In the 1950’s Enrico Castellani detached himself from informel painting. Having modified his paintings plastically by using mounted threads and vertical foldings of the canvas, around 1960 he changed to a construction of canvas reliefs with monochrome surfaces. The surface of the painting was lined and systematically structured by rows of nails. Those were placed either underneath the canvas to elevate or placed from the front to dent the surface. The unlimited proceedable rhythmical structure, which causes differing grids of light and shadow at the images surface, was further differentiated and varied by Castellani throughout the years. Like Lucio Fontana and Piero Manzoni he was part of the exhibitions of the group ZERO until 1965. Superficie bianca No° 18 [White surface] radicalizes Castellani’s idea of a painting as object. The rhythm of light and shadow, emptiness and volume articulates the imaginary border between sensuous presence and abstract ideality.