The Chapman Brothers on life as artists' assistants: 'We did our daily penance'

'It was hard labour by any measure," says Jake Chapman, recalling his and brother Dinos's apprenticeship as assistants to Gilbert and George. "There was absolutely no creative input at all. They were very polite and it was interesting to hear them talking – as we did our daily penance."

What did the work involve? "Colouring in their prints. We coloured in Gilbert and George's penises for eight hours a day." At least you didn't have to pay, as Rembrandt's assistants did, for the privilege of working in the master's studio. "Oh, we paid," retorts Chapman. "We paid in dignity."

The relationship between artist and artist's assistant is vexed, ripe for oedipal tensions, mutual resentments, or at least spitting in the great master's lapsang souchong. How tired, one suspects, Lucian Freud's assistant (and painter in his own right) David Dawson, got of being called "Dave the Slave" by his late master.

John Lanchester's recent novel Capital captures this two-way vexation when an artist called Smitty, modelled on Banksy, sacks his assistant. "The decisive factor was his assistant's way of making it clear that in his judgment, he and not Smitty was the person who should be treated as the famous artist," writes Lanchester. "The fact that he hadn't actually made any art since leaving St Martins, the fact that all he did was chores for Smitty, seemed in his mind to be a minor, disregardable detail ... Well, thought Smitty, he can piss right off with that."

But what's most striking about the artist-assistant relationship is how it is airbrushed from public consciousness. Behind every great artist might well be a highly skilled team of assistants, but that truth is suppressed for fear of shattering our illusions: the lone-genius myth helps sales, and is partly what gives an artwork its mystique.

When David Hockney's 23-year-old assistant Dominic Elliott died on Sunday after being rushed to hospital from the artist's home in the Yorkshire town of Bridlington, much press attention focused on the entourage the artist has working for him. Elliott had helped Hockney install his show last year at London's Royal Academy, and worked as his driver. Hockney has several other assistants working for him, including a full-time technical PA with his own staff. He has a film crew who have toured the Yorkshire Wolds to make landscape film productions, using nine video cameras. Suddenly Hockney's unremarkable seaside house seemed to be an art world Tardis concealing a hitherto ignored workshop of assistants, like Andy Warhol's Factory, though – with respect to Bridlington – less glamorous.

Giving up that lone-genius idea is hard. "The idea of the genius struggling in solitude in a cockroached and frozen garret with only a crust of bread and syphilis for company is an historically specific vision no longer, if ever, of relevance," argued Stephen Bayley this week writing about Hockney's studio. "Artists are not solitary. They rely on human support systems, often of a very sophisticated sort."

No doubt, but there's more of a paradox here – and more pathos – than Bayley allows. It's Tracey Emin's name on the tent, even if an unsung underling worked on the stitching. Many minions painted Damien Hirst's dots (among them was Lauren Child, who went on to create Charlie and Lola and, when I tried to talk to her about it, preferred not to remember her grunt work) even if he took the credit for the results. Even if Hockney's RA show was the work of many (not least those who built his iPad), it was his name that induced art lovers to queue in the rain in Burlington House's courtyard.

Earlier this week, a 17th-century portrait of a man in velvet hat and two ostrich feathers was re-attributed to Rembrandt after more than four decades of having been assumed to have been painted by one of his pupils. The painting, which hangs in the dining room of Sir Francis Drake's old home of Buckland Abbey in Devon, clearly depicted the Dutch master and bore Rembrandt's signature, but that was long regarded as no guarantee that he painted it. New x-ray evidence suggests it was his work alone. The re-attribution made the painting newly important, even while it remained physically what it was the day before. As a result, according to David Taylor, curator of paintings and sculpture at the National Trust, the self-portrait now becomes "one of our most important works of art and will be the only Rembrandt in the National Trust's collection of approximately 13,500 paintings".

For Chapman, this is disturbing, since what he calls the "possessive claim" on a work of art obscures what makes it worth seeing. "The 'I' eclipses the thing. When someone slings our work on the back of a van, for me it's gone and no longer mine. What a relief! After it goes, the work is open to interpretation. The artist stands by like a spurned village idiot."

But what about the assistant who sees in the gallery a work to which they made a decisive contribution, and yet is labelled only with the artist's signature? What about all those poor saps who paid Rembrandt and then wound up helping him to crank out paintings for which he got the kudos? Chapman is unsentimental: "Does the person who makes the hubcaps or whatever they're called these days – low-profile sports rims – point at a passing Mercedes  SLK or whatever it's called, saying, 'I did that?' No. So why should assistants claim possession for their work? It's a job."

Mike Smith has produced work for artists, including the Chapmans. In 2001 he and others assembled an 11-and-a-half ton polyurethane resin piece on the fourth plinth at Trafalgar Square for artist Rachel Whiteread. It took three years to make. Not that Smith was complaining. "There are people who latch on to the fact that artists are not making things themselves," he told the Guardian last year. "The moral outrage – the idea that we're all being duped because we're paying all this money for work that's not being made by the artists themselves – is ridiculous."

