There’s a wall on 149th Street between Convent and Amsterdam that used to be gray. Now, it’s still gray, but it’s also purple, orange, green, and yellow. Last spring, the city applied a fresh coat of paint to cover the graffiti that had overtaken it, but community residents say it wasn’t long until taggers reclaimed the wall with cryptic, multicolored messages: bw7, mskz, and Janster.

Graffiti is a problem New York City has been battling for decades. Like a parent who cleans up after relentlessly messy children, city crews trail behind graffiti vandals in a never-ending cycle. The U.S. Department of Justice says graffiti contributes to declines in property value, reduced retail sales, and heightened fears of gang activity.

An amendment Mayor Mike Bloomberg signed earlier this month may make cleanup faster and more thorough.

In 2005, the City Council passed Graffiti Free NYC, which provides free paint and cleaning services and has cleaned 2.5 million square feet of graffiti so far this year, said the sponsor, Councilman Peter Vallone Jr.; however, the paperwork and permission process has hindered cleanup efforts.

The new amendment “shifts the burden from owners to the city,” Carole Post, the director of agency services in the mayor’s office, said at a City Council hearing in September. “Once graffiti is identified the city will send a notice to the property owner saying the city will clean it for free, but if the owner wants to opt out they can within 35 days,” Post said.

An upper Manhattan coalition, ACTION, argued that the amendment wasn’t enough. Spokesperson Gail Cohen said property owners should face stiffer penalties if they don’t let the city clean up their graffiti.

“Don’t baby people,” Cohen told the City Council. “We want a strong bill.”

ACTION insists that New York adopt the stricter measures that have enabled cities like Chicago and Seattle to virtually eradicate graffiti, Cohen said. Citing research by Graffiti Prevention Systems, which surveys graffiti sites in Los Angeles, Cohen said the new law should also mandate speed.

“Data shows that graffiti removed within 48 hours has the best chance of not being repeated,” Cohen said.

Councilman Erik Martin Dilan held a different position. “Homeowners who are vandalized are victims of a crime, and to turn around and punish them is unfair,” Dilan said.

The mayor’s office said it issued 389 notices of graffiti violation to property owners last year. The fees collected for violations help pay for city cleanup crews.

At the hearing Vallone said compromises were required to pass any law, but maintained the new bill was stricter than the original and would improve the city’s graffiti situation. The new law was enacted Oct. 7.

Another concern for uptown residents involves graffiti on landmarked buildings. One Hamilton Heights resident spent tens of thousands of dollars on new windows, iron gates, and stonework restored for an 1897 limestone townhouse he purchased in 2005, only to see the house spray painted by vandals a few months later.

“We were horrified,” said the homeowner, who asked not to be identified for fear of being targeted again. “And let me tell you, most of the neighbors were horrified, too.”

By law, the Landmarks Preservation Commission must review proposals for any exterior changes to historic buildings, including stone refinishing. So owners either trudge through the commission’s permit process to remove graffiti themselves, or allow their buildings to be painted over by the cleanup crews. The alternative is to let the graffiti remain.

“I called the free service and they asked what color to paint it,” the homeowner said. “But it’s limestone!”

Many Harlem homeowners don’t want to clean their graffiti, Cohen said, because they worry about being vandalized again.

Just like the wall on 149th Street.