John Vlass of Marietta can’t find his nose.

There are only so many spots a red clown honker can hide. Yet his RV is in such disarray with clutter it could easily be covered by one of several piles.

As Vlass continues the hunt, it’s obvious his wife isn’t with bunking with him for the next several days. No feminine touch in sight. Vlass is flying solo, but not totally. He’s in one of approximately a dozen campers and RVs lining what he and his cohorts dub “clown alley” at Jim R. Miller Park in Marietta. It’s the site of the 70th Annual World’s Largest Shrine Circus & Midway Carnival.

Vlass, a second-generation Shriner, is one of the volunteer clowns performing during the circus’ run. Many of these guys, ranging from blue-collar types to retired business execs, call the fairgrounds home for the duration becoming instant celebrities in the process. Vlass, who owns an office furniture business, is not only donating his time to clowning, but he’s burning vacation days to boot. This gives him plenty of time to focus on becoming Opa, his alter ego.

Vlass recovers the nose, and now the morphing begins. The process usually takes 40 minutes to an hour. White greasepaint goes around his mouth and eyes; fleshy rouge covers the rest of his face; a red smile stretches across his lips and sweeps up above the corners of his mouth. After slipping on a green braided wig and capping it off with a yellow beanie, Opa officially arrives.

Although he refers to this yearly event as “a big boy’s camping trip,” this is all serious business to Vlass. He’s president of the Yaarab Red Devil Clowns, the oldest continually-operating Shrine clown group in the country.

The circus itself is the only fundraising event operated by the Atlanta-based Yaarab Shrine and proves to be a huge financial shot in the arm for its charity work. According to Chuck Pittman, circus director and the Yaarab Shrine’s Chief Rabban, the entire proceeds from the circus go to support the Shrine’s operating budget. This includes funding the transport of Atlanta-area children to Shriner’s Hospitals in Greenville, S.C. and Cincinnati, Ohio. In addition Pittman says the Yaarab Shrine contributes an average of $1 million annually to Shriner’s Hospitals for Children.

Each year Pittman works directly with the Tarzan Zerbini International Circus based out of Las Vegas, Nev. to choose the circus acts, be it dancing bears or white-knuckle aerialists. Although Tarzan Zerbini has its own clowns, they take a rest for this gig as the Red Devil Clowns and other Shrine clown groups from Rome, South Fulton and elsewhere suit up to entertain.

“In my opinion they’re probably some of the most dedicated Shriners out there,” Pittman says. “Their passion is the children.”

Having just exited a school bus, kids begin squealing as they see Vlass emerging from his RV. A gaggle of fellow clowns are hanging just outside the door donning their own regalia.

The Shrine Clowns refer to each other by their stage monikers, admitting they don’t know the real names of many of the fellow volunteers. This particular pack begins warming up for the show by poking fun at each other and telling stories of antics you won’t see in the circus arena.

Naturally, practical jokes often occur in clown alley. Gary “Shoofly” Lewis of Buford recalls once entering his trailer only to find himself knee deep in packing peanuts, which filled the entire vehicle.

Ric “Ka Boom” Miller, a white-face clown, jumps in and exclaims, “I got my tongue pierced!” From his pocket he reveals a latex tongue that’s skewered by a hoop earring.

The props, the costumes and make-up add up, and each clown is responsible for his own. Vlass says he’d rather not estimate what he’s invested into clowning, while Lewis says he’s spent more than $1,300 on one custom made outfit and a pair of clown shoes alone.

Show time closes in and the clowns join their brethren walking toward the arena. Once there they’re each hit by a barrage of kids clamoring for autographs, a Shrine Circus pastime. Like most Shrine clowns, Tom “Buckshot” Houchins of Decatur keeps a marker on hand to sign event programs, T-shirts and hats.

The circus cranks up and the clowns put their Sharpies away. A few acts into the show, and it’s their turn to step into the spotlight with their own original skit. The gang hits the floor with a portable toilet on wheels, a prop the clowns built themselves.

For this particular sketch, Vlass, nose and all, is the star. After proclaiming “I gotta go,” he lumbers into the potty and shuts the door. Time ticks away, and the other clowns become impatient. A joker named Snooze then tosses a bundle of faux dynamite inside the rolling latrine.

With a loud pop the walls of the latrine fall down revealing Vlass’ clown persona wearing a life preserver and fishing in the commode. Waves of laughter flow from the kids. Another job well done.

The laughter proves to be the ultimate award for Vlass, one he cherishes more than the money or time he donates as a Shrine clown. And that sound is even sweeter in a hospital, he says.

“When you’re performing for kids at hospitals you see that even after all that they’ve been through, they still have a positive attitude,” Vlass says. “It’s a beautiful thing.”

Through Sunday. Midway carnival hours: 5 p.m.-midnight through Friday; 10 a.m.-midnight Saturday; noon-midnight Sunday. Circus times:11 a.m. and 7 p.m. today; 7 p.m. Thursday; 11 a.m. and 7 p.m. Friday; 11 a.m., 1, 4:30 and 7:30 p.m. Saturday; 1, 4:30 and 7:30 p.m. Sunday. $10; $6 ages 6-11; free for children 36” tall and smaller. Admission includes access to midway carnival and circus. Jim R. Miller Park, 2245 Callaway Road, Marietta. 770-425-2331, www.circus2012.org.