Woolmark's wool denim reference describes placing wool in the weft yarns so that it appears on the inner side of the cloth. This changes the material against the wearer compared with conventional all-cotton denim. The source connects that placement with warmth and moisture-related comfort.

Put Wool in Denim's Weft to Change the Inner Surface

Specially treated wool supports the care approach described for these fabrics, while elasticity and odor behavior are additional development considerations. These features belong to a specified denim construction and treatment. A denim appearance alone cannot reveal whether wool is present or establish the washing instructions of a particular pair of jeans.