97.9%), followed by cotton/polyester (96.5%) and tencel (94.7%) denim fabrics.
You may also like: Antimicrobial Finishes of Cotton Fabric with Aloe Barbadensis
Special finishing process of denim results in attractive and respectable patterns as important design elements. The results of breaking force and spectral values indicate notable differences between special treatments. Acceptable special effects, according to technological indicators, can be obtained by the strato, leather, and wax finishes. Resin and the spider finish affect fabric weight and reduce its strength and usability in garments. Therefore, these special effects could be applied only as effective parts or segments of a garment.
- Sustainability in Denim. Editors: Subramanian Muthu
- Denim : Manufacture, Finishing and Applications. Edited by Roshan Paul
- Handbook of Value Addition Processes for Fabrics by B. Purushothama
- Influence of special finishes on denim properties by Dekanic T, Punic T, Soljacic I.
You may also like:
- Denim Jeans Production Process
- What is Denim | Different Types of Denim
- Process Flow Chart of Denim Manufacturing
- Denim Fabric: Types and Manufacturing Process
- Latest Dry Washing Techniques in Denim Garments
- Improving Comfort Properties of Denim Fabric through Washing Treatment
- Effect of Random Wash on Denim Fabrics by Using Different Techniques
- Textile Recycling and Uses of Recycled Denim
- Woven and Knitted Denim Manufacturing and Limitations of Woven Denim
- Dry Process for Denim Wash: Different Types and Techniques
- Denim Wet Processing: Importance of Blanket Wash
- Bleach Wash of Woven Denim: Analysis of before & after Wash Properties
- Cost Reduction in Dyeing of Denim Garments by Using Natural Indigo Dyes
- Performance Analysis of Denim Garments by Bleach Wash
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.