By MADELEINE BAIR

No matter the type of artwork, audiences generally come to a gallery with one simple expectation: The art is complete. Artists at work and audience, convention dictates, do not belong together.

But at the Mission Cultural Center on Saturday night, tradition was thrown out the door as 77 artists and hundreds of guests filled the two large galleries to participate in an inclusive orgy of creation and observation.

Guests brought their curiosity and cameras. Artists brought their supplies. Blank white paper covered the 4,600 square feet of gallery surface. And in the span of four hours, art emerged.

“It is the moment of the creative process,” said Adrián Arias, an artist, poet and curator of Illusion. “The show is all about the spontaneity, the improvisation, and the ephemeral.”

After a procession up and down the block of Mission Street between 24th and 25th Streets, poets, painters, dancers and musicians, all wearing white, dispersed throughout the two galleries, finding a wall, floor space, or an impromptu stage to work. Guests, wearing black, followed—observing, inquiring, and before long collaborating with the artists.

Rio Yanez, a 28-year-old graphic designer from the Mission District, and his father, collagist Rene Yanez, blanketed one wall with 64 colorful prints they brought. Each featured an image of a woman, her face painted as a skeleton, with a thought bubble. “What we’ve created are templates for artists to come and create images going along with the idea of illusion and dreams,” said the younger Yanez.

Dreams acted as the theme of the show, and like the father-son team, many artists created a framework for others to express their thoughts on that theme.

Poet Nina Serrano offered a poetry corner. On two facing walls she taped her own poems in English, and Arias’s poems in Spanish (Serrano is the official translator for Arias’s poetry), as models for others to add to the wall. “I say ‘read a poem, write a poem,’” said the 74-year-old Serrano. “They look a little shocked, and then I hand them a Post-It, and most of the time they write a poem.” As she spoke, a woman sat down with a Post-It Note and pen to add to the dozens of fluorescent papers dotting the two walls. “Thoughts may come and go,” one Post-It read. “But dreams come to stay.”

While some artists came to Illusion with a planned collaborative work, others arrived with nothing but supplies and a mind ripe for inspiration. With black and brown colors, 24-year-old Tania Padilla painted a woman with fiery eyes, curly hair, and limbs in motion. When she began the portrait, “there was flamenco dancing,” Padilla said. She tried to capture the dancer’s strength and movement

Padilla, a Mission resident, normally works as a puppeteer and printmaker. She said the ephemeral nature of Illusion offered a refreshing challenge. “To not worry about preconceiving my work,” said Padilla, “it’s a really honest and revealing process, one that I’m not normally open to.”

It was also a rare experience for Jose Antonio Galloso, who painted fragments of his unpublished poems on one wall. The writer left Peru for San Francisco six years ago, “to be alone to write,” he said. As he copied his poetry and created a collage of his photographs on Saturday, he enjoyed the interaction with those who walked up to ask about his work and shared how they also use photographs for inspiration.

Adrián Arias began Illusion to reveal the artistic process, something that usually takes place in solitude. He has organized the event annually for the past six years, he said, “with the idea to create a space between artist and audience.” After the event, all of the art created “goes straight to the recycle, because art is not only a matter of results, but it is about creative processes.”

This year will be Arias’s final Illusion. “Now it is time to have a different thing,” said Arias, adding that many friends have started their own Illusions in cities around the world.

Like many of the participants, Riaz Abdulla said he was sorry to see the event go. “I like to view it as kind of a refreshment for the soul,” said 35-year-old physics teacher, whose face bore smears of charcoal. “Sometimes we don’t give ourselves the luxury of playing as adults.”