A former Bento stand in Kyoto has been transformed into a coffee kiosk for confectionery company Suetomi. The distinctive blue-green finish of the copper cladding was achieved through a rapid oxidation process using soy sauce and ammonium chloride. This vibrant color choice draws inspiration from "Suetomi blue," the company’s corporate color for over seventy years.

Located at the base of a two-storey wooden building on a busy intersection, the one-meter-deep kiosk serves as both a coffee stand and a signboard, guiding customers to Suetomi’s flagship store just three minutes away on foot. The design intention was for the stand to function as a signboard with its distinctive color, leading customers from the bustling street to the main store.

Inside, the kiosk features a kitchen and a takeout counter equipped with a sliding wooden hatch and a perforated metal screen. The front of the kiosk is clad in brown copper, while the side facing the intersection showcases the striking blue copper finish. A recessed area lined with blue copper includes a wooden bench for customers, adjacent to a concealed storage space.

The patina color is prominently displayed on the eye-catching side facing the intersection and in the seating area. Cityscape regulations typically govern facade colors, but the oxidation process was allowed as it was achieved through natural methods. The copper was first treated with soy sauce to create a darker, reddish-brown color, followed by ammonium chloride for the distinctive blue-green hue. Without these chemicals, the copper would have taken three months to develop a reddish-brown color and several years to achieve a blue finish.

At night, the seating area is enclosed with a blue mesh sheet typically used for scaffolding. When illuminated, it evokes traditional Japanese screens, allowing views of the patina color on the wall. This feature functions as a “street lamp” for pedestrians while also serving as a billboard for the store.