Of his debut as an artists’ model, Yoni said, “The first time, I thought I was having a heart attack, but it was actually an anxiety attack.”

In a few minutes, Yoni Baker is going to take off all his clothes.

I will see him naked. I know it. He knows it. The camaraderie we established in the past hour over coffee has been replaced by an awkward silence as we walk across the parking lot of the Art Institute in Mission Valley. At the school’s entrance, he holds the door open for me, presents me to security, and leads me up the stairs to the classroom where, momentarily, I will see his bare bottom and his penis. We have known each other for two hours.

Fifteen or so students, all of whom look between 17 and 23 years old, straddle wooden art-horse benches, sketchpads open and propped on a vertical board in front of them. There are holes in the knees of their jeans. Some sit quietly, doodling or playing with smartphones. Some chat with their neighbors. A few are just getting settled. Almost all look up when we enter. Dzu Nguyen, the drawing and anatomy instructor, a young guy with a ponytail, jeans, and Vans, also looks up from the podium at the back. He greets Baker by his first name.

The scent of something beefy and garlicky follows us into the room, a reminder that the culinary programs share this building with art, fashion, and design. I sit at a table off to one side while Baker disappears into a back room with his duffle bag.

Etiquette, he has explained, requires that he undress out of sight.

A few minutes later, while Nguyen takes roll call, Baker emerges from the back room wearing a dark-blue robe that reaches down past his knees. He sits on a chair against the far wall and does not look in my direction.

The blinds on the windows have been drawn. At the front of the room, a spotlight stands lit beside a narrow stage. After roll call, Nguyen turns off one set of fluorescent overhead lights, emphasizing the pool of light.

“Okay, we’re doing arms tonight, FYI,” he says to the students, who have stopped talking. Pencils in hand, they appear ready and eager to draw. “This will complete our tour around the upper body. Are there any questions on the chest, torso, back, or shoulders?”

No one responds.

“Okay, Yoni,” Nguyen says from his station at the podium. He turns on an XM roots-reggae radio station that feeds into the room’s sound system. “Why don’t you give us some warm-ups.”

As Baker approaches the spotlight, he unties the robe’s belt. The quiet in the room is replaced with the sound of Bob Marley’s “Buffalo Soldier.” Baker takes off his robe, lays it across his duffle bag on the floor, and steps up onto the stage. Naked.

An hour and a half ago, the 37-year-old sat across a small table from me, sharing the specifics of his life as a special-effects make-up artist and artists’ model. In the days leading up to our meeting, I’d figured him for a gregarious, almost-overbearing type, based on the number of exclamation points in his text messages.

“Have a nice day!!!!!!,” he’d sent more than once.

His Facebook page, too, suggested a wild side that was absent at our coffee date. His cover photo shows him yielding a sword in each hand, the muscles of his shirtless torso and arms defined, and his mouth set in what looks like testosterone rage.

That image doesn’t match the quiet, respectful guy with neatly trimmed facial hair, sitting across the table in a Fenton Marketplace coffee shop. At first, as he told his story, he spoke in a bit of a monotone, his eyes averted, his face void of much expression — save for moments when he offered particularly revealing details.

Of his debut as an artists’ model, he said, “The first time, I thought I was having a heart attack, but it was actually an anxiety attack.” His gaze met mine briefly, as if he expected to see surprise on my face.

Then he looked away and continued the story. He would do this repeatedly, giving an impression of shyness and reserve, although occasionally, when he looked directly at me, I’d glimpse something mischievous in his eyes.

For nearly 15 years, Baker has been a special-effects make-up artist, one of three regulars who work the Gaslamp’s Haunted Hotel every Halloween. Although the job provides a month of consistent work (and pay), the rest of the year is less stable, at least as far as make-up work goes. Recently, Baker did the make-up for a series of webisodes called Tales of a 5th Grade Zombie Slayer. He also worked as actor, make-up assistant, and stunt guy for Neshima, an independent feature about, as its Facebook page declares: “a reluctant warrior [who] must fulfill an ancient prophecy and bring her people to their sacred home, Neshima.”

“It was a fur-and-loincloth type thing,” Baker said. “We were called the Goran. I was just sort of Barbarian Goran Number Four, not really a specific character. Hopefully the [sword-fighting] stunts I did will be in the final version.”

