Untitled B belongs to a small group of Veil and Floral paintings created by Morris Louis in 1954; by June of that year his work had changed direction and he did not return to explore the great potential of these paintings until 1958. Although he had considered himself a professional artist from the 1930s when he completed art school, nothing in his work prior to these paintings of 1954 suggests their potential, subtleties or originality.

These were the first paintings in which he began to explore the possibilities of his newly developed staining technique. He worked exclusively with Magna acrylic paint and thinned it extensively with acrylic medium. In the case of Untitled B, he poured many different colors from the outer edges of his canvas across the field. Colors soaked into the canvas and into each other, yielding a hovering atmospheric mass. The active silhouettes of the outer edges of each pour create a dynamic draftsmanship.

The combined effects of delicacy of color and spatial expansiveness indicate a profound understanding of Jackson Pollock, whose work had deeply impressed Louis. In addition, his 1954 stain paintings like Untitled B were the first works in which Louis found a personal vocabulary that took into account the techniques of Helen Frankenthaler which had also inspired him on a visit to New York the previous year.