A Buddhist statue made of cast iron. Cast iron statues were not as common in Japan as bronze (see *dōzō 銅像). Iron was harder to work than bronze, and did not produce such a fine surface texture. Some scholars believe that cast iron was sometimes used instead of bronze because it was cheaper, but there is some doubt about this because iron needs to be cast at a higher temperature, thus increasing the production cost. It was likely that cast iron statues were made because the rough, hard texture suited the taste of the samurai classes in medieval Japan and was similar to the expressive style popular in wooden statuary at that time.
The technique used to produce the vast majority of cast iron statues was the split-mold method warikomegata 割込型. A clay or wooden model of the statue was covered by another clay layer which after drying was split and rejoined to make a mold. Into this was fixed an inner mold *nakago 中型. Molten iron was poured into the space between the two molds, and removed when it had cooled. Small statues were cast without using the inner mold, and were therefore of solid iron (not hollow). The lost-wax *rōgata 蝋型 method of casting popular for bronze statues was not used for iron. Because of the hardness of iron, it was difficult to smooth the surface with a graver, and so irregularities, protrusions left after casting *hari 梁, and pins used to secure the molds *kōgai 笄 are still visible in many finished works.
Korean cast iron statues exist from the end of the Shiragi 新羅 era (9th century) though to the Kōrai 高麗 era (10th-14th century), and in Japan there are approximately 90 examples preserved from the Kamakura and Muromachi periods, about 90% of which are located in east, north-east, and central Japan. These include the Amida zazō 阿弥陀坐像 from Zenmyōji 善明寺 (1253) in Tokyo. Other cast iron statues are the Amida sanzon-zō 阿弥陀三尊像 in Fukutokuji 福徳寺, Saitama Prefecture, and the Fudō Myōō-zō 不動明王像 in Ōyamadera 大山寺, Kanagawa Prefecture.