The defacement of the Sydney Opera House in Australia last month produced what most graffiti vandals want: notoriety. CNN and other news outlets ran stories on the anti-war message painted across the highest "sail."
But the incident was atypical because the graffiti was erased within a day by a crew using state-of-the-art blasters and chemical treatments.
In the US, undoing graffiti damage costs $10 billion a year, researchers say, and few cities can afford the gear to perform such quick cleanups.
But several young companies are selling new computer-based systems designed to thwart "taggers."
Traptec, in Escondido, Calif., is developing Taggertrap, which uses ultrasonic sensors to detect spray paint cans in use. When it picks up the release of compressed air and liquid, it sends a wireless alert to police.
The San Diego Police Department caught six taggers in a trial test of Taggertrap, says Sgt. Lee Norton, part of the city's new eight-person graffiti strike force, which hit the streets April 1.
"The graffiti problem is a lot larger than most people realize," says Sergeant Norton. San Diego has dangerous "tag-bangers," groups of vandals who mark their territory then pick fights with other taggers in the area, he says.
The city spends $1.2 million to $1.5 million a year to clean up graffiti, Norton says. The police rely mostly on old-fashioned stakeouts to catch the vandals, he says, but they do use digital cameras and databases to track suspects and incidents.
Q-Star Technology, in Chatsworth, Calif., sells another high-tech tool. The FlashCam-530 uses motion detectors, triggered if someone comes within 100 feet. Bright lights flash and an alarm sounds, warning suspects that their photos are being taken and the police alerted.
That's usually enough to scare them off, says Q-Star president Ken Anderson. About 100 cities, including Los Angeles, have bought the $2,995 units.
Public Technology, a Washington nonprofit, is working with Lawrence Livermore National Laboratory on a laser graffiti-removal system. At about $100,000 a unit, says Conni Kunzler, a spokeswoman for Graffiti Hurts, it's expensive. But it removes marks without damaging the structure or paint below, she adds.
If a tag is gone just 24 hours after it's painted, the tagger may lose motivation to try again. "The most effective deterrent," Ms. Kunzler says, "is rapid removal."