Ai (藍 [ai])

Ai is indigo dye, historically used both as a standalone colorant and as a modifier to shift other traditional color systems toward blue/green. In urushi contexts, “ai” may refer to the dye itself (from indigo plants) and to the color family it produces—deep blue that can read almost black depending on layer thickness and lighting. Ai-based coloration tends to look more “alive” than flat synthetic blues because it can carry subtle brown/green undertones. In modern practice, many “ai-like” blues are achieved with synthetic pigments, but the term still signals the aesthetic intent.