Pike Place Market's gum wall in Seattle, the world's second germiest tourist attraction, to be scrubbed of gum

Once named the world's second-germiest tourist attraction, Pike Place Market's gum wall in Seattle will soon be scrubbed of 20 years' buildup of sugary stickum.

Emily Crawford, a spokeswoman for the Pike Place Market Preservation & Development Authority (PDA) said the gum wall is cleaned "every other month" by the PDA with a steamer, but this will be the first time all the gum is removed from the original wall.

The PDA has hired a contractor, Cascadian Building Maintenance, "because it's going to be a very large job," Crawford said.

Kelly Foster, of Cascadian Building Maintenance, said the gum will be removed with an "industrial steam machine that works like a pressure washer."

The machine will melt the gum with 280-degree steam; it will fall the ground and a two- to three-man crew will collect the gum in five-gallon buckets.

"This is probably the weirdest job we've done," Foster said. Crawford said the PDA estimates about 1 million pieces of gum are adhered to the walls of Post Alley, in some places 6 inches thick. The job is expected to cost US$4,000 (NZ$6074).

More accurate figures on the amount of gum could be forthcoming. "We want to weigh it," she said.

Crawford said the gum needs to be cleaned off the walls to preserve the historic buildings in the Market district.

"It was never part of charter or the history of the Market to have the walls covered with gum," she said. "Gum is made of chemicals, sugar, additives. Things that aren't good for us. I can't imagine it's good for brick."