Because of the above history, tea bowls produced by using tetsuyu were called 'Tenmoku,' and among them, those with a supponguchi (a mouth in the shape of soft-shell turtle) were specifically called 'Tenmokujawan,' being valued by tea ceremony lovers because of their excellent ability to keep tea warm and used at important tea ceremonies such as Daisu-temae and Kijin-date.
この事から、鉄釉のかかった茶碗を「天目」と称し、その中でも特に鼈口を有した2段の口造り構造となった天目の茶碗は中の茶の保温に優れたものとして茶道を愛好するものに好まれたために、こうした茶碗を「天目茶碗」と呼んで珍重して、台子点前・貴人点などの重要な茶会などの際にも用いられた。