The zipper keeps everything from jeans and jackets to duffel bags and lunch boxes closed tight. Still, for all its simple utility, a fastener that won’t budge has caused frustration in nearly everyone ...

If you’ve ever had a zipper get stuck on a bag, sweater, or a coat, you’re familiar with the frustration. It can feel like there’s nothing to be done but surrender to a stubborn zipper and toss the ...