Jacob Kainen is art history in Washington. Or at least, postwar contemporary art history. Curator, teacher, writer and, above all, artist, he brought abstract expressionism to Washington in the early '40s and promoted printmaking in his position as a graphic arts curator at the Smithsonian Institution.

Kainen and the Washington color school are inseparable: He worked with Ken Noland, promoted Morris Louis and taught Gene Davis and Alma Thomas. Since his early years in New York, Kainen's work has long been identified with abstract expressionism. It's the spiritual side of the movement; painting as a cathedral in which we meditate upon Clyfford Still's magisterial peaks or Mark Rothko's solemn hues. But Kainen is often more emotional than Rothko, and more playful than Still. He is not a formalist; although color, luminous and ambiguous, shifting and changing with the light, is a large part of his reputation, a Kainen painting is not about color for color's sake.

Kainen is a romantic and has been since his earliest figurative work, which he describes as being about "fires, flood and ships sinking at sea." Decades later, his abstract work has focused on his origins, both his early New York art influences and his Russian heritage. In his new paintings at the Middendorf Gallery, the "Dabrowsky" series refers to the Russian name of Joseph Graham, a New York painter who was a "Magus" figure for Kainen. Kainen also calls the colors in this painting "Russian . . . more oriental, not hedonistic like French color." His forms, with their "weight of associations," perhaps have Russian connotations too; there is a recurring lattice-shape that could just as easily be a Russian Orthodox cross.

The "Dabrowsky" series -- painted since last fall, as were most of the large abstractions in the show -- doesn't represent Kainen's best work. Nor for that matter, do the other four paintings on display. The Kainen hallmarks are all visible: the serial work, surprising colors, the often playful forms (stars? birds?). But there's a weariness here, a missing rigor, an absence of the dynamic. These are not like the paintings of a decade or two past that Gene Davis called "bold, even arrogant." Earlier Kainens have a dislocative quality to the relationships between figure and ground that is as exhilarating as it is unsettling.

Kainen says he is after a "serene quality . . . an agitated serenity." The problem is that the agitation is missing; the work is more becalmed than serene. Despite the containment of the canvas rectangles, the forms in these paintings float away like fish in an aquarium window. There's no center to the work; no axis; no point of equilibrium. Forms, spaces and colors refuse to coalesce into an experience; they float into sight, then all too soon out of mind.

Barbara Ess, a young New York photographer, is showing work in Middendorf's top-floor gallery. Once past a rather heavy veneer of chic, there is much to like in her large, monochromatic pinhole photographs, which have a new-wave cinematic feeling akin to "Diva" or "Liquid Sky."

These are black-and-white negatives printed on large sheets of color photo paper. The results -- in bilious greens and flaming scarlets -- are skies streaming with clouds, and empty cities, possibly postapocalyptic, in which it always seems to be dawn. There are dogs with legs like trees, dolls and cows joined in an unlikely partnership and people numb with angst.

Ess' work, attractive despite its painterly mannerisms, seems a series of fitful glimpses uncertain whether to become a serious vision or a music video. I look forward to seeing more of her work if only to discover the crossroad she's taken.

The Kainen and Ess exhibitions close May 10. The Middendorf Gallery is at 2009 Columbia Road NW; hours are 11 a.m. to 6 p.m. Tuesdays through Fridays, 11 a.m. to 5 p.m. Saturdays. WPA's 'Cryptic Languages'

Currently at the Washington Project for the Arts is a group show of installations and videos devoted to a frequently political examination of the way artists (and by extension, societies) use words.

"Cryptic Languages," on view until May 17, is exactly that: a cryptic, sometimes arcane, but frequently diverting examination of language as sign, symbol, gesture and hieroglyph.

New York artist Kay Hines is both serious and entertaining with her witty machines that weave together endless loops of diverse writings, and to be in the room occupied by Washington artist Henry Chotkowski is to be inside the head of a metaphysical detective as he seeks to unravel the mysteries of the attempted assassination of President Reagan. His conclusions -- thought-provoking, recondite and original -- will surprise you, but then they probably surprised Henry Chotkowski, too.

The WPA, 400 Seventh St. NW, is open 11 a.m. to 5 p.m. Tuesdays through Saturdays, to 7 p.m. Thursdays.