In his Artnews review of Jack Youngerman’s first New York solo show, at Betty Parsons Gallery in 1958, the poet and critic James Schuyler wrote of the paintings that “the images they suggest are like the illusions in clouds that no two people can both see or agree upon.” Such pictorial ambiguity requires considerable finesse, a quality the artist, now 83, brought to the eight hefty oil-on-wood paintings seen in “Triads/Quadrads.” Commentators have detected tribal, heraldic and even sexual imagery in these shaped, symmetrical works, in which stripes or bars radiate from (or thrust inward toward) a cloistered nucleus. Indeed, Youngerman’s way with flat areas of unequivocal color laid down with a firm, unshowy hand remains remarkably potent.

Notwithstanding their iconographic allusiveness, these paintings are most interesting for their evocation of an elastic space—a sense of simultaneous expansion and compression—within a static, emblematic format. Centrum (69½ by 69½ inches; all works 2008) centers four shattered squares in red and black on a little eight-pointed yellow shape, a Pop explosion. Quatrefoil Blue (72 by 72 inches) derives its retinal snap from the play of refracted and reflected light: a transparent ultramarine ground underlies opaque, undulating yellow bands. Reminiscent of Youngerman’s earlier organic imagery, the painting’s guts ebb outward—up and down, left and right—as if squished between four encroaching wedges.

Less figurative, Triarchia (59 by 60 inches) is a compound of two distinct color environments, an enantiomorphic crystal in the shape of the Jewish star in which nested chevrons in cerulean, grass green and orange-red adorn an inverted triangle of elongated vectors in yellow and black. Inverted triangles, including a jagged-edged one of raw wood, also appear in Serratus (57 by 60 inches) at the core of a trefoil shape the lobes of which trumpet red, yellow and blue. On plywood panels 13⁄4 inches thick, these paintings are dead flat but have a massive, sculptural presence. As such they proceed from the shaped wood reliefs Youngerman has made and shown during the past decade.

Roundabout (60 inches in diameter) is a simple tondo but its palette is downright circusy. At its core, a quartet of diamonds in cobalt blue, cadmium red and a zippy yellow-orange point north, south, east and west. A surrounding sunburst motif, a pleated-looking, two-tone zone of yellow and black, mimics its acute angles. Between this area’s zigzag boundary and the edge of the plywood support alternate two close reds, softening the tondo’s perimeter, providing a third color chord, and negotiating the transition from interior to exterior and foreground to background. The painting’s complexity is both kaleidoscopic and gyroscopic.

Ten small works on paper that appeared to be studies, in gouache, colored pencil or watercolor, attested that the seeds of this artist’s late, great style were sown as long ago as the 1960s. His is the freedom earned through rigor, and through the mastery of deceptively simple pictorial weights and measures.

Photo: Jack Youngerman: Triarchia, 2008, oil on wood, 59 by 60 inches; at Joan Washburn.