'Green slime' may save homes from Wyoming fire

JACKSON, Wyoming (CNN) -- After five days of staving off a fire that has burned more than 3,100 acres and threatens to destroy several subdivisions, firefighters will cover some threatened areas with "green slime" to pre-empt the Green Knoll fire, officials said Friday.

"It is well worth being slimed to save your house," said Joan Anzelmo, spokeswoman for the Green Knoll firefighting effort.

The fire was 50 percent contained. A team of more than 1,000 firefighters -- which Anzelmo called one of the largest teams ever in the country -- continued their efforts Friday, trying to contain the rest of the blaze.

Two housing subdivisions in Wilson, Wyoming, six miles southwest of Jackson, remained under mandatory evacuation orders Friday. Residents may not be able to return to their homes permanently for two or more days, Anzelmo said.

She stressed that homes in Jackson are not threatened.

Firefighters were able to prevent the blaze from reaching the homes after it came within a half-mile from some structures Thursday.

"This morning, I can confirm that no homes have burned," Anzelmo said, "and we're hoping it stays that way."

Low humidity and wind gusts up to 30 miles per hour could blow the flames toward the homes Friday, Anzelmo said.

Some 11 helicopters dropped water on the blaze, while several fixed-wing aircraft released "slurry" -- a red-colored fire retardant -- on the fire.

The slurry is not as precise as the green slime, which fire officials will use to coat structures that are most at risk. The green slime does not cause any permanent damage to the buildings and can be hosed off with water after the fire has been contained.

The cause of the Green Knoll fire is still under investigation. Officials said it started Sunday in the Bridger-Teton National Park, just north of Jackson.

"It's unclear whether it was a lightning strike or whether it was a man-caused fire," Anzelmo said. "The fire is still too dangerous for the fire specialists to get in to determine what caused it."