Different Types of Denim Dry Process
Originally denim is a strong, durable fabric constructed in a twill weave with an unpleasant dark blue color 100% cotton fabric. Different processing techniques are applied to change the colour, hand and feel of denim jeans and garments. Nowadays, these garments are processed to have a desirable worn out or vintage look as well as a soft handle, by applying combinations of different treatments. In general, these treatments can be classified as dry process and wet process. In this article I will discuss about different denim dry process techniques.
Different Dry Process of Denim Fabric:
Different denim dry process can be applied in different combinations to obtain the desired effect and color. Generally denim dry process are applied before denim wet process and it changes the visual appearance by mechanical abrasion without altering the construction and properties. The denim garment gets a nice look after dry process and also it adds value to the product. Fashionable denim garments are produced by the dry process.
There are both mechanical and chemical dry processes. Denim dry process are scraping, grinding, rupture (manual and machine damage), sanding, brushing, tagging, laser fading, resin, iron creases, flat press and sand blasting. The principle of the mechanical processes is to abrade or tear the products by using different abrasive equipments or knives in order to give the jeans a worn out effect, abraded look or used look. A mechanical damaging process is applied to the denim garments before permanganate spraying. After wet processes, these damages to the garments will increase.
Sanding:
The aim of sanding is to remove locally the indigo dyestuff from specific parts of the garment by using metal emeries or sandpapers of different numbers ranging from 40 to 600 (from coarser to finer scraping), for different effects and for different fabric weights. The sandpaper abrasion creates an obsolete image on the denim garment. On the garments, the abradable parts are the regions that are exposed to friction during daily life such as some parts of the knee, front pocket, hip pockets and hip regions.
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Scraping is done on inflated vertical or horizontal rubber mannequins or mandrels for better effect. The blown up legs (inflated rubber mannequins) are dressed with untreated jeans and the workers sand thighs and crotches or desired parts manually. Sandpapers that are used for sanding of denim products are used in different forms. Sandpaper wrapped around a soft sponge or on fine wooden stick material is used for different scraping purposes. Scraping must be equally applied on both legs of the jeans. Manual scraping process is shown in Figure-2. Diamond paper, glass paper and different grades of sandpaper create different colour contrasts on the jeans, increasing the attractiveness of the final product.
Sand blasting:
The sand blasting technique is based on blasting an abrasive material in granular, powdered or other form through a nozzle at very high speed and pressure onto specific areas of the garment surface to give the desired abraded look. A straighter surface and less effect can be obtained with the sand blasting process than with the sanding process, and sand blasting can be done in less time. For this reason, it is more advantageous in terms of costs. However, silicon grains that are located in the sand can cause silicosis disease. The sand blasting process is now prohibited in most countries because of its negative effect on human health.
Brushing:
A variety of effects can be achieved by using different types of brushes. Carbonium brushing is used to give a shiny effect on the garment surface. Several other types of brushing equipments are also used to give different effects on the garments.
Grinding:
Grinding, also called destroyed effect, is a method to tear the pocket edges, bottom hem edges, fly and knees to obtain unique destructions on the garments by using different abrasive methods. Depending on the desired effect, different knives and pen grinding tools are used to achieve a worn out effect. Figure-5 shows pen type stone tools, and Figure-6 shows grinding apparatus working with pressurised air. This apparatus is touched to the warp yarn for pilling or partial damage to the warp yarns.
Ripping, pilling and cuts are also created by using sharp edged tools, blades and knives. Generally, warp yarns are cut by the knife, and white weft is left to create a worn out look. To obtain holes, both of the yarns can also be destroyed, depending on the unique design of the jeans. The worn out effect at the bottom of the hems are obtained by a pen grinding apparatus.
Whiskers:
Whiskers are worn out lines generated by natural wearing around the hip to crotch area and at the back of knees, and they are formed in different strengths and shapes depending on the design of the garment. A specific shape or design is drawn with the help of a sharp edge of sandpaper manually or by using moulds. To obtain whiskers, the products dressed in mould and trace of mould under the product will be drawn with sandpaper to produce different types of whiskers. Furthermore, the whiskers can be drawn by laser, machine sanding, etc. Pattern shape and strength of whiskers must be similar in both legs of the jeans.
Tagging:
This process is done by tagging small plastic tag pins to hold small gathers of fabric around pockets, hips, seams and bottom hems to get strong contrast due to less exposure of the folded parts to mechanical rubbing and chemicals. Figure-8 shows the tag pins on the waistband and on the pocket of the jeans. After washing, the tags are snipped and colour contrasts and 3D effects are obtained in these areas. Variations are provided by using different lengths of tag pins. Using thick tags leaves large holes on the fabric surface after the washing processes, on the other hand, finer tags may break off during washing and the contrast appearance may not be achieved.
