This refreshing first solo exhibition in London of the work of the American painter Leon Polk Smith, who died in 1996 at the age of ninety, not only afforded British audiences an opportunity to discover a pioneer of hard-edge painting but also offered a nuanced view of what’s possible in abstraction. Spanning the years 1966 to 1970, the show consisted of eight rarely exhibited, multipart shaped paintings (including five drawn from the artist’s “Constellation” series, 1965–73), and a large, freestanding doubled-sided screen.

The “Constellation” works are generally regarded as a high point in Smith’s oeuvre, and, as the title suggests, they consist of multiple parts that form a greater whole, but the three other modular works on view—all also painted in flat, bold colors—were equally compelling. Although geometric abstraction is often described as reductive, the eight paintings here showed how complex Smith’s constructions really were in this period. For instance, 6 Circular Modules, 1970, consisted of a sextet of tondos with each circle divided in half, into green and blue semicircles. Stacked in an ascending diagonal formation of two rows, they could also be considered a pair of trios. The lower group together created the image of a blue line running through a green field, while the upper group produced the opposite effect of a green line through blue. The result was a playful flickering of registers between image and object that also was seen in several other paintings.

Born in 1906 to part-Cherokee farmers in what was then Indian Territory and would later become Oklahoma, Smith described the wide-open spaces of the flat plains as where “one could see 250 miles in every direction . . . the sky seemed so big . . . almost like an endless space,” and this landscape had been a great influence on his work. That spatial feeling was transfigured in his paintings, where, in his words, form and space interchanged. The result was a quality of visual ambiguity, a vacillation between positive and negative, figure and ground.

Whereas other hard-edge painters prioritized a complete unified object or determined their exterior edge from the composition within, Smith used complexity to convey a sense of an exterior or of expansion. Particularly in the period covered by this show, each module in Smith’s work is relational and evocative rather than a self-contained entity. The parts of 6 Circular Modules, with its horizontal lines, collectively hint at a horizon or a flow. There is a sense that this is a cutout of a larger swath. Linear division was not Smith’s only drawing element. In Constellation Q, 1968, for instance, the edge defined and distinguishes form. Consisting of three different monochromatic elements—a blue tondo abutting two lozenge forms, a yellow vertical and a red horizontal, below it—this work could also suggest a graphic of a pointing figure. Yet, independent of this imagistic suggestion, shape and color create spatial distinctions, with the blue receding while the brighter red comes forward.

In retrospect, these works, all of which had curved corners, recalled design and graphics of the era; think of the Pan Am logo or Lance Wyman’s Mexico City subway icons, or even cathode-ray television screens. That period sensibility brought an unexpected resonance. And the absence of sharp corners suggested the boundlessness of the field of vision, thereby recalling the openness of the Western landscape that first inspired Smith’s sense of space. Far from reductive, his art is all the more evocative for its abstractness.

—Sherman Sam