This year marks the 20th anniversary of George Hemphill’s gallery, Hemphill Fine Arts. And it’s been two decades since Steven Cushner stopped making rounded-edge canvases. Those two histories overlap in “Steven Cushner: The Shaped Paintings, 1991-1993,” a Hemphill show that doesn’t seem backward-gazing. That might be because only one of the eight paintings (which are joined by two drawings) has ever been exhibited before. But it’s also because Cushner’s early-’90s work has a vigor that hasn’t dissipated.

Mostly executed in black or blue-black on white, the pictures use motifs — orbs, arcs, crescents — that lend themselves to curvilinear formats. Although there are some solid areas, Cushner more often defines forms with multiple, roughly parallel lines. This might sound rigidly geometric, and the D.C. painter does cite the influence of Frank Stella’s austere, late-’50s pinstripe compositions. But Cushner lets the diluted acrylic pigment drip, which provides both spontaneity and a vertical contrast to the lines, whose orientation tends toward the horizontal. In addition, he paints the basic design, paints over it and then paints it again, adding grit and depth.

Where Cushner’s recent drawings and paintings are colorful, these pictures are mostly monochromatic; only “Bola” indulges in red, and then as a solo act. Yet the paintings do suggest the Washington Color School, both in their exaltation of the drip and their editing of images. Like Morris Louis, Cushner would paint first and format later; the canvases were trimmed and framed into ovoid shapes to complement their bowed lines. These days, the artist works within rectangular formats but is still drawn to curvy figures. If these paintings were a detour, they didn’t take Cushner very far out of his way.