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By Max W. Sung

Structural colours for textiles: Humans, with their inherent lack of body covering, have since antiquity made clothing to protect them from the elements. They have also harvested the colours in nature to adorn their clothing for purposes of attracting mates and for designation of social hierarchy. Carmine, a pigment harvested from dried and crushed cochineal insects, became Central America's second most valuable export next to silver following the Spanish invasion of the Aztec empire, and was used in the robes of Catholic cardinals. Tyrian purple, a pigment prepared from the mucus of Murex snails, was a symbol of wealth and power in the Greek and Roman empires. Ultramarine blue, the most expensive pigment from the Renaissance era and prepared from crushing the semi-precious stone lapis lazuli, was used in manuscripts and in paintings by famous artists, including Vermeer.

It is appropriate therefore that blue was the first synthetic pigment developed in 1706. Prussian blue, as the new pigment was called, was produced by oxidation of ferrous ferrocyanide salts to its coloured ferric salt. In textiles, the relatively inexpensive Prussian blue was used extensively in the uniforms of the Prussian and other armies. The Industrial Revolution in the nineteenth century subsequently witnessed the explosive growth of the synthetic dye industry, with pigments developed for every shade and hue.

Colours from pigments result from absorption of specific ranges of wavelengths of visible light; the resulting wavelength which has not been absorbed is reflected back and is perceived by the human eye as the colour associated with that pigment. Newton has shown that colours are derived from visible white light and correspond to various wavelengths ranging from 390 to 700 nm.

In nature, many colours are not associated with pigments. For instance, the brilliant blue in the berries of the African herb Pollia condensata is not extractable as a pigment. The blue colouration is actually determined by Silvia Vignolini and her colleagues at the University of Cambrdige to result from light reflection from helicoidally stacked cellulose microfibrils that form multilayers in the cell wall. The distance between these microfibril layers is close to the wavelength of blue light. As a result, blue light is reflected while other wavelengths pass through and does not reach the human eye. Scientists have reported that many colours in nature, such as the feathers from the male peacock and from the spangled cotinga bird (see cover of Textile Asia, June 2014), are also not derived from pigment but from light reflection on multiplayer structures. These colours are termed structural colours to distinguish them from pigment-derived colours.

The successful large scale production of synthetic dyes and pigments and the effectiveness of how these dyes can be applied to textiles fabrics and fibres are responsible in part for the development of the textile production industry.

Since 2010, a number of scientific researchers have reported on their success in producing artificially nanoparticle multilayers which mimic the structures in nature which produce structural colour. These synthetic multilayers have also been demonstrated to produce structural colours in the absence of pigment.

Researchers at Teijin Fibres were able to reproduce the nanostructures on the Morph butterfly wing by combining polyester and nylon fibres in alternating layers. By controlling the thickness of each layer, they were able to produce four basic colours (red, green, blue and violet). Depending on the intensity of light and angle at which light reaches the layers, a rainbow of colours can be produced. Morphotex fibres which can produce structural colours were in production only for a short period of time, from 2010 to 2011.

Researchers at the NanoPhotonics Centre at the University of Cambridge, England, in collaboration with researchers at the Frauenhofer Institute for Structural Durability and System Reliability in Germany, have developed a synthetic material Polymer Opal which shares structural characteristics as natural opals. Unlike natural opals, Polymer Opal is made of spherical nanoparticles bonded to a rubber-like outer shell which settles into identical layers upon evaporation, resulting in a uniform colour. When the film is stretched however, the distance between layers is changed, resulting in shifting shades of colours. Polymer Opal has been incorporated into fabric in the Rainbow Winters collection in 2012 as Liquid Fabric Stretch Reactive Bodysuit. This marked the first time that synthetic structural colours were exhibited in the fashion industry.

The same researchers have since developed a method where patterns can be printed into the polymer material using a printhead that incorporates an electric field. Varying voltage as the nanospheres are being laid down affects the spacing between them, changing the colour for that area. The nanospheres are then fixed in place with UV light.

