After a Corcoran season that has brought us metal squares laid out on the floor (by Carl Andre) and rocks laid out on the floor (by Richard Long), gallery visitors are apt to suffer a bout of deja vu - and some confusion - upon viewing the 20-ton firebrick installations by ceramic artist John Mason now hugging the floors of the upper atrium.

Is the Corcoran, in the scheduling trying to make a point about all art-on-the-floor looking alike? Or are they trying to show, as they should, the range of expressive possibilities available in this seemingly repetitious milieu? If greater public understanding in their goal, the Corcoran must more effectively put shows like this into a larger historical, stylistic context - something they have often failed to do.

"You have to write about this? Good luck!" sputtered one gallery-goer who had taken the trouble to climb the stairs in the still only partially air-conditioned building, look hard at the new installation and read the paltry room label, only to find no indication of what Mason's three-gallery-long squiggle of blond firebrick was all about.

For which the Corcoran ought to be ashamed. A visitor deserves more curatorial elucidation than: "The firebricks were lent by the American Combustion Company," or "The exhibition was organized with the aid of a grant from the National Endowment for the Arts." What about the art?

The reaction was predictable and inevitable. "You mean the Endowment gave money for this? The frustrated visitor left shaking her head, fed up with new art and angry with the National Endowment.

Which is surely not what the Endowment, the Corcoran and the Hudson River Museum in Yonkers, N.Y., had in mind when they organized this show of works from Mason's "Hudson River Series," one of six Mason shows now opening sequentially in museums across the country. In each case he designed his minimal-looking environmental pieces to fit the specific spaces. When the whole project is completed, an elaborate illustrated catalogue will be produced by art historian Rosalind Krauss, a little too late to help current viewers.

John Mason, Nebrasks-born, is an artist of particular interest because he came to large, environmental sculpture by the unusual route of ceramics. Since the '50s in California, when he worked with Peter Voulkos - another potter-turned-sculptor-Mason has produced a significant body of work that has sought to erase the heavy line traditionally drawn between the "craft" of ceramics and the "high art" of sculpture. It is a line that has rarely been crossed since Luca della Robbia decorated the 15th-century churches of Florence with terra-cotta madonnas and saints.

Mason's work has always been related to current art. In the '50s he made abstract expressioist sculpture; in the '60s, primal, geometric forms. While preparing for a one-man show in Los Angeles in 1972, overwhelmed by the problems posed by making monumental works from hand-crafted modules, Mason decided to let his mind rather than his hand prevail, and began using commercially produced blong-beige-colored fire bricks, the sort used in the construction of kilns.

Since then, he has created several environmental works with this cool and pleasingly colored medium just varied enough to be interesting, and somehow appropriate to the landscape references he evokes.Mason's meandering "squiggle" clearly calls up the pleasure of a cool, flowing stream. The reductive geometry of his forms may be related superficially to the work of Carl Andre, but in spirit he is far more closely allied to the romanticism of Richard Long. The casual viewer would be hard put to know that simply by looking at this show.

The exhibition continues until Aug. 13, as does "The American Landscape Tradition," a historical survey of paintings from the Hudson River School to the present - almost. The paintings made an interesting prelude to Mason's landscape evocations, which represent a very different but equally valid aspect of late 20th-century American landscape-related art.

In the past few months, Jacob Kanlen has closed one show - a traveling version of his 1976 NCFA print retrospective at the University of Oregon - and opened three others: at Associated American Artists in New York, the New Gallery of Contemporary Art in Cleveland and, earlier this month, at the Lunn Gallery, 3243 P St., NW, where new paintings and monotypes are on view through July 5.

The new paintings at Lunn hold no surprises, bur rather represent a further ripening at Kainen's now characteristic iconic abstract style. The best paintings here, however, seem pegged to just the right combination of structure, lush color and visible brush-stroking, of which the tense and tenderly brooding "Dark Decision" and the deliciously colored the textured "Goodbye Rome II" are supreme examples.

Less affecting are the looser, seemingly offhand paintings entitled "Argosy III and IV" and, at the other extreme, "Observer XXX," which seems too tight. Just exactly in between is the swirling monotype "Password," which reasserts the complete mastery of this artist's hand.

Washington is a big print city; every knows that. But is the current state of printmaking here?

In an attempt to find out, dealer Jane Haslem recently invited area printmakers to submit to a juried show at her gallery. Master printmaker Rudy Pozzatti from the University of Indiana spent two days viewing the 800 works submitted. Several of the best were solicited from local dealers like Wolfe St., Bader, Touchstone and Fendrick. Pozzatti a gentle, patient admirer of fine craftsmanship, managed to cull out 86.

The show? One of the dreariest displays of Washington art on the record.

Could the current state of printmaking in Washington really be at such low ebb? Haslem, who frequently judges print shows, concedes sadly that the resulting show, "The Washington Printmakers," really does represent what's going on in printmaking here.

And how does Washington stack up against other printmaking centers throughout the country? "Not too well, I'm afraid," says Haslem. "The printmaking boom in general has fizzled, and though there are pockets of good artists making prints, there are zillions of lesser artists also cranking them out. We need to turn off the artists faucet in this country and turn on the collectors faucet!

It is difficult to draw any conclusions beyond the fact the here, as always, the real pros emerge on top, and hacks continue to hack away. The freshest new work by far seems to come from the Wolfe St. Gallery Group, most notably Priscilla Treacy and J. Portaluppi. Through July 9.

Brida Lazzarino's show, just opened at the Bader Galley, 2124 Pennsylvania Ave. NW, affords all the pleasures of a good snoop around a fascinating apartment while the owner is out of the room. Born in Palermo, now living in Washington, Lazzarino obviously keeps sketch pad and watercolors at the ready, putting her time to good use making joyful, whimsical views of her surroundings, from a bird's-eye perspective that transforms everything into patterns much like a flattened-out cardboard dollhouse. The results are intimate domestic scenes redolent of a happy life.

There is also a touch of wit and fantasy that lifts the work beyond mere illustration. In "Husband Correcting Proofs," husband and chair have become one. Elsewhere, human presence in the scene is merely hinted at with a disembodied leg at the edge of the page. In "Another Very Private Collection" the artist herself seems to be snooping around, observing every object, book and pattern in great detail and with obvious delight. This is work few could fail to enjoy. Through July 8.

Like thousands of others, artist Nathaniel Bunyon Knight has found the sharp geometries of the new National Gallery East Building a fascinating subject for his camera, while remaining loyal as well to the gentle curves of the older half of the Pope-Pei complex.

What he has done with his color photographs, however, is unusual. Selecting certain shots, he has printed them in multiples and pasted them side by side, some upside down, with the goal of discovering within these juxtapositions new patterns altogether, patterns that have nothing to do with the original subject matter.

When a strong handsome new pattern emergers, that work can be striking, as in the case of a piece dealing with trees, and another showing the detail of a rounded column. In the lesser works, the pleasures are limited to those of decoding the photographs. It is an interesting idea, of not yet wholly resolved, and will no doubt lead to other things, notably commissions for large wall murals, with which Knight has already begun to experiment.