Martin Hamann, executive chef at the Union League of Philadelphia, has spent as many hours in front of fire as Satan, laboring in hot kitchens from here to Singapore.

He'll display the scars on his hands and tell you the precise dish he was making when the knife slipped. He'll reference his new hip and describe the constant bending over ovens, the hoisting of 50-pound bags of potatoes — the endless culinary calisthenics and 14-hour days of standing in grease and bedlam.

"This is hardcore physical labor," said Hamann, 60. "A chef is absolutely a working-class job."

Not so fast, say experts like Willa Zhen, food anthropologist at the Culinary Institute of America, north of New York City: She said chefs possess artistry, financial acumen, and the white-collar polish for clinking glasses with money-dropping regulars. Plus, they often log years of arduous study in cooking school.

"We are seeing the professionalization of cooking," she said.

So, is a chef white-collar or blue?

Those who study social class say chef is a rare kind of hybrid job — like nurse, FBI agent, surveyor, or geoscientist — that combines college education with hard, hands-on work.

"It's a blending of both classes," said David Jansen, chef-owner of Jansen in Mount Airy. He and Hamann were chefs at the now-shuttered Four Seasons Hotel.

"I'll fix the stopped toilet and peel the carrots," Jansen, 50, said. "But I'll also design the menu, create a plate with beautiful flavors and textures, manage food costs, then be a part-time priest when someone in my kitchen is fighting with his girlfriend."

The toilsome aspects of chefdom are often a surprise to neophytes breaking into the business. Young people who've feasted on a ceaseless diet of television food shows, which elevate chefs to lavishly remunerated rock-star status, walk into kitchens expecting to run their own spots in a year — and instead spend their days chopping onions.

"For people who are smart and physical, there are easier, more lucrative alternatives than restaurants," said Jonathan Deutsch, a professor of culinary arts at Drexel University. A chef's average annual salary is $47,390, according to the U.S. Bureau of Labor Statistics.

Low pay and blue-collar conditions could be why the restaurant industry now has a chef shortage. In Philadelphia and its suburbs in 2016, there were 2,020 chefs in restaurants, 500 fewer than there were 10 years before, according to the Bureau of Labor Statistics. Food cognoscenti around the country report similar trends.

This comes at a time when the restaurant industry is exploding, noted John Longstreet, president and CEO of the Pennsylvania Restaurant and Lodging Association in Harrisburg. For the first time in U.S. history, he said, Americans today are spending more money for food in restaurants than in grocery stores. Nationwide, annual restaurant sales are $798 billion, compared to $587 billion seven years ago, association figures show.

Longstreet attributes most of the chef shortage to all that industry growth — too many kitchens, not enough bosses.

But, he acknowledged, "there's frustration for young chefs looking for the glamour of being Guy Fieri and quitting after seeing that isn't what it's like."

Describing the chef shortage in Philadelphia, Deutsch said it's caused in part by a combination of "some kids not wanting to pay their dues" and chef's wages failing to increase sufficiently to entice new blood, even though "there's a plethora of great restaurants here."

Martin Hamann — his mother a telephone operator, his father a baker — was always drawn to kitchens.  He tried cakes but lacked the temperament for baking, which requires a chemist's exactitude that was foreign to the athletic, blue-collar boy from Morton, Delaware County.

"Maybe you should work in the savory end," Hamann's dad suggested.

He studied at the Restaurant School, now known as the Restaurant School at Walnut Hill College, did some work abroad, then went on to a 25-year career at the Four Seasons, rising to executive chef.

Married with a college-age daughter, Hamann said he never forgot he was a working-class guy "cooking for the elite" at the Four Seasons. One Christmas, he was running out of food as people kept ordering steaks. "I'm in the kitchen wondering, 'Why aren't they at home with their families today?'

"That's a separation of class. The upper class eats steak at the Four Seasons at Christmas. We stayed home."

Creative class

Perhaps it's inaccurate to fit chefs for blue or white collars, mused Megan Elias, director of the gastronomy program at Boston University.

"They're the creative class" making art, she said, adding, however, that line cooks do most of the cooking — earning half of what chefs make: They're "unappreciated, and frequently undocumented immigrants."

Nick Elmi, winner of Bravo TV's 2014 Top Chef contest and owner of Laurel in East Passyunk, doesn't agree that he and his peers are Picassos with spatulas.

"I'm more like a mason than an artist," said Elmi, 37, who grew up in a middle-class Massachusetts family. "Beauty's important, but there's a physical workmanship to it."

Regarding class in restaurants, Valerie Erwin, chef-owner of the now-closed Geechee Girl Rice Cafe in Mt. Airy, said she hadn't considered where chefs stand. She does, however, see a divide preventing working-class minorities from becoming waiters.

"Dining rooms are more segregated than kitchens," said Erwin, 65, a Princeton graduate born into a working-class North Philadelphia family. She currently manages the nonprofit EAT Cafe, a West Philadelphia spot with a pay-what-you-can component that's run by Drexel's Center for Hunger-Free Communities and other organizations. "In a majority-black city, you don't see black servers in fine dining."

Also, it's widely known that "very, very few women are at the chef level at any kind of restaurant," Elias said.

And recent sexual misconduct allegations lodged against famous male chefs — John Besh of New Orleans and TV personality Mario Batali — underscore the degrading macho culture that persists in restaurant kitchens.

But, said Deutsch of Drexel, restaurants are becoming more serious about improving conditions. And they will be hiring chefs who are blended-collar types representing "the full package: physically strong with deft hands, smart multitaskers who can create a delicious roast chicken and 10 other things at the same time."