Yingying Diao and Xiangyang Liu, researchers from the University of Singapore and Xiamen University, have also reported on the synthetic production of photonic crystal structures to mimic the biological structures responsible for structural colours. Both organic and inorganic materials were used in the production of photonic crystals. The researchers have developed the methodology to apply 3-D photonic crystals on the surface of silk fabrics.

Vinothan Manoharan and colleagues at the Harvard School for Engineering and Applied Sciences have in March 2014 reported on a system where microcapsules can be brought together upon evaporation of the aqueous medium, but do not need to be ordered to produce structural colour. It is the average distance between the microparticles, rather than the ordering of the particles that determine the wavelength of the structural colour.

Potential applications include paints, coatings and electronic displays. Commercialisation of the technology is in progress. The potential advantages of synthetic substrates that produce structural colours are energy efficiency and reduction of industrial waste since no dyeing process is involved. In addition, if these substrates can be effectively applied to textile fabrics and fibres, the resulting structural colours may not fade over time. It remains to be seen if synthetic structural colours can be effectively commercialized and be incorporated into the textile dyeing industry .












Special Reports

  • Asian Age is unfolding for textile machinery industry: Textile machinery industry has gone through some stunning phases over the past century and more. Until the 1960s, textile machines were made mainly in Europe. Shipping them from Europe to Asia then was a protracted affair, often taking as long as a year. Now the situation is different. Europe is not the only producer of textile machinery; they are produced in many parts of the world.

    In the 1980s, machines made in China as well as in other Asian countries began appearing at textile machinery shows. A latest example is the ITMA Asia + CITME held in Shanghai in June. Asian-made machines are not as sophisticated as the European-made, but they fulfil the needs of cost-conscious textile and clothing manufacturers in many developing countries and they are improving in quality as time goes by. The challenge this Asian trend is posing has prodded some European manufacturers to consider a new option - set up production plants in Asia, either on their own or in partnership with local entrepreneurs, to reduce production and delivery cost as well as to shorten delivery time. Those who took this path have fared well and their business flourished. Many examples of such East-West cooperation could be seen at the ITMA Asia + CITME show, which in effect represented the internationalisation of textile manufacturing industry.

    As European textile machinery makers began establishing production and marketing bases in Asia, textile industrialists in Asia have also started expanding their activities within Asia and, more notably, acquiring textile technology ventures in the West. India's Lakshmi Machine Works opening a new US$29 million plant in China, CCI - a company that Taiwanese and Hong Kong entrepreneurs started for producing machines that can make textile samples, Crosrol Shanghai that began as a Chinese-European partnership for making blowroom and carding machines and now operating as an independent company, China's Hisun Group acquiring Germany's Grosse as it fell into financial difficulties, Fong's industries taking over THEN, Goller Xorella, and Monforts and subsequently China Hi-Tech Group Corporation acquiring Fong's as well as Autefa Solutions of Germany and JW-Protti Macchine Tessili of Italy thus emerging as the largest supplier of complete range of textile machinery for the entire textile production line from cotton spinning, chemical fibre, weaving, knitting, printing, dyeing, nonwovens and textile components in China besides exporting them to 50 other countries are just some of the examples of the dawning of the Asian Age in the textile sector.

    By Vicky Sung

  • Times to Remember: Picanol celebrates over half century of presence in China: Belgium's 78-year-old globally leading manufacturer of weaving machinery was one of the early European explorers ventured out to tap the market for textile machinery in China. Today, it has a wholly-owned subsidiary in the country and a fifth of the machinery it sells are made in China.

    By Alpana Shrestha

  • Polyester price is increasing, so demand for cotton will rise: Polyester price that had fallen to 65 US cents a pound last April has since risen to 73 cents. In contrast, cotton is becoming cheaper than polyester, driving consumption towards 24.5 million tons in 2014-15.

  • World production of yarn and fabrics: Production of yarn and fabrics in the current (third) quarter of this year is estimated to be positive in Asia, according to the International Textile Manufacturers Federation.

