Indigo sewing thread: Indigo dye does not completely diffuse to sewing thread. After industrial wash the color of the indigo dyed sewing thread fades away. This is the expected effect and the reason why this special dye is used. Depending on the type of wash, Indigo dyed sewing thread has different effects. It is mostly used in denim. The spec 602, 603, 452, 402, 403, 292, 293, 302, 303, 162, 163, 152, 153, 123, 202, 203, 204 are available.