At a Rockville, Md., salon last week, as a beautician carefully combed bleach through his beard and eyebrows, John Parks sat with the patience of a saint. Saint Nicholas, to be exact. Parks was halfway through his annual transition from black-haired information-technology specialist to white-whiskered Santa Claus.

“It’s a little bit shocking every November,” said his wife, Nelly, 45, watching as her 40-year-old husband morphed into a centuries-old Christmas icon. “This isn’t what I bargained for when I married younger.”

But she knows the kiddies want their Santas with snowy beards. And she appreciates the extra $4,000 to $6,000 that Parks will pocket in appearances over the next several weekends. Mostly, she understands how much he enjoys getting his Kringle on.

“He loves it,” she said, as the beautician crimped foil over her husband’s tresses. “It’s like he becomes Santa for a few weeks.”

Parks is one of a growing number of office workers, teachers and retirees — mostly on the stout side, usually bearded — who work up a little Santa sideline each year at this time. They have discovered that a certain body type mixed with an air of benevolent wisdom — profundity plus rotundity — can mean a month of lucrative holiday gigs, most of them starting this weekend.

Freelance Santas form the irregular Yuletide army that deploys to the countless company parties, home gatherings, school and nursing homes events that fill December. Not for them the workaday, full-time grind of the mall Santa. These are Santas on the move.

“I’ve already got more than 90 events lined up,” said Dale Parris, 65, a retired Marine master gunnery sergeant from Stafford, Va., who has just started his yearly holiday hopscotch around Virginia, including Northern Virginia, Richmond and the Tidewater region. He travels with Mrs. Claus (his wife, Trish), and at $135 to $175 an hour, they often clear $12,000 a season.

“I don’t sit in a chair at the mall,” said Parris, who weighs in at a jolly 270 pounds and estimates he has invested more than $3,500 in his costumes. “A typical mall Santa is employed by a photo company, and they’re not making money on photos if you talk to a child for more than a few seconds. I like to spend time with each kid.”

Parris, who is a member of multiple Santa guilds, said the number of local freelance Santas has boomed in recent years thanks to social media and the ease of advertising on entertainment-booking sites like GigSalad and SantaForHire. He now has more than 100 freelance Santas on his local e-mail list.

He’s even been known to recruit them, accosting pear-shaped, bearded men at Walmarts and gas stations. “You ever thought of being Santa?” he’ll ask. “Sometimes, it’s ‘Hell no, I don’t even like kids. Why do people keep asking me that?’ “

Of course, there’s more to being Santa than sporting a belly and sprouting a beard. Parks started getting into character a month before his date with peroxide. He’s been listening to Christmas music for weeks on his morning commute from Silver Spring, Md., to Lockheed Martin in Arlington, Va. He got a flu shot, had his velvet suit cleaned and stocked up on children’s books to fill his satchel. He’s read “‘Twas the Night Before Christmas” over and over, fixing it in his memory.

“I like to do a lot of research, find new stories to tell the children,” he said in the den of his Silver Spring home, where he keeps his Saint Nick equipment stored in a massive wooden wardrobe.

Parks is a legacy Santa. His father performed the role for a passel of grandkids each Christmas Eve for years. When he stepped down, Parks’ mother asked her son to don the flimsy red suit and the cotton clip-on beard. It was when the children starting getting older and savvier that he knew it was time to invest in some proper Santa wear.

“About five years ago, I decided to step it up a bit,” he said. “I needed a better suit so they couldn’t recognize me so easily.”

He ordered a $700 custom Santa rig. (In Santa World, there are two main suit styles to chose from: the “traditional,” with white fur down the front, and the “Coca-Cola” — made popular by Coke’s mid-century Santa ad campaign — with buttons instead of fur. Parks opted for traditional.)

To help pay for it, Parks posted a Santa-for-hire ad on Craigslist and appeared at his first private neighborhood party. He walked in, the kids went wild and his stage fright melted away. A December routine was born.

He made enough to cover the suit and pay the rest of his Christmas bills, too. Over the years, he’s upgraded to $400 black boots and committed to a real beard, even though it won’t be naturally white for a decade or two. He’ll dye it black again in January.

“Everybody wants the real beard now,” said Carol Turman, a local booking agent who keeps a roster of about 40 Santas for tree lightings, store events and high-end corporate parties. “The ones who get into it like that they can stay real busy.”