Laser fading:
Laser fading is another popular dry process in denim processing, and transfer of different images to denim garments is possible by using laser beams. After the intensity of the laser reaches a specific level, the lights are sent to denim surface to engrave the required pattern on the garment. The indigo dyestuff is burned and is removed during the washing process. It is possible to form whisker shapes, lines, different images and pictures on denim garments with the same quality for the whole batch. The intensity and duration of exposure determines the final effect on the fabric. The laser intensity must be chosen correctly not to damage the garments.
Resin applications:
Resin application is a process that is applied to denim garments to give dry and lustre appearance, to improve the rubbing fastness, to give 3D effects, to provide stiff and firm handle and to reduce pilling. Generally, resin application is the first step of dry processes. This process can be applied on denim garments in different ways including by spraying the resin solution or dipping the garment in resin solution. Different resin solutions give denim garments different effects. After resin application, jeans must be cured in ovens at the right temperatures and time to get the perfect result. Resin can be applied on jeans manually with a brush and with a sponge for partial applications. After resin application, the jeans are manually folded to obtain whole garment crush, partial crush or special streaky effects. The crushes or creases are formed on the high, hip and back knee or over the ankle to get 3D effects with different methods. After crushing or creasing, the jeans should be dried manually with a hot press and then must be cured in an oven at right temperature.
Aluminium flex pipes are widely used for crushing and creasing jeans legs. After placing these flex pipes inside the legs, operators can manually form different creases on the jeans. Then the creased jeans are cured for permanent creasing effects. Figure-10 shows the creases on the back of legs and over the ankle of jeans. Other techniques use shaping presses or frames similar to a grill to form a 3D crease effect. Resin reduces the tearing strength of the material and must be tested before applying on different types and weights of the fabrics. Moreover, if the resin is applied to elastic denim products, the elasticity of the fabric may be damaged, and for this reason the fabrics must be tested before applying resin.
3D crush effects:
There is a big demand in the market for 3D crushed effects on jeans. There are various types of 3D making equipments such as wire crinklers, crushing machines, aluminium flex pipes, shaping presses and grill frames. These methods can be applied to jeans after resin application for permanent 3D effects. Nowadays resins are used not only to produce ironing free products but also to make permanent wrinkles and creases to look natural vintage during the use.
There are countless variations in denim garment processing techniques to achieve fading, excellent handle and unique look. The results obtained after dry process Figure-12 shows combinations of different dry processes on jeans.
You may also read: Different Wet Process of Denim Fabric
References:
Different Dry Process of Denim Fabric:
Different denim dry process can be applied in different combinations to obtain the desired effect and color. Generally denim dry process are applied before denim wet process and it changes the visual appearance by mechanical abrasion without altering the construction and properties. The denim garment gets a nice look after dry process and also it adds value to the product. Fashionable denim garments are produced by the dry process.
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| Figure-1: Different denim dry process |
Sanding:
You may also like: Sustainable Denim Processing Technologies
Scraping is done on inflated vertical or horizontal rubber mannequins or mandrels for better effect. The blown up legs (inflated rubber mannequins) are dressed with untreated jeans and the workers sand thighs and crotches or desired parts manually. Sandpapers that are used for sanding of denim products are used in different forms. Sandpaper wrapped around a soft sponge or on fine wooden stick material is used for different scraping purposes. Scraping must be equally applied on both legs of the jeans. Manual scraping process is shown in Figure-2. Diamond paper, glass paper and different grades of sandpaper create different colour contrasts on the jeans, increasing the attractiveness of the final product.
 |
| Figure-2: Manual scraping of jeans. |
The sand blasting technique is based on blasting an abrasive material in granular, powdered or other form through a nozzle at very high speed and pressure onto specific areas of the garment surface to give the desired abraded look. A straighter surface and less effect can be obtained with the sand blasting process than with the sanding process, and sand blasting can be done in less time. For this reason, it is more advantageous in terms of costs. However, silicon grains that are located in the sand can cause silicosis disease. The sand blasting process is now prohibited in most countries because of its negative effect on human health.
 |
| Figure-3: Sand blasting of denim |
A variety of effects can be achieved by using different types of brushes. Carbonium brushing is used to give a shiny effect on the garment surface. Several other types of brushing equipments are also used to give different effects on the garments.
