REDMOND — The downside of a haunted house gig is the makeup, according to Megan Shaw.

Shaw closed her eyes tightly as Mike Yruegas worked his way around her in a darkened room, applying quick bursts of fluorescent paint to her face with an airbrush. Every night she’s gone home after several hours of terrifying visitors to Redmond’s “ScareGrounds,” Shaw’s been exhausted — but before she can collapse into bed, she’s due for a long, hot and vigorous shower to scrub the paint from her face and hair.

The upside is, well, obvious.

“Last week, there was this kid who was like, 13, and I scared him so bad that he backed himself into a corner and his 3-D glasses fell off,” said Shaw, 19, from Bend. “It was great!”

Now in its eighth year, The ScareGrounds has been up and running in the old Parr Lumber warehouse in downtown Redmond every Friday and Saturday for the last four weekends, and has three final performances coming up this week on Wednesday, Thursday and Friday. Run by Jim and Sheri Stirewalt, the event serves as a fundraiser for the Oregon Athletic and Educational Foundation.

Putting on the show is a massive undertaking, involving several tons of set materials, props and costumes, and 70 to 80 actors and other volunteers on any given night.

Actors have been recruited largely by word of mouth, Sheri Stirewalt said, most of them coming from local high schools.

Yruegas has been doing makeup and set design work for the ScareGrounds for the last four years.

Working in an unlit room save for a few blacklights, Yruegas described how with the addition of special glasses issued to haunted house visitors, red painted items appear to move closer to the viewer and blues farther away, creating a disorienting, 3-D effect.

Spraying a bat-like pattern on a new actor’s eyes, Yruegas said he’s free to be as creative as he likes in his work for the ScareGrounds.

“I try to do them all different, make a different kind of scare,” he said. “There’s some people that might be scared of spiders, some people might be scared of rats, clowns.”

Moving through a warren of plywood walls separating the haunts from the backstage area, Jim Stirewalt is checking to see that everything is plugged in and in place for the crowd gathering outside the warehouse. Pushing open a door to poke his head inside one of the rooms where guests and actors will be meeting in less than half an hour, he explained that such “chicken doors” are an essential part of the haunted house business.

“Because we’ll have people who want to get out, and get out now,” he said.

Under such circumstances, the actors will break character, Stirewalt said, and the machete-wielding clown or straightjacketed mental patient that moments earlier was seeking to frighten will calmly escort the stricken to the exits. Many do get frightened, he said, and at times, they’ve had nights where up to a third of their visitors have ducked out a side door rather than continue their way through the haunts.

Shawna Vandeberg said she was lured in to the ScareGrounds by her son, a Redmond High School student and an actor in the production. Vandeberg does face painting professionally, but as she’s “usually doing children’s festivals,” she doesn’t often get the opportunity to work.

“It’s a change of pace, but it’s been a ton of fun,” she said.

Elmer Chavez, 21, of Redmond, is in his fifth year volunteering at the ScareGrounds. Waving a hairdryer across his face to help speed the drying of the latex that’s been painted on his face, Chavez said he had a role as a clown in his first year but has since been promoted to serve as one of the “core actors,” this year as a deranged and badly scarred janitor.

The janitor is a good role, Chavez said, though he admitted he hasn’t found much to do with the character beyond tripping over his mop bucket and loudly grunting at people.

“I like being a clown, but I’ll do anything, depending on the theme,” he said. “As long as I get a good scare, man.”