Bias cut and the triumph of anisotropy

The bias cut (or byesse cut) is a technique used by designers for cutting clothing to use the greater extensibility in the diagonal direction of the fabric. Woven fabric is more deformable in the bias direction (the Poisson modulus is larger), compared to the on-grain direction.

Every piece of woven fabric has two biases, perpendicular to each other. Non-woven fabrics such as felt or interfacing do not have a bias. If cloth is pulled on one of the bias direction it stretches in that direction and gets shorter in the perperdicular direction. Like this the shear deformation of the cloth accentuates body lines and fits better to the figure. Also, this property facilitates details that require extra elasticity, drapability or flexibility, such as neckties, trims, decorations, boundaries and seams.

French fashion designer Madeleine Vionnet (in the picture below) popularised the bias cut clothes and dominated haute couture in the 1930s setting trends with her sensual dresses worn by stars as Marlene Dietrich, Katharine Hepburn and Greta Garbo. Vionnet's vision of the female form revolutionised modern textile industry.





Note: Based on the story published in Structures or why things don't fall by Prof. J.E. Gordon, 1987.