For the first time in 20 years, the Pike Place Market gum wall will get a major scrub, market staff said.

The steam cleaning of the wall and adjacent walls in Post Alley will begin at 8 a.m. Nov. 10 and is anticipated to last until Thursday, November 12 or November 13 due to its multi-ton volume, staff said.

“The gum will be allowed back within the boundary of the original wall, which is left (north) of the Market Theater,” market spokeswoman Emily Crawford said.

The gum wall was started 20 years ago by audience members waiting in line for our late night improv show.

“Since then, it has been cleaned and recreated three times,” said Kent Whipple, Marketing and Development Director for Unexpected Productions, the improv theater troupe that operates the Market Theater in Post Alley. “The Wall is like the art that takes place behind it, constantly changing from the sharing of its participants. And, like a good improv story, has a beginning, middle and end. The Wall is ready to start a new story. We are excited to see the new incarnation.”

The Market also is hosting a photo contest celebrating the Gum Wall, which has more than 80,000 tagged posts on Instagram.

“We recognize the Gum Wall is one of the most photographed locations at Pike Place Market,” said Crawford, who is Director of Communications and Marketing for Pike Place Market Preservation and Development Authority. “The photo contest provides an opportunity for fans around the world to share their Gum Wall memories.”

For people who want to stick one last piece of gum on the wall before it is cleaned, the Gum Wall photo contest runs from Tuesday, November 3 to Monday November 9, 2015. Voting ends on Thursday, November 12, 2015 with the winner announced the next day.

Photos can be posted to the Pike Place Market Facebook page or the contest web page.