As the fabric abrades or wears away during use, the white cotton yarn surface appears, giving denims a lighter or medium blue color. Contemporary or modern-day jeans are sometimes dyed in the fabric stage. These jeans have colored yarns in both directions and tend to retain their deeper color throughout the life of the garment. Normally, jeans with heavier yarns are expected to be slightly more durable. Some manufacturers use a variety of blend combinations, suc h as nylon reinforcement, as well as heavier yarns to increase durability.
Some denims have an extra layer of fabric fused to the inside knee area.
The process, which is referred to as vulcanizing, adds reinforcement and durability to the knee area. A variety of product treatments are available through modern technology. Among these are brushed denims and stretch denims. Brushed denims are napped on the surface for a softer look and feel. The fabrics may also be more flexible after napping.