By and  on July 13, 2005

In what is probably a first, Portuguese manufacturer Petratex is constructing activewear for Nike using only fused seams and no thread.The three-quarter-inch seams are overlapped and, depending on the fabric, bonded with ultrasound or a combination of glue and heat.The main advantage of the process is that it produces seams that will not break, a benefit in activewear. The fused seams are slightly bigger than sewn ones, but they are not stiff or thick. What's more, they can stretch and retain their shape."You can rip either side of the fabric," said 38-year-old Petratex managing director Sérgio Neto, demonstrating with a torn polyester material. "But the seams remain intact."Although Petratex is currently using the process for activewear, Neto says he believes the technique can be applied to fashion, including eveningwear.The process has been in development for three years and is now in production at Petratex headquarters in Paços de Ferreira, Portugal. As of June, the factory was turning out 1,000 "no sew" garments a day using patented machines that Neto created. The items include jackets, tops, dresses, pants, skirts and shorts.Sixty percent of that production is for Nike; Petratex declined to name the other brands. Nike's first all-fused garments will reach stores in spring 2006, Petratex said.The company did not invent ultrasonic or adhesive bonding, although it appears to be the first to use fused seams in activewear to create entire garments. The company is in the process of patenting its technique in countries on four continents.Sonic bonding has been in use since at least the Sixties, said Ian Butler, director of market research and statistics for the Association of the Nonwoven Fabrics Industry, based in Cary, N.C. Typical applications include attaching quilt backings and assembling surgical gowns. Sonic bonding works only on synthetic fabrics, and it is faster than glue because it doesn't have to dry, he said. The ultrasonic vibrations are so fast that they create heat and melt the plastic fibers together, said Jud Early, chief technology officer for [TC]2, a nonprofit apparel and technology organization also based in Cary.Adhesive bonding can be used on any type of fiber. Sara Lee makes a bra constructed entirely with adhesives, and Haggar Apparel Co. used glue in select applications, such as facings, pockets and belt loops in men's pants, starting in the mid-Seventies, said Early, who used to work at Haggar. The process cut the number of machines and operators needed to create a component, such as a pocket, from four or five to one, which saved the company time and labor costs. However, the machines were expensive, so the return on investment took about twice as long as usual, he said.Johnson & Johnson used to glue together surgical gowns using only robots, Early said, but recently moved its production from Texas to a traditional factory in Mexico."I think it's a specialty item," Early said, referring to bonded seams in general. "If it's done for a specific purpose, it has a lot of merit. The quality you get using bonded seams is phenomenal." But a garment created entirely with bonded seams cannot be altered, he noted, and with cheap labor available around the world, the cost of the equipment to automate the process may be difficult to justify, he said. Apparently, Petratex is not using the process to speed production; it said its technique takes 10 to 15 percent longer than traditional construction. Three years ago, Petratex began experimenting with limited treatments and details, decorative patterns and trims such as stripes and waves. Later, Nike asked the company to produce a completely thread-free garment, Neto said. The 31 million euro, or $39 million at current exchange, company began in 1989 as a maker of embellished blouses. It produces 20,000 sewn pieces daily for large activewear and luxury companies such as Adidas, Patagonia, Prada, Armani, Dior, Escada, Girbaud and Diesel.Future fusing-related techniques on the company's drawing board include water-repellent seaming and a stamped-like "molding" process that puffs up decorative lettering and symbols on a variety of fabrics, from denim to polymesh.

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