Because the make-up jobs are inconsistent, he’s held a number of positions to keep him fed between gigs: assistant manager at Sharper Image, team leader at a pet store in Del Cerro, digital retoucher at a photography studio in La Mesa. But closures, restructuring, or inflexible bosses brought all these to an end.

A couple of years ago, at a make-up trade show in Pasadena, a longtime friend suggested that Baker try modeling for artists.

“It took a couple of years for me to give it a shot,” he said. When I asked what kept him from jumping on it right away, he said, “I guess the nudity and getting over that. It’s like when you’re a kid and you have dreams about walking into the school in your underwear, and you’re embarrassed.”

In May 2012, when Baker finally decided to give it a try, he emailed several local art schools, sent them body-building pictures of himself, and asked for advice on getting started as a figure-drawing model. An instructor named Jesse Fortune at World Gallery in Costa Mesa responded by offering Baker an opportunity to model for an art class in two or three weeks. Fortune suggested that Baker go online and look at poses in classic paintings and sculptures.

“I worked out really hard,” Baker said, laughing. “I’m, like, if my muscles are good, then everything else is good.”

He has experience as a sculptor and some idea of what poses would be interesting to artists. Both of his parents are artists (his South African father is an architect, his Israeli mother a painter and sculptor), so he’d been exposed to art all his life.

“It’s funny,” he said, “there’s this big drawing of my mom, it’s nude, and it was in my living room growing up. My friends would come over and go, ‘Dude, your mom is naked on the wall.’ And I’d be, like, ‘Well, I guess, but I don’t really see it as my mom.’ They never really grasped that. It was weird for them. [But ] it was just always there, part of the house. I love it. It’s a great piece.”

A beat later he says, “I don’t know if I’d have it in my place now, though. At my folks’ house, it’s okay.”

Baker laughs, then continues his story.

“So, the day of the class, I’m getting ready, shaving and whatever, and I feel this pain in my chest. It sort of radiates to my left arm, and I’m, like, This is a classic symptom of a heart attack — who am I going to call to say goodbye to? So, I call my girl and she’s, like, ‘I think you should relax, you’re probably having an anxiety attack.’”

The pain soon subsided, and Baker got in his car to make the hour-and-a-half drive from Santee to Costa Mesa. When I asked what kind of self-talk he employed in the car on the way, the corners of his mouth turned down and he shrugged dismissively. “I just jammed to the music in my car and chilled out.”

That day, he stepped out of the changing room in an old, itchy, blue-plaid robe of his father’s. It was too small and hit him above the knees. When it was time to take it off, he did.

“[Poses] just came to me,” he said. “I draw from movies I’ve watched, action heroes, comic-book heroes, all the sculpture I’ve done and seen, paintings. You know, I’ve [taken] all this in, and I’m using it for my motions.”

The instructor helped put him at ease.

“He was a calm guy. ‘Stop stressing out, you’re doing great,’ he said. I just went with the flow, and it turned out to be a really good thing. And that’s kind of how it’s gone.”

These days, Baker models for 10 to 15 local and regional art programs, and sometimes privately for individuals or small art groups, for a total of 15 to 20 hours per week, at $20 an hour. He has secured some work through booking agent Brook Castrejon Solis, who receives a fee from the schools and programs.

“I also get a lot through my own tenacity and networking with artists,” Baker said. “Artists will give me names and references. They’ll post pictures they’ve done of me — either in the class or on their own time — to their Facebook pages, and include a link to my page. Some people find me that way.”

Models work in 20-minute increments, and a single pose can last anywhere from 30 seconds to nine hours. In the case of 30-second poses, the model will set a timer and change position every 30 seconds for 20 minutes. For a nine-hour pose, he or she will hold the same pose for 20 minutes at a time, with five- or six-minute breaks in between, through as many as three three-hour sessions (usually held on a single day of the week for three consecutive weeks).

“You have to think about what your body can do for two minutes or three minutes,” Baker said. “I found that out the hard way. I did some dynamic poses for too long.”

He stood up from the table, then squatted with one leg stretched out to the side to demonstrate.

“If you’re doing something like this, then all the pressure’s on one leg,” he said. “For a short sketch, it’s awesome for an animator, because it’s, like, ‘Oh, cool, it’s Spiderman,’ but for longer than a few minutes, it’s going to suck.”

