Number 7, 1950 is one of about a dozen long, horizontal paintings that Pollock executed after 1947. Rather unusually, he prepared a rust orange ground for this canvas. It offsets the ribbons of color laid on top, allowing us to follow the order in which he built them up. The long, narrow proportions of the canvas oriented his movements: in a series of flings, he made the calligraphic black, white, and yellow splatters while moving from one end of the composition to the other. This distinguishes Number 7, 1950 from larger, squarer paintings that he worked from all four sides to generate webbed compositions that seem to lack definitive tops and bottoms.
from Jackson Pollock: A Collection Survey, 1934-1954, November 22, 2015–May 1, 2016