Judd began making stacks in the 1960s. Most consist of ten elements, although there is variation in the materials used. The stacks are all ordered according to strict principles: the gap between each unit, and between the first unit and the floor, should be equal to the height of a single unit. Since the units are all identical, their significance derives from this pre-determined geometric order rather than from any individual features. However, Judd's attention to the sensuous qualities of his materials prevents Untitled from being cold or clinical.