Jōmon Zōgan (also called “Nawa Zōgan”) is a decorative ceramic technique that involves impressing rope patterns onto a piece and inlaying clay of a different color into the grooves.
This technique was developed by Tatsuzō Shimaoka. He drew inspiration from two main sources: the decorative methods used on Jōmon period pottery, which he studied while making teaching models at the Ceramic Research Institute, and the inlay technique known as Mishima-de from the Joseon Dynasty in Korea.
What brought these influences together was something close to home—his father's silk braiding. Shimaoka used braided cords, rolling them across the surface of semi-dried clay to create rope-like impressions. He then filled these impressions with white slip (liquid clay) to complete the Jōmon Zōgan technique.
The process begins by shaping the ceramic piece and allowing it to dry to a leather-hard state. Then, a rope is rolled over the surface to create the pattern. Next, a white slip is applied over the entire piece, filling in the indented areas. Once dried, the surface is gently scraped off, removing the slip from the raised areas but leaving it in the recessed rope patterns. This reveals the contrasting colors—slip in the grooves and the base clay on the flat surface.