Ian McMahon’s pillowy plaster sculpture to meet its delicate end

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Ian McMahon’s “Sojourn” at T+H Gallery.

When Ian McMahon's "Sojourn" at T+H Gallery closes on April 22, the artist will destroy his work. He has to. It's the only way he can get his giant sculpture out the door.

He spent 12 days building "Sojourn," his latest large-scale, materially fragile, time-limited work. He sealed together seven industrial-size plastic bags and inflated them, then coated their insides with a thin layer of sprayed plaster. Once the plaster (1,500 pounds of it!) dried, he peeled the plastic away with a hot knife. The result – a massive, pillowy structure – nearly fills the gallery space. It skims the ceiling, and balloons over the iron bars that hold it up.

McMahon has said that he thinks of his works as moments in time rather than sculptures. Indeed, he turns traditional notions of sculpture, and particularly monumental sculpture, on their head. At more than 10 feet high and nearly 20 feet long, this work has the size of a public art piece that withstands weather and time passing, but "Sojourn" is no immobile object on a pedestal.

It breathes, shifts, and settles. Since it was built, one corner has lifted off the floor. The plaster has cracked, and an errant visitor – an unmonitored toddler, say – could cause irreparable damage. McMahon built a sealed door into one end; when you peer through a hole in it, you can see light filtering through the plaster. That's how thin it is. Yet "Sojourn" is a behemoth straining against its scaffolding, a Pillsbury doughboy on steroids.

The gallery screens videos of the artist's earlier works in another room: He takes down giant curtains of plaster with the quick swoop of a metal bar tethered to the ceiling. It's thrilling to see something so imposing crumble so quickly. The idea that a big sculpture in a commercial gallery is too delicate to last prompts a similar thrill; it can't be sold (T+H instead offers prints depicting "Sojourn"). The sculpture hums with the transient, unpredictable, hard-to-commodify energy of performance art.

Sadly, unlike McMahon's destruction of his curtains, the end of "Sojourn" won't be a public performance – space and safety considerations won't allow it. All the more reason to see it before it goes.

Photos like paintings

Nathan Miner's paintings at Rafius Fane Gallery are also big, and although more permanent than McMahon's sculpture, they feel fleeting.

Miner starts with an image – it can be as simple as a tile floor – then he plays with it digitally and by hand. He layers, he riffs; he skews perspective. The tile floor morphs into a 3-D matrix manifesting wisps and jets of color. In time, he projects his now abstract image on a large canvas, upon which he plays with watercolor pencil, water, and airbrush before he finishes with oil paint.

The result, in "Field Reflections #2," could be a picture of time's rush. The matrix shimmers and dodges, and at the center, colors explode and intensify. The structure, flash, and heightened tones make you feel you're witnessing a cosmic big bang, but the hallucinogenic blur somehow makes it more personal, as if the artist is toying with your perceptions.

Miner makes the viewer's space seem confluent with the painting's space using shaped canvases and 3-D works. "Jewel" was originally inspired by his idea, as a kid, to make a camera that could shoot in the round. He eventually did just that, and "Jewel," a 32-sided geodesic sphere, started with photos he took of a street in Brooklyn.

As with "Field Reflection #2," space bends. A melting sidewalk can be chased from one facet of this "Jewel" to the next, but it yet may vanish. The yellow sky knits together with the streetlights and buildings. The work becomes a picture of memory, slippery, engulfing, and infused with feeling. Utterly intangible – rather like shifting images in a crystal ball.

Scratching the surface

Israeli artist and architect Avner Sher scratches, scorches, and gouges the surfaces of used corkboards in his show at Clark Gallery. They read like palimpsests, embedded with messages, covered over and eroded. His scratched imagery often grapples with power. Whether that power is political, parental, or the wrath of an unpredictable god is left to the viewer to reckon.

Tiny troopers frequently show up in the shadow of looming figures. In "The Queen," Sher fills his surface with an eight-winged insect. Rows of miniscule insects cross the queen's body and set up in soldierly rows at her tail. On its face, this could be a metaphoric portrayal of the female/male dynamic among certain insects. The queen rules; male drones serve her.

"The Feast" takes us down a dark road. The head of a multi-eyed crocodile, mouth open, looms over zig-zagging tunnels below – the critter's saw-toothed mouth and gullet. Fish parade down the tunnels to their end. In "Life Is Just a Game (after Benigni)," rows of serpents are inhabited by railcars, suggesting the Holocaust's human cargo shipped to concentration camps.

Sher's questions about justice and clout read as age-old allegories, written on worn out templates, to which there have never been answers.

Ian McMahon: Sojourn

At: T+H Gallery, 460 Harrison Ave., through April 22. 401-390-1033, www.tandhgallery.com

Nathan Miner: Decade

At: Rafius Fane Gallery, 460 Harrison Ave., through April 22. 508-843-2184, www.rafiusfanegallery.com

Avner Sher: Scratching the Surface

At: Clark Gallery, 145 Lincoln Road, Lincoln, through April 23. 781-259-8303, www.clarkgallery.com