Painting a mural is not like painting a picture on canvas and then hanging it on the wall of a gallery. The kind of painter who creates museum pieces doesn't usually have to worry about the effects of sun and rain, for instance, or about the work being painted over or defaced with graffiti - much less being hit by a truck.

But one day last week, walking past the colorful works of art that cover nearly every wall in the Mission District's Balmy Alley, Precita Eyes Muralists founding director Susan Cervantes pointed out one of her murals that had fallen victim to just such an accident.

A large garage door and its surrounding wall had first been painted in the 1980s, but some years later a driver smashed through it. Once a new door was in place, Cervantes painted a completely new design and blended it in with the surviving parts of the original work. The result, "Indigenous Eyes: War or Peace," is one of the most striking and popular murals on the alley.

"It's a continuous event, because it's always changing," Cervantes said. "Not that you see so much changing on other murals, on other buildings, but for the alley, it's always been something that changed."

Cervantes has seen just about all of that change close up. Precita Eyes Muralists, the organization she founded with her late husband, Luis Cervantes, is celebrating its 30th anniversary Saturday with a gala affair. In those 30 years, Precita Eyes - one of just five community mural groups in the nation - has helped put together more than 450 murals on schools, parks, businesses, private residences, even a series of utility boxes.

Beyond that, Cervantes has tended to the flowering of a mural art movement not just in Balmy Alley, not just in the Mission and the Bay Area, but all over the world.

Cervantes, who was born in Dallas, came to San Francisco in 1961 armed with a scholarship to study at the San Francisco Art Institute. (She notes that the school's now-famous Diego Rivera mural was draped at the time because the administration thought it was old-fashioned.) After she met Luis, himself a well-known muralist, they raised a family together in the Precita Park neighborhood. When her children were young, she began looking for ways to get involved in her community and brighten up her neighborhood. This eventually led her to join the arts group Mujeres Muralistas, and ultimately to start Precita Eyes.

Today, the group, in addition to organizing dozens of mural projects, runs a small art supply store, holds walking tours and teaches classes. Last week, behind the art store there was a large plan for a mural under way in one room, while another room was decorated with wall-size paintings of great muralists who have passed on. Cervantes knew them all.

"When we started the organization, maybe at that time I was managing three projects a year," Cervantes said. "Now I'm managing maybe 30."

Some of these works are the familiar Latin American images of oppressed farmers and raised fists - images of "the struggle," as Cervantes calls them - but an increasing number are something completely new, inspired by cartoons and hip-hop and surrealism. Some things haven't changed, though. Noting the lack of up-to-date computers, she said: "We pretty much stick with pencil and paper and paint."

Clearly, that isn't slowing her down. This past spring, Cervantes went to China to teach people in the still nominally communist nation how to paint together communally. "They had no concept of community art," she said. "They were afraid to touch each others' drawings. Or even to paint in someone else's design. But once they got into it, and everyone else came up to them to help, they learned to let go. That's part of the process even here, is learning to let go, giving this gift to your whole community."

"Community" is a word that comes up often when Cervantes talks. And when she says it, she doesn't sound like a politician. When she says mural art is "art that's for the people, by the people," she's not just speaking in platitudes.

Precita Eyes' projects may be shepherded by an experienced artist, but ordinary people are doing much of the planning and painting. "It's what makes the difference between what we do and what other people may do," she said, "or what has happened in the past. Originally, that's what mural art was about. If you think about going back thousands of years to the cave paintings, it really was a community thing for spiritual, ritual or educational purposes."

That kind of spirit shines through in some unexpected ways. Cervantes points out that while the few plain walls in Balmy Alley are covered with graffiti tags, the murals are rarely touched. People in the community are less likely to damage the art because "they've been involved in the process," she said.

And even the notorious inflation of San Francisco real estate prices has done surprisingly little to slow the growth of murals. When pressed, Cervantes noted that a recent project at a school in Noe Valley was stopped by neighbors anxious about their property values, but she said she only rarely encounters that kind of resistance. Indeed, she said, many property owners see murals as an asset.

Homeowner Richard Purcell agrees. "Oh my God, yes," he said. In 1993, he was looking for a new home for himself and the AIDS nonprofit Aurora Dawn Foundation, which he runs out of his house. "I had looked at about 100 different places," he said. "The minute I saw this place, I said, 'This is it.' "

The place is the site of the "Indigenous Eyes" mural. "A lot of people know Balmy Alley," he said, "a lot of people in San Francisco, but also from all over. A lot of the visitors we get in the alley are from other countries. If we ever come to the point where we have to sell it," the mural is "definitely a selling point."

Purcell was so enamored of the mural that he ended up joining Precita Eyes to help paint its dozens of murals at the Alemany Farmers' Market. Eventually he served the organization as a member of its board of directors for nearly 10 years. "It's just barely keeping its nose above water in terms of funding," he said, "but it's great for community building."

The life of a muralist is a hard one. You can't sell a mural the way you can sell a canvas. Grants and compensation for the work are hard to come by, and often there's more in the budget for materials than for the artists. "Our time was sometimes not equal to a bucket of paint," Cervantes said. "Not a good way to make a living."

Cash flow is always a concern, but it's clear that for Cervantes, the rewards outweigh the headaches. "We want to keep it going another 30 years," she said.

Precita Eyes celebrates its 30th anniversary with a gala benefit featuring live mural painting, live music, refreshments and a silent auction of art donated by master muralists. $30. 6-10 p.m. Saturday. Project Artaud, 450 Florida St. Call (415) 285-2287 or go to for tickets and information.