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How a chemical agent manufactured by Evonik helps prevent fabric yellowing.
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Expensive, beautifully white designer blouses are a favorite item in many people's wardrobes. Normally, though, a yellowing of the armpit areas will become increasingly visible after each wash. This is an extremely annoying phenomenon. But what causes it? Deodorants cause discoloring and leave residue on fabric. Is the solution to stop using deodorants? Consumers often find this to be an extremely irritating problem, with internet forums full of ready advice on how to remove such staining before it completely ruins your clothes. Those tips include using lemon juice on the stains, fizzy headache-pill solutions or bicarbonate of soda — all of which don't really do the job. The manufacturers of antiperspirants have examined the problem to find out exactly what causes it and come up with better solutions.
Hamburg-based cosmetics group Beiersdorf was the first to succeed in this endeavor. Its "NIVEA Invisible for Black & White" antiperspirant uses a new formula that leaves less white residue on black fabrics while also reducing the yellowing effect on light ones. The successful development of this revolutionary NIVEA deodorant comes on the back of a highly unusual approach, namely to incorporate customers into the development process right from the start, even though any development work for new skincare products is normally shrouded in a cloak of absolute secrecy.
"We needed to come to understand how deodorant, perspiration, skin oils, and bacteria interact with textiles on the one hand and with laundry detergents on the other," says Dr. Stefan Biel from Prototyping at Beiersdorf. It was crucial to this exploration, therefore, to enlist the support of experts from the field of textile care — in this case, the prestigious Hohenstein Institute. The research involved exceptionally complex coordination and pinpointing of the right active ingredients. That is why Beiersdorf decided at the outset to bring Evonik on board to work hand-in-hand with its own development team. The experts at Evonik's Personal Care Business Line know their way around the formulas used for antiperspirants, and the company already supplies the raw ingredients (including cosmetic oils and emulsifiers) that go into making NIVEA products. Evonik's Household Care Business Line, on the other hand, has long years of experience with textile-finishing products such as fabric softeners. In a nutshell, therefore, the company had the requisite know-how in both the cosmetics and textiles fields.
This collaborative research was conducted at one of the biggest skin-research centers in Germany — at Beiersdorf in Hamburg. The scientists devised a special method to simulate the conditions which result in discoloration. "White armpit residue is caused mainly by the active ingredients in antiperspirants: aluminum salts," Biel explains. A solution was quickly found to protect black fabrics from staining. "We use a special technology by which the aluminum salts are dissolved in an emulsion and then coated in oils that make any residue invisible."
The problem of yellowing is a more complicated one. This discoloration is the result of a chemical reaction. "A reaction occurs in the washing machine when perspiration and the active agents in deodorant come into contact with the surfactants contained in laundry detergents," says Dr. Susann Wiechers, a chemical scientist at Evonik. "And interaction with lipids, or body fat, then produces yellow deposits that cling to the fibers." Testing performed on test subjects quickly showed that anyone using antiperspirants will eventually wind up with these unsightly stains on their clothing. How quickly such staining occurs and how pronounced it is varies from one person to the next, depending on the individual makeup of a person's perspiration, on how strongly they perspire, and on how oily their skin is.
Textile research has found that cotton fibers are especially apt to attract and retain foreign substances. After every wash, the fabric will show more discoloration and become increasingly stiffer. "This persistent discoloring cannot be removed through washing," says Dr. Jan Beringer from the Hohenstein Institute. "The fabric will eventually look really unsightly."
The researchers proceeded on the idea of finding an ingredient that would properly protect fabric and then integrating that ingredient into the formula for NIVEA deodorants. "We came up with a veritable bouquet of possible ingredients and structures," explains Evonik's Dr. Susann Wiechers. "Our meticulous search paid off when we identified a particular compound as producing exactly the effect we were aiming for. This active ingredient acts as a protective coating for the textile, thus preventing any staining effects from getting through to the fabric in the first place."
The researchers were also able to integrate this new agent, together with the other technology that prevents white residue on fabric, into stable, skin-friendly deodorant formulations for sticks, sprays, and roll-ons. The resulting product is NIVEA Invisible for Black & White deodorant, which now keeps that gorgeous designer blouse perfectly white. All over.