This article investigates fresh indigo dyeing (saengch’ok) in the Chosŏn dynasty as a historical practice shaped by the interplay of material properties, artisans’ practical knowledge, and institutional arrangements. Drawing on late Chosŏn agricultural and technical writings, it examines how knowledge of indigo dyeing was recorded and gradually standardized in written form. The sources indicate a shift from mixed methods combining fermented and fresh indigo to an increasing emphasis on dyeing with fresh indigo alone. Rather than viewing this as a purely textual change, the article argues that the shift reflected practical knowledge developed in actual dyeing settings and later incorporated into technical writing. In this process, artisans’ responses to the heat sensitivity and instability of fresh indigo were especially important. A central feature of saengch’ok dyeing was the use of ice. Because this technique depended on maintaining low temperatures during the summer, it became closely connected to state systems of ice storage and distribution. Fresh indigo dyeing thus emerged as more than a craft technique: it was a historical practice in which materials, skills, and administrative order became closely linked.