Which French designer is known for pioneering the bias cut?

Madeleine Vionnet is the French designer best known for pioneering the bias cut in modern fashion.

A bias cut runs diagonally across the grain of woven fabric rather than along its straight or cross grain. This makes cloth more flexible and allows it to cling, drape and move around the body. Vionnet used the technique extensively in the 1920s, creating fluid dresses that contrasted sharply with the rigid corsetry and structured silhouettes common earlier in the century.

Vionnet did not literally invent every use of bias cutting; diagonal cutting had appeared in trims, skirts and other details before her. Her breakthrough was applying it to entire garments, turning the fabric’s stretch and drape into the central design principle. She often developed designs by draping and pinning fabric on miniature mannequins.

Her aesthetic drew on ancient Greek clothing and modern dance, especially the idea that garments should follow natural movement. Madame Grès also became famous for sculptural draping, but Vionnet’s full-length use of the bias became one of the defining technical innovations of twentieth-century couture.