Black must play with light. The greater or lesser intensity of Soulages's black is obtained by the thickness of the paint layer. More or less translucent bars ensure the transition between the thick strength of the absolute black and the light. The expressive effect is similar to the color transitions on the edges of Rothko's rectangles.
The fundamental use of black by Soulages comes in the following of Franz Kline. Soulages replaces Kline's impulsive line by positioning his black with a wide squeegee in a carefully controlled geometry.
On February 9 in London, Phillips sells an oil on canvas titled Peinture 162 x 130 cm - 14 Avril 1962, displaying a structured composition in a beautiful oblique. It is estimated £ 2.5M, lot 26. I invite you to watch the video shared by the auction house.