Bosch und Siemens Hausgeräte GmbH (BSH) is on a mission to increase the use of induction cooking throughout Europe and the United States. To achieve this aim, the company needs to do two things: make its induction cooktops stand out from their radiant counterparts and entice consumers to absorb the increased cost of an emerging technology. To help meet these goals, the Munich, Germany–based OEM called upon Schott HomeTech (Mainz, Germany), its long-time supplier of glass ceramic.

The result was Ceran Cleartrans, a glass ceramic that offers industrial design options not possible with Schott’s standard monochrome black or white glass ceramics. Cleartrans has a transparent glass ceramic base decorated on both the top and underside. The topside
pattern is made from colored glass ceramic, while the underside is coated with a homogenous metallic film. This metallic coating is a thin composite of noble metals, including gold and platinum. The film, combined with the colored glass-ceramic topside pattern, provides myriad design possibilities, enhancing the aesthetic appeal of the cooktop.

A further design advantage of the material is that it allows for sophisticated user interfaces. A black semitransparent display area enables the use of different display colors and opens the door for complex display and electronics possibilities in future applications.

For product innovation manager Lutz Klippe of Schott HomeTech, bringing this product to market was not without challenges. The greatest challenge, he says, was meeting high-temperature stability demand while maintaining aesthetic quality and mechanical integrity. The key to the product, Klippe says, is the noble-metal underside coating. It does not compromise the durability of the glass ceramic even at peak hob temperatures, which can reach 500° to 600°C. “We had to develop something that was very heat resistant, very stable, that wouldn’t show any aging effects, even after long-time cooking applications. And on the other hand, the coating could not spoil the mechanical toughness of the glass-ceramic base material. This is not easy to achieve.”

As markets around the world warm up to induction cooking, Schott intends to create a small Cleartrans product that will be compatible with radiant cooktops as well. And of the design opportunities afforded by the new product, Rudolf Walfort, vice president, product development and management at Electric Cookers, BSH, remarks, “The superior­ity of induction  technology in terms of  speed and efficiency is extremely high. And with Ceran Cleartrans we can now make this technology more visible.”