IT WAS THE flannel that shot across the internet. In mid-November, actor, producer and perennial hair icon Brad Pitt was handing out groceries in Los Angeles as a charitable gesture in the lead-up to Thanksgiving. The paparazzi on hand captured Mr. Pitt’s charmingly casual outfit: a pair of white slip-on sneakers, distressed (but likely pricy) blue jeans and a flannel shirt with an unusually intense red, black and white check pattern. That beguiling flannel stole the show and fans raced to identify it. Though they floated many theories online, few picked the right brand: A representative for Mr. Pitt confirmed that the shirt is by God’s True Cashmere, a minuscule shirt company run by holistic healer and jewelry designer Sat Hari Khalsa, whose cashmere flannels can be had for around $2,000.
Even in the grainy, zoomed-in photographs that colonized the internet, it was possible to decipher what made Mr. Pitt’s shirt special, apart from its breathtaking price. The flannel itself was far hardier than the wafery material you usually find at shops like the Gap or Uniqlo. And its tri-colored checks were atypically large and graphic, shot through with fine, dotted lines.
The pattern’s blown-out scale is what takes this flannel from a simple shirt to a sensation. Dan Snyder, the owner of Corridor, a Brooklyn-based clothing label, described the print as a “macro” plaid: It’s as if a plaid pattern were viewed under a microscope and then a shirtmaker transferred that zoomed-in perspective onto a button-up. Mr. Snyder noted that few textile manufacturers actually make such overscaled patterns today. That’s why eagle-eyed commenters online were convinced that Mr. Pitt’s flannel had to be vintage, with some specifically pointing to brands like Big Mac, a workwear label started by JC Penney in 1922.
A few years ago, Mr. Snyder stumbled across a shirt scrap with a similarly exploded pattern that he guessed dated to the 1930s—and he took inspiration from it for his company’s Acid Plaid shirts. These wavy flannels echo the loud nature of Mr. Pitt’s (some customers asked Mr. Snyder if the “Ocean’s Eleven” star was wearing an Acid Plaid in the celebrated photo) at a much quieter price point.
Other more-affordable Pitt-like plaids come from brands like Freenote, Sugar Cane and Warehouse which produce, with a very reverent touch, workwear staples evocative of decades past. Made from cotton, their burly blown-out plaids might not match the cashmere prestige of Mr. Pitt’s shirt, but at around $1,700 less, they offer savings that more than offset the trade-off.