Now, nylon comes in killer colors.

Sock science marches on. Last year, researchers at the University of California, Davis and HaloSource Corp. in Seattle developed a treatment that makes white cotton fabric a death zone for disease- and odor-causing bacteria (SN: 9/11/99, p. 170). Consumers could soon see athletic socks made of the fabric, which is laced with compounds called N-halamines.

The treatment lasts through 50 washings, but its activity has to be refreshed with bleach during each wash. That's fine for textiles used in medical settings because they're sterilized before each use, anyway. Consumers, on the other hand, find it very inconvenient to bleach their whites every time they do laundry, and bleach and colored clothes don't mix, says Gang Sun, the UC-Davis researcher who led the work.

Sun and Lei Qian, also of UC Davis, have now come up with a treatment, a cyclic amine compound, that will keep its killing power through five washes before it has to be recharged. This antibacterial finish sticks well to natural fabrics like cotton, but nylon and other synthetics are made of slick polymer chains that have nothing for the finish to cling to.

So, Sun and Young Hee Kim of UC Davis created footholds for the antibacterial coating by treating the nylon with acid dyes. These dyes both color the fabric and grip bacteria-killing quaternary ammonium salts. Kim and Sun have used blue, red, violet, and yellow dyes, but they say any color should work.

The researchers say that the dyes improve the durability of the antibacterial finish. Kim estimates that clothes can stand up to 50 spins through the home laundry and keep their antimicrobial power if they're recharged during each wash.

Neither the longer-lasting whites nor the killer-color fabrics are available for purchase, yet. Sun says the first generation of antibacterial sweat socks should be on the market in time to go "back to school" and make next fall's gym bags sweetersmelling places.