By Judith Wilson,
"Edward Clark: Directions", Art in America, January 1981.

...France inspired more expansive lateral motion than ever before. This eventually gave rise to a series of oval-shaped canvases, starting with the Big Egg in 1969.

Streaked with horizontal bands of orange, pink and blue, it maintains some of the splashed and splattered exuberance of his earlier Action Painting. In subsequent shaped canvases, though, Clark eliminates these gestural effusions, increasing the tension between his pushbroom's horizontal path and his support's elliptical shape...

In Purple Stretch, Clark achieves a more ambiguous space by allowing the painting's edge to crop the oval laterally and unifying the figure and ground chromatically. Both paintings have a speeding central band of rhythmically modulated hues. But the play of color against space is more active in Purple Stretch because its figure/ground relationship is more elusive.