Shimaoka was designated a Living National Treasure by the Japanese government in 1996. He is best known for developing a pottery technique in which white clay slip is applied to rope impressions made in the surface of the pot. After the slip partially dries, the excess is scraped away, leaving the lighter slip imbedded in the rope impressions. Shimaoka calls this technique Jo_mon zogan (Jo_mon inlay) after the rope marking found on ancient pots of the Japanese prehistoric Jo_mon era (ca. 11,000-400 B.C.E.). In evolving his technique, Shimaoka was also inspired by his father, a silk cord artisan. He commissioned his father to create differently braided ropes that resulted in unique patterns for his slip inlay.