Regional Notes


  • A decisive move to uplift cotton output: Bangladesh, the world's second largest garment exporter, but not much of a cotton producer to figure among the 31 cotton producers listed in the annual ranking of the National Cotton Council of America, is making an attempt to promote cotton growing in the country. The country's Cotton Development Board is aiming, according to its executive director Md Abdul Latif, to increase domestic production gradually to 670,000 bales (113,900 tons) by the end of 2021 or some three times as much cotton as the West African country Togo produced last year to rank 31st in the US National Cotton Council listing. Locally produced cotton meets only some 3-4% of Bangladesh's current demand for raw cotton, Mr Latif told the Cotton Research and Development Network meeting in Dhaka in June.

  • IFC credit line for Bangla apparel maker: For the first time since it launched the US$500 million multi-currency financing program in 2010 as a credit facility that is affordable for suppliers in emerging markets, the International Finance Corporation (IFC) has extended it to an apparel manufacturer in Bangladesh. Thus, the MBM Group, a Dhaka-based apparel supplier to global brands like Dockers, Denizen, Levi Strauss, etc., will receive a credit line against receivables from one of its major international buyers, Levi Strauss. The managing director of MBM Group, Wasim Rahman, describes the deal as much more than obtaining an affordable credit facility. "We are paving the way for others in the sector to avail of the facility and obtain affordable short-term finance," he says.

Sri Lanka

From A.H.H. Saheed, Colombo

  • Garment exports up 23%: Garment shipments from Sri Lanka in the first quarter of this year increased by almost 23% to US$1.2 billion, according to official trade figures. Exports of made-ups and yarn also increased significantly in terms of growth percentage, but they were the smallest in volume and value.

Products & Technology

  • Hyosung takes another step to make the world more beautiful: Hyosung has launched a new eco-friendly elastane, creora easy scour. Its special attribute is that while it fulfils the quality requirements of mills that are using finer yarns as well as finer gauge knitting for the production of more delicate fabrics, it reduces water usage as well as residual oil on fabric surface after scouring. As a result, mills can dye and finish more efficiently, improve mill quality and, above all, enhance the colour appearance of fabric. The technology was developed using Hyosung's proprietary finish. As colour, softness, compression, shaping, fit, and function continue to drive consumer demand, creora easy scour is a significant achievement, says Hyosung's president, C.H. Kim.

  • A new PFAFF for tactical vests: PFAFF Industriesysteme und Maschinen, the 132-year-old German producer of sewing technology, has released a large-area sewing unit, PFAFF 3590, with zigzag machine head and special applications for sewing areas up to 850 x 400 mm.

  • Dyes for PA fabrics: Huntsman Textile Effects which introduced late last year the Dicrylan Shade Deepener that can deliver unparalleled colour depths on all fibres without any compromise on fastness properties is now extending its Lanaset range of dyes to deliver additional bright shades for woven and knitted polyamide (PA) fabrics.

  • Best geotextile for road building: TenCate Mirafi RS580i woven geotextile is found to have outperformed all geosynthetics that the Western Transportation Institute at Montana State University in the United States has tested recently.

  • Software to ensure perfect pattern design: A new software that can greatly enhance pattern design accuracy for any garment of printed fabric and eliminate the time and costs of creating physical samples has been released by Optitex, a provider of 2D and 3D CAD/CAM and virtual prototyping software solutions for sewn products.

  • A new outerwear fabric from Teijin: A high-comfort, high density fabric that as an uncoated material can offer excellent moisture permeability, a comfortably soft texture and a luxurious surface appearance, all qualities that make it a perfect for outerwear, has been developed by Teijin Frontier Co., the fibre- products converting member in the Teijin Group.

  • Software to reduce time from design to delivery: An apparel design software that allows designers to work with more complex knit and woven structures for creating sophisticated design options and clear and concise range plans for clients as well as to shorten time to market by improving control and visibility at the deepest level, has been developed by Lectra, the supplier of integrated technology solutions to industries using soft materials like fabrics, technical textiles, leather and composite materials.

  • Technology to transform nonwovens: The US company, Micrex Corporation, which is based in Walpole, Massachusetts, has developed a new technology that can transform nonwovens from 2D to 3D materials while also adding properties such as softness and stretch. This technology is said to offer a huge advantage over traditional embossing .

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