What is Denim Fabric?
It is really commendable that denim has survived through all these years since its creation. Generally denim, a cotton woven fabric, may be the most considered article of style today. Denim fabric is a heavy cotton twill made of coarse yarns. A strong warp face cotton cloth used for overall, Jeans skirts, etc. Largely made in 3/1 twill weave. Generally warp yarn is dyed dark brown or indigo blue and crossed with white weft. “White back” denim, made with brown or blue warp and white filling. Denim is cut and sewn in an assortment of clothing types fit for all ages, seasons and events. Although conventional denim is still in use, many novel variants have been developed, driven by fashion, comfort and ease in production. Uses of denim are couch covers, upholstery, hangings, slip covers and dress materials. Generally four types of novel variants of denims are widely used such as generic denim, pseudo denim, stretch denim and reverse denim. In this article I will explain about reverse denim; manufacturing process, printing techniques and uses.
What is Reverse Denim?
Reverse denim is a novelty use of denim when it is turned inside out to give jeans a really different look. A reverse denim is one in which the warp yarns on the face of the fabric are not colored, whereas the background fill yarns are colored. This effect is achieved by blocking dye ability of the warp yarns unaffecting the fills. For this, the technique to be followed is application of a cross-linking finish to the raised warp yarns in the face of the fabric. Subsequent to the cross-linking treatment, the fabric is piece dyed to achieve the reverse denim appearance. Since dyeing is delayed until finishing, the fabric is a generic one and dyeing can be performed after the garment fabrication. The system is also amenable to produce fabrics with two color effects, if dye is included with the cross-linking finish treatment.
The advent of garment dyeing has in fact created opportunities to produce generic denims. The creation of the above finish effect, leading to reverse denim on dyeing, has thus a potential role to play. Interestingly, the face of a normal ring dyed indigo denim after extended wear, usage and laundering takes on the appearance of reverse denim, in that the raised portions of the warp yarns are relatively color free while the recessed part of these yarns remains dyed. Thus in the process a kind of reverse denim look is achieved. However reverse denim and worn out denim have subtle differences:
- In reverse denim, the raised warp yarns are selectively treated with cross-linking agents, and much of the face of the fabric is cross-linked thus giving a crisp look to the fabric with a smooth dry performance. However, worn out denim does not have this effect at all.
- Because the cross-linking treatment does not reach either the recessed filling yarns or the yarns on the back of the fabric, both of these areas become colored on piece dyeing of the fabric unlike a worn out one.
Sometimes reverse denim is also called waxed reverse denim. A very innovative take on the denim fabric was making a side of its water-resistant. In this case, the reverse side (inside) of the denim is waxed to provide water-resistance. This means the wax treatment is brushed or rubbed onto the reverse side of the denim, leaving the front side (relatively) unwaxed. Bags and most outdoor gear can be made out of waxed reverse denim.
Manufacturing Process of Reverse Denim:
The procedures utilized to produce mock or generic denims can also be employed for production of reverse denim. The major difference is that the chemical formulations are to be modified to lead to dye resistance rather than dye enhancement. Here, a cross-linking agent along with catalyst and auxiliaries may be applied first by a pad-dry-cure method. Then they may be dyed with reactive dyes by conventional dyeing procedures with alkaline fixation. As regards the chemical finish, the recipe may have DMDHEU, MgCl2·6H2O, glycolic acid and wetting agent. The application can be done by the loop transfer technique discussed in the pseudo denim section. Reverse denims made by such techniques have been found to give good durable press (DP) rating as well as the desired colored effect on subsequent dyeing.
A second approach for the production of reverse denims is a kiss-roll padding technique, as shown in Figure-2. In this operation, the resin finishing is carried to the face of the fabric with the add-on adjusted as per requirement. With the kiss-roll system, a liquid application as low as 10–20% can lead to an even distribution on substrate. After padding the fabric by this technique, it is dried and cured. On dyeing the cured fabric, the back side of this fabric is completely dyed, in contrast to regular denims.
Printing Process of Reverse Denim:
A third approach for producing reverse denims is by use of a printing technique for application of the resist-resin application using a clear screen with an acid dye as marker.
Printing using a Zimmer MDF print machine has been found suitable for producing reverse denims. Experimental work with varying recipes has been attempted in the past. A typical print paste formulation includes cross-linker, acid catalyst, thickener, wetting agent and a small amount of an acid dye. The catalyst used is based on 2-hydroxycarboxylic acid. The catalyst is for grafting on cellulose to help improve the resist characteristics of the printed areas. The fabric so printed is then dried and cured. The fabrics can then be dyed with the desired color to get a reverse denim effect.
Print applications for the two color effect:
A two color effect is possible by incorporating a reactive dye in the printing formulation containing cross-linker and acid catalyst. Once the finish is fixed, the resulting fabric or garment segment can be dyed with a second color under normal dyeing conditions. The areas of the fabric treated with the resin system and dye are resistant to the second dyeing, thus leading to a two color effect.
Uses of Reverse Denim:
Reverse denims are used in various purposes but specially used in backpack, weekender, dopp kit, and a tote. It is also used in cushion cover and hat. There is good reason denim’s the quintessential work wear fabric. The stuff is tough as nails, built to last for years even as you do you’re very best to destroy it. And considering the daily abuse it’s subjected to, that sort of durability is exactly what you want from your bag.
- Denim : Manufacture, Finishing and Applications Edited by Roshan Paul
- Sustainability in Denim. Editors: Subramanian Muthu
- Handbook on fabric manufacturing by B. Purushothama
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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.