The town of Mizusawa in Iwate prefecture has been a major producer of cast metal since the Heian period (794–1185). Today it is home to as many as 100 factories. Among them, Oigen Foundry Co., Ltd., incepted in 1852, continues to forge traditional Nanbu ironware renowned for its unblemished smooth surface and classic good looks.
Oigen Foundry makes timeless kitchenware for professional chefs, adopting modern designs within the tradition of Nanbu ironware. Its two-handled cast- iron plates are found in restaurants throughout Japan, but we’d like to introduce a series that the ironworks has created in collaboration with British product designer Jasper Morrison.
The commission was, for Morrison, an introduction to the world of iron casting. Nevertheless, his deftly designed simple shapes reveal how closely he studied the Nanbu ware tradition. Among his advisors was chef Katsuyasu Ito of the French restaurant L’auréole in Iwate. A holder of a Ryori Master award given by Japan’s Ministry of Agriculture and a longtime aficionado of Nanbu ironware, Ito has nothing but kudos for how user-friendly Morrison’s Chef series is. Though made of the same material and sporting the same thickness as traditional Nanbu cookware, it carries a much lighter heft in the hand, just one of its many notable features.
In the final stage of production, Oigen fires its ironware at high temperatures to decarbonize the surface and prepare it for treatment against corrosion. The foundry takes extra care at this point, seasoning each piece with oil that has been mixed with nontoxic bamboo ash to yield a lustrous finish. These distinguishing features of its manufacture not only make the ironware rust-resistant, but also allow oils to permeate well into the cookware’s surface. The absence of Teflon or other synthetic coatings improves heat capacity, thus delivering the higher temperatures required by professional chefs directly to the ingredients. Meat and fish fry to crispy perfection, and no artificial coating means there are no worries about harmful substances leaching out at higher temperatures.
The beautiful finish of the Chef series and other Oigen products has an allure of its own, quite apart from the appeal of mirror-finish stainless steel or shiny copper. Because it is sand-cast, the ironware exhibits on its surface the grainy texture of the molds in which it is formed. Yielding an evenly textured surface is exacting work, as there is no room for correction by polishing or coating.
Oigen president Kuniko Oikawa explains. “When molten iron is poured into a mold, dissolved gases must be released that would otherwise cause surface imperfections or reduce durability. Typically, foundries will use rough-grained sand casings to ensure that the gases are emitted, but the larger particles result in a rougher surface. One of the hallmarks of Nanbu ironware is its smooth finish. That’s a direct result of the fine-grained sand casings we use. The downside, of course, is that there’s a higher defective rate.” In other words, pieces that pass muster elsewhere would not make the grade here. This insistence on form as well
as function testifies to the high quality of ironware that bears the Oigen name. When the foundry furnace is lit some two tons of iron are smelted per hour, which explains why the workers move through each step of the many production processes briskly and efficiently. Mixed in with the mainstay of pig iron are recycled iron as well as various coupling agents to maintain consistent quality. Adjustments at the smelting stage are also made based on ambient temperature, humidity, and even the external wind factor, all of which demand fine-tuning that derives only from years of seasoned practice. Deft skill and intense focus are also required when pouring the liquid metal, a task that affects the final strength and finish of each piece. The high quality of Oigen’s ironware reflects this dedication to craft and tradition—a standard that can’t be matched by lesser imitations.
Foundry coke fuels the cylindrical furnace, or cupola, that smelts the iron ore. Molten iron sends up sparks as it is transferred into spouted vats for transport to an electric furnace where it is kept hot. Meanwhile, workers steadily pour the liquid metal into sand molds for casting.