Why no two Kyoto iron kettles are alike
Heian Shojudo opened on Kyoto’s Teramachi street in 1885, working mainly in copper and iron. Kyoto Prefecture lists it as a Kyō no Shinise, the register of long-established Kyoto houses.
Their iron kettles are cast in sand. The mould is packed around a pattern, the iron goes in, and the mould breaks apart as it is poured — there is no master mould to reuse. Every kettle therefore comes out of a mould that existed once, for that kettle, and the surface of each one is slightly its own.
Rust is handled by a method roughly four centuries old: the kettle is fired at about 800°C so that an oxide skin forms on the iron, then lacquered and fired again at about 240°C. Nothing is coated on afterwards to make it shine.
Iron work of this kind is heavy, slow and hard to scale, which is why so little of it survived the twentieth century — a good deal of Japanese metalwork was melted down during the war. What is on the shelf now is the part that came back.