Sumizome is a dyeing technique that uses powdered bamboo or wood charcoal to permeate yarn and fabric. It is characterized by a unique silvery look that appears in the gradation from gray to black. The charcoal itself does not deteriorate when exposed to ultraviolet rays, so the color changes little even after dyeing, even when exposed to sunlight, and the color remains stable for a long time. At MITTAN, we dye our products in a dyeing factory in Okayama using a large washing machine-like dyeing machine called a washer.