| Garment dyeing, allowing a faster response by retailers to the market preferences, is gaining attention, so as the relevant dyes and chemicals, observes Ian Holme |
Garment dyeing allows a faster response to the consumer purchasing preferences |
Over the last decade preferences in apparel have favoured casual wear and leisure wear because of the more relaxed and less formal approach to modern lifestyles. Casual wear and leisure wear garment sales are very dependent upon colour and fashion and retailers have developed good lines of communication with garment dyeing companies because garment dyeing can provide the rapid response to the market demands.
Bar code retailing and electronic point of sale (EPOS) information now enable retailers to maximise sales and minimise stockholding by reordering smaller batches of garments in colours, sizes and designs to replace the garments that are selling in the stores. The short lead time and rapid turn round that can be achieved for cut and sew and fully fashioned garments using garment dyeing can thus outweigh the greater costs incurred by garment dyeing compared with the longer lead times expected from fabric dyeing.
Last year, the lower level of economic activity in the textile and clothing industries has stemmed from consumers using less of their disposable income to expand their wardrobe. Garment dyers in Asia have experienced a fall in orders from the USA and Europe, and have been looking at ways in which they can be more certain of right-first-time dyeing in order to improve productivity and profitability. Increasingly stringent regulations over the release of colour and chemicals into waste water treatment facilities have also forced garment dyers to look at more eco-friendly dyeing processes that can improve batch-to-batch reproducibility for repeat orders.
The class of dyestuffs used in garment dyeing is dependent upon the fibre substrate(s) present in the garment and the colour fastness levels required. Direct dyes are used for cellulosic fibres where the colour fastness levels required are low but acceptable to the retailer. The majority of cotton and other cellulosic fibre-based garments are normally dyed using reactive dyes that offer the consumer brightness of colour combined with high levels of colour fastness, especially to multiple domestic wash / wear cycles. The move towards lower temperatures in domestic washing machines in Europe has led to the use of washing powders whose cleaning performance is boosted by a cocktail of enzymes for removing stains and the use of a bleach activator. Dyemakers have evaluated their ranges of reactive and other dyes to ensure that the dyes used in garment dyeing do not change colour under multiple washing cycles using activated detergents.
Garment dyers are now looking for eco-friendlier garment dyeing processes and dyestuff manufacturers have responded to these demands in a number of ways. For the dyeing of garments containing cotton and/or other cellulosic fibres the ranges of reactive dyestuffs have been tailored for appropriate types and depths of colours. Huntsman Textile Effects, for example, recommend the following specific ranges of reactive dyes for garment dyeing. For pale to medium shades and / or for special / high colour fastness requirements, Novacron FN dyes are recommended.
Novacron NC reactive dyestuffs are recommended for dyeing pale to medium earth tone shades. For medium to dark and ultra dark shades Huntsman recommend Novacron S dyestuffs, and Novacron Super Black dyes for all kind of black shades.
Huntsman Textile Effects have introduced their Novacron S reactive dyestuffs based upon novel molecular chemistry that incorporates the use of strong and powerful chromophores with multiple and complementary reactive groups in concentrated formulations. These Novacron S dyestuffs thus provide very high build-up so that deep dyeings can be achieved economically. High build-up reactive dyes are eco-friendly because of their high fixation profile. This minimises the amount of unfixed or hydrolysed reactive dye in the dyeing effluent, which translates into lower waste water treatment charges, as well as facilitating ease of wash-off combined with high colour fastness. Rapid wash-off minimises water consumption and saves on processing time thereby contributing to higher machine productivity.
Deep shades are achieved with Huntsman's Novacron S reactive dyes |
An important feature of the reactive dyestuffs used in garment dyeing is that ternary (i.e. trichromatic) combinations of yellow, red and blue dyestuffs should be compatible and exhaust on-tone so that the colour depth builds up on-tone. In addition it is important that dyed garments that are likely to be washed frequently and line dried (as opposed to tumble drying) should not be subject to colour change on washing with activated detergents, i.e. so-called bleach fading. Another important parameter to retailers is that any fading that does occur, either due to washing or through exposure to sunlight during wear or line drying, should give rise to on-tone fading in order to minimise customer returns.
Drum dyeing machines require use less water
There are various categories of garment dyeing, each with its specific processing methods. Fully fashioned garment dyeing can be carried out with minimum agitation and a relatively high liquor ratio of 1:25 to 1:40 in paddle dyeing machinery. These have been particularly favoured for dyeing wool garments because the lack of agitation minimises the potential for felting during dyeing. More eco-friendly machines for garment dyeing include the drum dyeing machine that can be operated at a low liquor ratio and can be utilised for a variety of wet processing operations. Fully fashioned and cut and sew garments can be dyed in drum dyeing machines.
Cut and sew garments dyed to high colour fastness and boutique garments that may be dyed to a relatively lower level of colour fastness may be dyed in drum dyeing machines or in rotary drum dyeing machinery. The latter machine normally consists of a perforated stainless steel drum, which is suspended on a horizontal axis and divided into a number of compartments separated by perforated dividing walls. The drum can be rotated in both directions through the dye liquor, which is held in the bottom of the front loading machine, and the rotating drum machine operates at a more eco-friendly liquor ratio of 1:10. Such machines can operate at temperatures up to 140°C (e.g. for polyester garments) according to the machine design.
Seam penetration during dyeing can be difficult for some garment constructions, while other difficult dyeing conditions include the dyeing of garments containing viscose or elasticated waist bands. In order to achieve complete penetration of the structure, DyStar recommends the hot migration technique at 95°C using Procion H-EXL reactive dyes. This approach ensures that full penetration of the garment structure and level dyeing are achieved before the dye liquor is cooled back to a lower temperature when alkali is then metered in to ensure high levels of dye fixation. Procion, Remazol and Levafix reactive dyestuffs from DyStar are all used in garment dyeing. These high performance reactive dyestuffs meet all the colour fastness requirements set by retailers as well as being supplied under DyStar's well-established and highly valued Econfidence Program. Procion, Remazol and Levafix dye ranges thus meet the requirements of major ecology standards.
For deep saturated shades, DyStar introduced the Remazol Ultra RGB dyes with outstanding build-up and near perfect compatibility in ternary combinations. Shorter processing times, higher productivity and elimination of non-conformance thus provide garment dyers with higher cost-effectiveness. The innovative dye chemistry used in Remazol Ultra RGB dyes ensures high colour fastness in multiple wash cycles using activated detergents. Two other factors of increasing importance to retailers and brands are the minimal photochromism and minimised colour inconstancy between different light sources exhibited by Remazol Ultra RGB dyestuffs.
|
| We are collecting readers' comment for improving our website. If you are willing to help, please CLICK HERE to complete a survey. Your comments matter. |
|
|
|
|
| Copyright © Adsale Publishing Limited. Any party needs to reprint any part of the content should get the written approval from Adsale Publishing Ltd and quote the source "ATA Journal for Asia on Textile & Apparel", Adsale Textile English Website - www.AdsaleATA.com. We reserve the right to take legal action against any party who reprints any part of this article without acknowledgement. For enquiry, please contact Editorial Department. |
Write a mail to the editor : 
