Enhanced wearability

German textile engineer Hans R. Bauer demonstrates how to redesign a conventional product using modern technology, new materials and a highly innovative mindset.

The dispensing machine’s nozzle sweeps over the black-gray synthetic fabric msade of Lycra and polyamide fibers in long, flowing movements and traces the outlines of a garment with a colorless liquid silicone rubber. A red laser cross marks the beginning and end. The latest technology is being used here in Balingen in the Swabian Alb region of southern Germany to create a conventional, albeit new-look item of clothing: a sports bra.

Once the bra straps have themselves been reinforced with three vertical silicone strips, the equipment takes a short break, heats up the 3D print head and then moves toward the bra cups. At the curve of the cup, the dispenser squeezes a reinforcing polymer – an elastic polyamide – into the silicone bed.

“By replacing the traditional metal underwire of a sports bra with silicone and polyamide, we are creating unrivaled wearability,” says Hans R. Bauer, managing director and founder of New Textile Technologies (NTT). NTT refers to this patented, wire-free technology as SensWire. According to Bauer, the traditional metal underwire has been the subject of some debate in terms of health over recent years. It is true that the German Cancer Information Service (DKFZ) has given the all-clear – a correlation between wearing a bra (with or without an underwire) and the onset of cancer cannot be proved. Yet many women are looking for softer alternatives to the rigid metal underwire – and the structural design developed by Bauer makes these alternatives possible.

An elastic material such as silicone – possibly reinforced with another synthetic material such as polyamide at critical points like the bra cups – molds much better to the human body, thereby preventing painful pressure marks.

Bauer likens the bra-manufacturing technique that he developed to the structural principle of suspension bridges such as the Golden Gate Bridge. The bra straps work like pylons – the towering static bridge piers to which flexible support cables are fastened. In a bra, the long, vertical strips of silicone coating applied to the straps act as the support cables, which hold the actual weight of the breast. These silicone coatings are reinforced by another synthetic material (polyamide) at the bottom of the two cups.

Once the bra has been completely reinforced with silicone, a member of staff takes it out of the dispenser. Detailed silicone patterns that are created by NTT’s own textile designers and which cannot be produced by the dispensing machine are added on site by means of screen printing.

The next step is so-called flocking. An electrostatic metering device that is reminiscent of a pepper shaker is used to apply black-gray polyamide flocks – just like in powder coating – to the lines of silicone while they are still damp. This approach is required by the design, but it also necessary so as to suppress the natural tackiness of unflocked silicone. Such tackiness may well be desirable, however, on the inner surface of textiles to ensure that the garment hugs the body.

Optically, the bra is now perfect. It is then placed into the drying unit, where it is heated to 145 degrees Celsius for ten minutes to allow the silicone to cure.

Yet as is so often the case, there is more to this design than meets the eye. Developed by NTT experts, SensElast 3D technology for the seamless production of clothing ensures that the sports bras made in this way are extremely comfortable to wear.

“Underwear produced by this technique feels like a second skin,” says Bauer. At this year’s ISPO – the world’s biggest tradeshow for sports articles – in Munich, the Balingen-based company received the “Health & Fitness – Sports Bra” award for its SensWire and SensElast 3D technologies.

The seamless production of textiles – known in the industry as tubular fabrics – is one of the core skills of NTT, which Bauer founded in 1999. “I’ve always had the urge to invent something,” recounts Bauer, who is a trained textile machine mechanic. He previously worked as a technical manager in his father-in-law’s knitting factory. And it was in this capacity that Bauer, who holds several patents, learned the many skills that he later brought to his own company: expertise in stitching and materials, the development and installation of machinery, the specification of customer requirements, textile design and much more. Thanks to the production processes he developed, Bauer, in a manner of speaking, reinvented the manufacture of ready-to-wear textiles twice.

Although NTT’s portfolio includes the production of individual series, the company’s core business is prototyping. Bauer and his 25 employees – including several textile engineers from the nearby Albstadt-Sigmaringen University of Applied Sciences – develop innovative technologies and processes, which leading manufacturers then use in their production. “We employ laser cutting, ultrasonic welding, dispensing and screen printing with silicone – not everyone can do that. Over the last 15 years, we’ve gained expertise in the manufacture of smart textiles,” emphasizes Bauer.

NTT’s official licensees include, for example, MAS in Sri Lanka – one of the world’s biggest contract manufacturers of underwear, sportswear and other textiles that employs some 100,000 people and supplies almost all major clothing brands worldwide. What’s more, NTT has been operating its own production plant in Croatia since 2016, where it makes the products developed in Balingen.

Due to high personnel costs, virtually no clothing or sports-goods manufacturer produces standard articles in large series in Europe anymore, but Bauer hopes that the highly automated technology he developed will make the manufacture of high-quality clothes interesting there again. A bra consists of around 40 parts. With Bauer’s technology, the entire basic assembly runs on one line. Bauer and his textile engineers are currently working on a machine that acts both as a dispenser and can handle silicone screen printing with its highly multifaceted design possibilities – “a kind of jack-of-all-trades.”

Now NTT’s head of development and owner, Bauer first came across silicone as a material some 20 years ago when a large German textile manufacturer was looking for ways to improve its high-quality bodysuits. The problem, explained Bauer, was that this kind of underwear was primarily targeted at older customers, which meant the product had to meet specific requirements. The bodysuits needed to have integrated supports for assisting the connective tissue. These kinds of supports tighten up and shape the body. The product that Bauer developed showed that silicone could be used in such bodysuits without the need for a visible and uncomfortable seam.

To combine functionality with wearability, NTT uses a two-component liquid silicone rubber (LSR) from WACKER. The material is slightly pigmentable and exhibits good mechanical properties. Moreover, the liquid silicones used require only short curing times – a key property in the textile industry, since it relies on fast throughput. After curing on exposure to heat, the silicone is bonded to the synthetic fiber fabric underneath it. The product is lent properties that provide support and it remains elastic, in both cases without additional bonding.

This unusual property profile makes the range of applications truly diverse. For instance, a silicone coating can replace the elastic strips that had previously been glued or sewn into women’s hold-up or thigh-high stockings and men’s underpants. The silicone layer on the rim of the pants or stockings ensures that the textile fits sufficiently tightly on the body and does not slide off. The silicone can also be left exposed on the textile’s inner waistband to act as an anti-slip coating that reinforces the hold.

In the early years, Bauer and his employees also experimented with other materials, such as polyurethane, as support materials for underwear and sportswear. However, he quickly came to the conclusion: “There is nothing quite like silicone on the entire market.”

Silicone rubber compounds even make considerably more ambitious applications possible. On behalf of Antelope, a Frankfurt-based startup, for example, NTT produces a compression sports suit with integrated electrical muscle stimulation (EMS). During a workout, a slight voltage that is supposed to stimulate muscle growth and, at the same time, shorten recovery time is applied to the suit. It is possible to apply a voltage, because the inside of this sports suit is coated with silver and a specialty silicone from WACKER that is filled with carbon black – and is thus conductive. Bauer believes that the future of the German textile industry lies in these kinds of high-end, possibly custom-made, products. “The evolution of traditional underwear is far from complete,” he says.