Over the years there were changes to the process. In Opałka's first details he painted white numbers onto a black background. In 1968 he changed to a grey background 'because it's not a symbolic colour, nor an emotional one', and in 1972 he decided he would gradually lighten this grey background by adding 1 per cent more white to the ground with each passing detail. He expected to be painting virtually in white on white by the time he reached 7,777,777 (He did not use commas or number breaks in the works): 'My objective is to get up to the white on white and still be alive.' As of July 2004, he had reached 5.5 million. Adopting this rigorously serialized approach, Opałka aligned himself with other artists of the time who explored making art through systems and mathematics, like Daniel Buren, On Kawara, and Hanne Darboven. He was represented in Paris and New York by Yvon Lambert and in Venice by Galleria Michela Rizzo.