Indelible Drawings Carved in Concrete

Precast concrete is one of the most durable and economical building materials, can be expressed in unique and artful applications. The offices of Foster + Partners architects embraced an intriguing process innovation in a precast application in Fortaleza Hall at the newest addition to the Johnson Wax company headquarters in Racine, Wisc. The new building was built to commemorate the family’s journeys to Fortaleza, Brazil. Like a theater-in- the-round, it features a magnificent circular glass façade and roof rising two stories above a below-grade, conical reception hall with wooden mosaic floors and precast concrete walls. The precast walls feature a subtle grayscale mural of a Brazilian palm forest to represent a canopy of trees over which a replica S-38 amphibian airplane soars. The rasterized image imprinted on the precast was reproduced from an original photograph taken on H.F. Johnson Jr.’s 1935 journey, using a process developed by Scandinavian fabricator, Graphic Concrete, Samuli Naamanka, in Helsinki, Finland. The process combines alternating swaths of exposed aggregate with fair face of the precast to register the desired pattern or image. The graphic concrete process that uses a custom image is dubbed GCArt. The process begins with a scaled image transferred onto a membrane that is then placed in a mold for prefabricated cast concrete. After 24 hours, the membrane is peeled away, and the surface cement that has not set is washed away to reveal an indelible image in concrete.