Newman proclaimed Onement, I to be his artistic breakthrough, giving the work an importance belied by its modest size. This is the first time the artist used a vertical band to define the spatial structure of his work. This band, later dubbed a "zip," became Newman's signature mark. The artist applied the light cadmium red zip atop a strip of masking tape with a palette knife. This thick, irregular band on the smooth field of Indian Red simultaneously divides and unites the composition.