Union delivers a take on workwear staples for its spring ‘23 collection by pairing unexpected textiles with colorways that break from the style’s traditional neutral color palette. Inspired by those fly ‘70s leisure suits, Union’s offerings include carpenter pants using custom yarn-dyed plaid in olive, blue, pink and brown.

Mr. Winthrop specified that he wanted to make yarn-dyed flannel, not flannel in which the pattern is simply printed onto the fabric.

He needed good yarn-dyed fabric to make his shirts.

Portugal and China are today the main producers of yarn-dyed flannel, Mr. Herman said.

What gave Mr. McKinnon confidence initially was that Cotswold held onto a tiny piece of the yarn-dyed shirting business that involved uniforms for the Metro-North and Long Island Railroads.