What’s the deal with those slightly shiny workwear shirts everyone’s so crazy about, and what makes them “chambray” and not just cotton, or denim? Well, chambray is indeed made of soft cotton—usually either Egyptian or American (or even flax)—and woven with a colored warp woven against a white weft. The fabric is then rolled and cooked at high heat in the same way as playing cards, to achieve that durability, stiffness, and sheen. Those shirts—historically worn by workers and prisoners the world over—are of course the most famous incarnations of chambray, and are made using an indigo dye warp (whence the terms “blue collar,” and “prison blues”). Favored by a roguish new wave of Hollywood movie star in the 1970s—picture Redford, Newman, and McQueen—chambray shirts took a macho blue-collar look uptown. With the Gyllenhalls, Renners, and Goslings of the world inheriting that mantle, and heritage fetishists celebrating the hell out of its killer modern day incarnations, this fabric invented in the French city Cambrai during the 16th century is here to stay.