What is Denim Washing?

The process of giving denim special washed/vintage looks and color effects after stitching it into jeans or other garments. Over the past few decades, different denim washing techniques have been developed and used on different materials to create a large variety of designs for trendy denim garments and jeans. Special color effects and washed/vintage looks are often achieved in denim garments. The hand feel of the washed goods is relatively superior, which makes them suitable for leisure wear. These effects are difficult to achieve through other processing techniques. The results obtained from denim washing represent a combined effect of color dissolution, destruction of the dye and mechanical abrasion, which sometimes causes the removal of surface fibers from the materials. Thus, surface dyed colors in denim garments are more easily washed down during the washing processes.

According to textile terms and definition, denim is defined as ‘Traditionally a 3/1 warp faced twill fabric made from yarn dyed warp and undyed weft yarn. Typical construction of the fabric is 32×19; 45× 54tex; 310g/m². More recently, other weaves have been used with lighter constructions. Jeans are defined as ‘A 2/1 or 3/1 warp faced twill fabric used chiefly for overalls or casual wear with a typical construction of 35× 24; 32×21tex cotton’. Although, denim and jeans refer to different things, they now mean the same thing in the market. Conventionally, warp yarn in denim fabric is dyed with indigo with a ring dyed effect.

Evolution of denim garment washing

Denim garments in the market are originally stiff and uncomfortable when first purchased because of the finishing system used for denim fabrics. After weaving, the heavily sized fabric is subjected to desizing and compressive shrinkage treatments. After the treatments, the softness of the denim fabric is seriously affected. In the past, many consumers used to take a newly purchased pair of jeans home and soften it by washing once or several times before the first wearing.

In the earliest evolution, the garments were laundered (prewashing) by the manufacturer before selling. These ‘prewashed’ denim garments had a slightly faded appearance and a softer hand that felt comfortable. These prewashed garments generated a trend of fashion and consumers were willing to pay the extra cost involved in this additional processing. As the popularity of prewashed garments grew, the idea of using abrasive stones to accelerate the color fading process was developed and ‘stone washing’ became the second step in the evolution. Pumice stones were included in the washing process or tumbled with the damp garments to wear down the stiffest portions, for example, belt areas, cuffs and pockets. The third development was the use of chlorine (e.g. sodium hypochlorite as a bleaching agent) in the washing process. A new and color lightened blue denim garments category was the result. With the use of chlorine bleaching, in 1987–1989, ‘ice washing’ was developed, in which the pumice stones were first presoaked in the bleaching agent and then tumbled with dry or slightly damp garments.

In the industry, ‘ice washing’ has alternative names such as ‘acid wash’, ‘snow wash’, ‘white wash’ and frosting, etc. The term ‘acid wash’ is a misleading term because mineral acids are not used for this process. Other than bleaching agent, the use of enzyme (cellulase) treatment to obtain the color fading effect like stone washing effect in denim garments has attracted considerable interest over the past several years. The primary attraction is to reduce or eliminate the need for stones or to reduce the time needed to obtain the desired abrasion effect. Moreover, using pumice stones to abrade denim garments is destructive to equipment. In addition, the pumice stones, after washing, get entrapped in pockets of denim garments which must be removed by hand, leading to increased labor and production cost. Also, stone particles and grit play havoc in the effluent. For these reasons, the use of cellulase was promoted with the promise of eliminating stone as the abrasive agent for achieving the ‘stone wash’ look.

However, because of the increased time and other considerations, the trend today is to use combinations of stone and cellulase to achieve the worn and faded look in denim garments. With the increasing awareness about and concern for environmental issues, such as large amounts of effluents produced and high consumption of water and energy, wet processes related to denim washing are considered as not environmentally friendly. To address the environmental concerns, dry finishing techniques such as plasma treatments have been introduced as an alternative to the conventional wet processing.

Washing as final process of denim garments

Washing can be considered as the final process in denim production and is the core of denim finishing. The washing of denim is directly related to the aesthetic, quality and value of denim garments. In processing, sizing and coloration form the base of color in denim garments. However, the washing process is the key to create the style in denim garments which is now becoming an art of creating fashion trends. The three-dimensional (3D) effect and worn look can be achieved through different types of finishing and washing processes. Under the influence of different chemicals, washing conditions and washing equipment used, different final effects can be achieved in denim garments. As a result, the washing of denim and jeans is aimed at:

• Preshrinking for good dimensional stability during selling and use.
• Removing sizing agent and unfixed dyes to remove contaminants added during the manufacturing process to generate ‘clean’ denim garments. Also, the washing can increase the surface luster and lightness of the fabric.
• Improving the hand feel through various finishing processes such as softening, stiffening or polishing to enhance the comfort of denim garments.
• Improving aesthetic properties through fading, bleaching or tinting processes. After these treatments, cloudy, frosted, wrinkle, grinded or peach skin effects are achieved which finally affect aesthetic properties.
• Improving the functional properties such as wrinkle free, anti-soil, water repellence, oil repellence or antistatic, etc.
• Improving the quality in cases of poor color yield, dimensional stability, color fastness or improper surface treatment.