Newman often proclaimed Onement, I to be his artistic breakthrough. This is the first time that Newman has used a vertical line to define the spatial structure of his work. Newman later took this line, which he called a "zip" and made it his signature mark. Newman applied the light cadmium red zip atop a strick of masking tape with a pallet knife. This zip, while appearing to divide the composition in two, actually unites and merges the two sides together.