The first time Dominic Blake took his clothes off in front of an art class was, as you might imagine, a daunting experience. “I was still wearing my gown,” he says, “and I had beads of sweat pouring down my face. There were about 40 people and I was looking at the doors and windows for escape routes.”

If you have an image of what a life model might be like – someone with a toned physique, perhaps, and an exhibitionist streak – then think again. “At the time I had the most negative attitudes about how I looked,” says Blake, 40, seated in the Royal Academy’s life drawing room where he often works. “And those attitudes crippled me. I didn’t have the normal experiences people usually have growing up. I didn’t have a girlfriend until I was in my mid-20s.”

Yet something magical happened after Blake disrobed. The artists started adjusting their easels, measuring him up, and drawing. Blake realised they were treating him no differently to any other person. “Then I saw the paintings emerging and it was the most incredible thing. I realised we were all travelling on this journey together. It was incredible, like sorcery.”

Up until this point, Blake’s work in various museum admin positions had seemed somewhat meaningless. But here, naked and still, he genuinely felt part of the creative process. “I just wanted to create something beautiful,” he says.

Suzon Lagarde, a painter, wasn’t comfortable with the idea of nudity, either, when she decided to step over to the other side and pose naked. “But I didn’t really think about the nudity,” she says, “because I was so obsessed with my hands.” The 25-year-old was born with amniotic band syndrome, which causes missing or malformed fingers and toes. This made her doubt whether she could become a life model – it took Blake to convince her that she could.

“I’d been waiting for someone to tell me it’s fine to pose for students if you’re different,” she says, over coffee near her London studio. Like Blake, Lagarde says her hang-ups quickly dissipated. “That’s the beauty of doing this,” she says. “You might feel vulnerable posing, but as a painter I also know how vulnerable people can feel behind the easel – you are always questioning and judging yourself. I soon realised we are a team, all trying to be brave.”

Blake is currently preparing to be brave once more. He’s about to deliver the first of several talks in art galleries on the contentious subject of Are Life Models Artists? His position is that they are more than simply source material for painters – they’re creative partners who use their bodies to “paint” the space around them. A look at his Instagram reveals where he’s coming from – with some beautifully contorted poses that resemble dance or performance art.

“The role of the life model has long been that of the servant or slave,” he says. “There’s a hierarchical power structure: the artist is up here, the model down there. I want to make them more even and reclaim the creative dimension that the model brings.”

Blake says he’s often asked after sessions if he’s an artist himself. “What they mean is: do I draw, sculpt, paint, take photographs?” He was once asked this straight after inhabiting a pose inspired by a character in a Titian painting: “I thought, ‘Look at what you were just drawing! What did you think that was? That was the work of art right there – and now it’s vanished.”

Blake had no idea his body could be so flexible. As he experimented, he realised he could create unique poses inspired by all sorts of things: branches in a tree, for instance, or poetry and music. “Even this interview!” he says. “I’m being serious. Because doing this interview is making me happy, so my poses later could be really open, whereas when I’m feeling depressed my poses can be more compact.”

Being a life model isn’t easy. It can be painful, it can be boring, and it requires focus. “There’s an amount of pride involved where you don’t want to break a pose, even if your arm has gone dead and your leg is in agony,” says Blake, who says he is currently working 18-hour days, six to seven days a week. “Minutes can seem like hours, it can be nightmarish. But you learn what your body can handle, and how to shift your weight making micro movements that aren’t perceptible.”

Lagarde agrees: “I’ve been life-modelling for a year and I’m already feeling it in my knees and hips. I wasn’t expecting to because I’m young and fit, but you are often putting the weight on the same side.” Does the job ever get her down? “Of course, there are days when I’m not feeling so good and don’t feel I want to be naked. But that is like any job.”

Blake has his share of funny stories, like the time the room was so hot, the model posing alongside him fainted and collapsed on top of him, or the time a woman was so displeased with his position that she walked right up and just moved his legs herself. “That may reveal attitudes that exist within the life room,” he says. “That models are effectively objects. Because you’d get arrested if you went up to someone and did that in any other situation.”

