SEATTLE — It took 10 minutes and a patented spray-washing method to give the city of Seattle hope that a beloved neighborhood mural its maintenance workers accidentally painted over can be saved.

On Thursday, the much-missed colors of the mural in the Phinney Ridge neighborhood emerged from the drab, gray paint after a crew from Bellevue-based Surface Cleaning Technologies used a fairly new method of spray washing that combines low-pressure spray, warm water and volcanic crystals the size of fine sand.

The result was a 24-square-foot patch that showed some signs of the friendly paintings of giant animals that once had decorated this underpass near the Woodland Park Zoo.

The city gave the Bellevue company permission to try out the new method of spray-washing on the underpass, but now it’s up to the city to decide if it wants to spend the money to finish the job.

The spray washing is also a way out for the city of an embarrassing dilemma that started a few months ago.

In March, Phinney Ridge resident Greg Zuhl called the city’s graffiti hot line to report a few tags sprayed on the mural, which was completed by a group of neighbors in 1994 as part of an arts campaign.

Zuhl noticed nothing was being done about the spraying, so he called the graffiti hot line three times. He also called the zoo, which then called the hot line twice.

All those calls made it seem to the city as if many neighbors were complaining.

So the city sent in its Graffiti Rangers, a six-person crew that removes graffiti. The 50-foot-wide artwork was then painted over.

Pete Hall, general manager of Surface Cleaning Technologies, guessed it would cost between $5,000 and $10,000 to do the whole job. The original mural came from a $2,000 grant.

“If the price is reasonable and results are as expected, certainly it’s something we’d consider,” said Rick Sheridan, spokesman for the city’s Department of Transportation.

Zuhl was one of the onlookers Thursday while Hall and his low-pressure hose sprayed off the gray paint.

“Seeing the color come back just gives me an incredible feeling,” he said.