There can, however, be a great deal of pathos in the role of the assistant. Ashley Hipkin has worked as one of sculptor Antony Gormley's assistants for the past 10 years. After graduating in sculpture from London's Central Saint Martins college in 1996, he spent his 20s working in a restaurant and as a builder while establishing a sculpture practice. "I was floundering a bit, but then I moved to the north-east." There he started teaching and garnered interest from local galleries in his work. But, aged 30, he found himself struggling financially, and applied to work for Gormley. "Antony offered me the job and I spent a month debating whether I should take it. But in the end, I accepted. The decision was based on needing a regular income. I had a family by then."

Do you have regrets? "I sometimes regret that I have let go of my own practice. Maybe I'm doing it because I'm not brave enough to strike out on my own. I've gained a great deal of satisfaction of thinking of the work I have done for Antony, but it's not the same as the pride one feels when you do your own work. I have been having that internal dialogue for a long time."

Hipkin learned early on of the pleasures – and sorrows – of being an artist's assistant when, in 2003, he and others worked on Gormley's show Domain Field at the Baltic in Gateshead. They cast 280 members of the public, aged from two to 85, in plaster to create moulds that were then used to make individual sculptures by a laborious process involving welding steel elements together into each mould. It wasn't just technically demanding. "It was a bit of a love-in," recalls Hipkin. "I loved the work. And then suddenly it's not your work any more, but Antony's."

But not, Hipkin makes clear, because Gormley is a grotesque megalomaniac. "It's the media or the world that takes the work away from you. Antony fully realises there are collaborative elements. He sits in on the studio crits, when there are six or seven people taking part in a real dialogue about the evolution of the idea. There's a joint ownership of what's happening, though Antony still has a grip on everything conceptually."

Unlike the Chapman brothers' work for Gilbert and George, Hipkin's work for Gormley is creatively engaging. "Each assistant is given quite a lot of autonomy to push the work forward. Antony drives the work conceptually, but it's very collaborative. I get as interested in his practice and in the relationship between the body and modernism as he does." He's enjoyed the travel the work has entailed, and revels in the creative input. He's thrived too, as Gormley's practice has, as it's become more internationally lucrative in the past decade. Then he checks himself. "Maybe I've painted it too positively. There is an anxiety about ploughing your creative energy into someone else's work."

Richard Wentworth, professor of sculpture at the Royal College of Art, recalls working as Henry Moore's assistant in 1967. He was there for a short term to learn what he could before setting up his own practice. "I was a callow boy at Henry's, but those procedural days stay with me, the sounds of the radio and news of the day.

"For me then there was deference, and an engaging job of work. We made small things bigger. Not such a bad metaphor. It's fun to learn process and procedure in context, and to do more or less what you are told. There's a time limit, of course, and each has to know what's in it for him." Moore needed assistants such as Wentworth and Anthony Caro because of the growing monumentality of his work.

Wentworth's later practice as a sculptor in the 1970s, one might think, turned away from his master's oeuvre: "I find cigarette packets folded up under table legs more monumental than a Henry Moore," he said once. "Five reasons. Firstly, the scale. Secondly, the fingertip manipulation. Thirdly, modesty of both gesture and material. Fourth, its absurdity and fifth, the fact that it works."

It's almost as though Wentworth the ex-assistant had oedipal issues with his former master. "Any close collaboration involves exchanges of power and patience and skill," says Wentworth diplomatically. "Much more fun if there are episodes of co-learning. Henry was benign and said all sorts of 'wise' things, which I still remember." His inverted commas, not mine.

What happens when an assistant becomes an artist and takes on their own assistant? For example, does the hard labour Gilbert and George inflicted on the Chapmans get visited by the Chapmans on their minions? Quite possibly. "So much of our art is about industrialised slaughter, it makes sense it's made by industrialised labour," says Jake. "Perhaps our poor assistants should rise up against us." He's joking. "We pay them well, and they get fed and they have a nice time. As far as I'm concerned, having an assistant multiplies what you can do. It's dependent on the idea that a) you don't have the time to learn a skill, and b) you can't be bothered to learn it." Perhaps there's even a c) the Chapmans learned from experience with Gilbert and George how mind-numbing the donkey work can be and so devolve it on to underlings.

In fact, the Chapmans provide studio space for their assistants to do their own work if they want. "But that's all. I think it's incredibly patronising to get involved in supervising their artistic development. Those philanthropic, paternal gestures are completely alien to us. We're not here to mentor them. They're here to work for us."

Do you get resentful when your assistants get ideas above their station? "Oh yes," laughs Jake. "If there's a hint of them being successful artists, I will fire them immediately." Again he is, probably, joking.