For Lagarde, the negatives have been more cutting. There are the classes where she can tell that painters have been focusing on her breasts, or she’ll hear comments like: “You look so sexy.” Worse, though, was a nine-day project in which a student decided to ignore what he saw and paint her with regular hands. “That was disturbing,” she says, “but he wasn’t a good person anyway.”

For the most part, though, it has been a positive experience, especially in how it’s changed her outlook towards painting. By posing, she gets to absorb the advice from different tutors, observe the techniques of other artists, and focus her mind (“I love being able to stare at one spot for six hours – to imagine what colours I would use to paint it”). Furthermore, seeing how other artists approach painting her fingers – often ignoring the finer details – has forced her to question her own practice: “Because you’re like, ‘I’ve seen a shoulder before, I know how that is.’ But you don’t know this person’s shoulder. So how little do we actually look?”

Not all models come to it through the art world. Craig Donaldson first encountered life drawing when he was on a stag do (yes, really – life drawing has apparently become a thing on the stag and hen circuits). He didn’t get much out of the drawing side, but he thought it might be fun to start posing for others. “The atmosphere was much more relaxed than I expected,” he says.

Donaldson’s reasons for modelling are different to Blake’s and Lagarde’s. “I like the attention,” he says. “It’s nice that there’s 30 people who are going to spend two hours looking at you. That’s quite an ego boost.” Donaldson’s different approach is partly reflected in the places he models, which can be more relaxed: he’s done classes outside, in pubs and on gay stag dos where “people aren’t really drawing, they’re just there to perv at you really. And I don’t really mind that.”

One hen party all wanted to touch him during the modelling and get a photo afterwards. Donaldson was already pretty confident about his body, but life modelling means “now there’s another reason to go to the gym. I wouldn’t want to get fat and not be wanted.”

Can that happen? Not in the art world, says Blake, who claims the idea that people only want beautiful, slim, female nudes is a myth. “The reality is you want to draw different people, different ages, sizes and shapes. It would be boring to draw the same type of body every week.”

So what of Blake’s central question: can life models be artists? Unsurprisingly, Donaldson doesn’t consider himself an artist, although he’s open to the idea that life modelling could be an artform. “If you’re directing things then it could be,” he says. “Generally, you are choosing the poses you’re doing, the artists don’t have control over that.”

Lagarde takes a similar view – she says it would be too exhausting to consider her whole life as an art practice, but believes modelling can be elevated to an artform by people like Blake. “It’s so hard to define art, but it has a lot to do with the presence and sincerity you bring. For me art is about offering another perspective, and he does that.”

Blake’s belief that life models can be artists brings with it a whole political dimension. Because if they are contributing to the finished work, should they not be entitled to better pay? “There are studios where I’m paid less than the cleaners,” he says. “Of course they should be paid enough money to live on, too, but I feel quite irked by that.”

Lately, Blake’s started negotiating a percentage of any work’s eventual sale fee: “I wouldn’t dream of doing that unless I felt I’d truly collaborated,” he says. “And it doesn’t have to be 50/50. But some painters who have asked to work with me are selling works for £40,000. It would be grotesquely unfair if my cut was £200.”

Of course, as Blake acknowledges, there is another argument: that painters train for years to reach the level at which they can produce paintings that command a fee. “But I still feel that if you’re painting a portrait you’re extracting someone’s soul.”

Lagarde says modelling has encouraged her to pay her own models a better fee, around £20–£25 an hour. But she is unsure about whether models should be commanding a percentage of a sale: “It can take me six months to finish a painting in my head, and I don’t feel I owe the model for that six months. But I need to value their time while they’re here. That’s why I don’t like people taking pictures of me. It’s not so much that they’re taking a picture of my nudity, but that they’re taking my time.”

While fair pay is an issue, none of the life models I spoke to are really in it for the money. For each of them, in different ways, it involves a mix of confidence building, physical challenge and emotional satisfaction. “Sometimes it’s powerfully moving,” says Blake. “I’ve been known to burst into tears at the end of a session.”

• Dominic Blake’s Are Life Models Artists? is at Mall Galleries, London, on 15 August. Suzon Lagarde’s work is on display at Mall Galleries until 17 August.