Returning to the table and his iced coffee, he said, “I sorta had to find out which muscles to engage to take the pain away or to support me in another way. So, it was a whole learning process.”

This evening, at the Art Institute, Baker begins with a series of two-minute poses, setting a timer placed on the floor near his feet. For most positions he is standing, limbs held in asymmetrical positions. The first few poses are done prop-free, but Baker later uses swords, a pole, and a toy gun pulled from his duffle bag to create naked-man-and-weapon poses. The definition of the muscles in his legs, abs, and arms creates small valleys of shadows all over his body. But for these short sketches, the instructor urges students to capture only the shapes of the model’s gestures.

The beeper sounds every two minutes. Bob Marley sings “Natural Mystic” and “Three Little Birds” before another reggae artist gets his turn on the station. Nguyen writes on the whiteboard: humerus, radius, ulna, brachius, bicep, tricep, flexors, extensors, and so on. Meanwhile, the students draw quietly, adding the soft scratch of their charcoal pencils or the occasional turning of a sketchpad page to the room’s sounds.

Earlier, Baker explained: “Learning not to be self-conscious was a process. What helped me was going around and looking at the art [that the students created]. It helped me see this is not about being Yoni, it’s about what my body’s projecting and the story I’m telling. But I still get nervous. It’s like going onstage and performing, in a way.”

To calm his nerves, once he’s in a pose, he either thinks about nothing or about anything but the fact that he’s the one naked person in a room full of people who are fully dressed.

“I’ll think about a gym routine or what my schedule is or what I’m going to eat, because I’m always hungry.”

Baker spends approximately two hours a day working out, sometimes at the gym, sometimes running up and down the convention-center stairs with his girlfriend, Kim, a probation officer with two daughters.

“She’s Jewish and she works out,” he said of Kim. “My mom can be happy now. But she still isn’t.” He laughs.

When I asked what a guy with a million clearly defined muscles and no body fat would be self-conscious about (besides, of course, his penis hanging out for all to see), he said, “Well, one of the questions I got when I would tell people [what I do] was ‘Did you ever, you know, get an erection onstage?’ I haven’t, but I’ve heard of people who have dozed off and it happens. In the beginning, it was fear, like, Oh, my God, it’s happening. Don’t look down. So, yeah, that was one of my main fears.”

These days, he said, that fear has subsided, making way for a more general anxiety about doing a good job. “I’m just really hoping I’m giving them a good pose.”

When the first round of 20 minutes of drawing is up, students copy Nguyen’s notes from the board while Baker sits quietly in his robe. Then, for a half hour or so, the instructor uses his laptop, a projection screen, and anatomy software to discuss the muscles and bones of the arms, how they connect to one another, their jobs, and so on. The lesson is in such excruciating detail that one girl falls asleep, two at the back of the room play with their smartphones in the dark, and others stare at the screen, glassy-eyed.

It gets interesting again when Nguyen calls for Baker and requests four five-minute poses, during which Nguyen demonstrates drawing in layers, using Photoshop.

Baker again disrobes, sets his timer, and starts his poses.

“Find that gesture, and then attach the muscles to it,” Nguyen says. The cursor creates the quick shape of Baker’s back and arm. He switches color from dark gray to red, which he then uses to draw the musculature. “Whenever you’re faced with a difficult pose, look for the origins and insertions. I’m looking for the spine of the scapula.”

He uses a brush setting and a different gray to get shadow shapes; over five minutes, the parts of Baker’s body take shape on the projection screen.

The sleeping girl still sleeps.

While he poses, Baker’s face remains expressionless

Two days later, after claiming to have found his niche in the anatomy classes, he sends an excited text describing an elaborate costume, complete with props, that he used to create “kind of a one-man play” for the students at the San Diego Art Institute in Balboa Park.

“I felt like a little kid up there, acting out one of my childhood and adult superheroes. There was one pose, right before I revealed I was Superman, where I leaned forward and pulled my coat off of a chair, papers all around me, notepad on the ground. I had that look of imminent danger. One of the artists had this big smile, and he’s, like, ‘Superman!!’ I can’t describe the feeling I got. :) Just amazing.”

I text back, “Did you get naked?”

“I had on a Speedo under. Superman doesn’t pose naked. :)”