 |
| Figure-4: Brushing process of denim |
Grinding, also called destroyed effect, is a method to tear the pocket edges, bottom hem edges, fly and knees to obtain unique destructions on the garments by using different abrasive methods. Depending on the desired effect, different knives and pen grinding tools are used to achieve a worn out effect. Figure-5 shows pen type stone tools, and Figure-6 shows grinding apparatus working with pressurised air. This apparatus is touched to the warp yarn for pilling or partial damage to the warp yarns.
 |
| Figure-5: Pen type stone tools for denim grinding |
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| Figure-6: Grinding apparatus working with pressurised air. |
Whiskers are worn out lines generated by natural wearing around the hip to crotch area and at the back of knees, and they are formed in different strengths and shapes depending on the design of the garment. A specific shape or design is drawn with the help of a sharp edge of sandpaper manually or by using moulds. To obtain whiskers, the products dressed in mould and trace of mould under the product will be drawn with sandpaper to produce different types of whiskers. Furthermore, the whiskers can be drawn by laser, machine sanding, etc. Pattern shape and strength of whiskers must be similar in both legs of the jeans.
 |
| Figure-7: Whisker effect on jeans |
This process is done by tagging small plastic tag pins to hold small gathers of fabric around pockets, hips, seams and bottom hems to get strong contrast due to less exposure of the folded parts to mechanical rubbing and chemicals. Figure-8 shows the tag pins on the waistband and on the pocket of the jeans. After washing, the tags are snipped and colour contrasts and 3D effects are obtained in these areas. Variations are provided by using different lengths of tag pins. Using thick tags leaves large holes on the fabric surface after the washing processes, on the other hand, finer tags may break off during washing and the contrast appearance may not be achieved.
 |
| Figure-8: Tag pins on waistband and pocket of jeans |
Laser fading is another popular dry process in denim processing, and transfer of different images to denim garments is possible by using laser beams. After the intensity of the laser reaches a specific level, the lights are sent to denim surface to engrave the required pattern on the garment. The indigo dyestuff is burned and is removed during the washing process. It is possible to form whisker shapes, lines, different images and pictures on denim garments with the same quality for the whole batch. The intensity and duration of exposure determines the final effect on the fabric. The laser intensity must be chosen correctly not to damage the garments.
 |
| Figure-9: Laser fading of denim |
Resin application is a process that is applied to denim garments to give dry and lustre appearance, to improve the rubbing fastness, to give 3D effects, to provide stiff and firm handle and to reduce pilling. Generally, resin application is the first step of dry processes. This process can be applied on denim garments in different ways including by spraying the resin solution or dipping the garment in resin solution. Different resin solutions give denim garments different effects. After resin application, jeans must be cured in ovens at the right temperatures and time to get the perfect result. Resin can be applied on jeans manually with a brush and with a sponge for partial applications. After resin application, the jeans are manually folded to obtain whole garment crush, partial crush or special streaky effects. The crushes or creases are formed on the high, hip and back knee or over the ankle to get 3D effects with different methods. After crushing or creasing, the jeans should be dried manually with a hot press and then must be cured in an oven at right temperature.
Aluminium flex pipes are widely used for crushing and creasing jeans legs. After placing these flex pipes inside the legs, operators can manually form different creases on the jeans. Then the creased jeans are cured for permanent creasing effects. Figure-10 shows the creases on the back of legs and over the ankle of jeans. Other techniques use shaping presses or frames similar to a grill to form a 3D crease effect. Resin reduces the tearing strength of the material and must be tested before applying on different types and weights of the fabrics. Moreover, if the resin is applied to elastic denim products, the elasticity of the fabric may be damaged, and for this reason the fabrics must be tested before applying resin.
 |
| Figure-10: Creases on back of legs and over ankle of jeans |
There is a big demand in the market for 3D crushed effects on jeans. There are various types of 3D making equipments such as wire crinklers, crushing machines, aluminium flex pipes, shaping presses and grill frames. These methods can be applied to jeans after resin application for permanent 3D effects. Nowadays resins are used not only to produce ironing free products but also to make permanent wrinkles and creases to look natural vintage during the use.
 |
| Figure-11: 3D crushed effects on jeans |
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| Figure-12: Combinations of different dry processes on jeans. |
References:
- Denim: Manufacture, Finishing and Applications. Edited by Roshan Paul
- Sustainability in Denim. Editors: Subramanian Muthu
- http://textilelearner.blogspot.com/2013/12/different-types-of-dry-process-for.html
- http://textilelearner.blogspot.com/2018/09/dry-washing-techniques-denim-jeans.html
