For those of us still pleased to remember the painted exquisites who made up Japan, the posters promoting Mick Karn’s recent Bestial Cluster album were reassuring. Japan, of those whose memories may prove recalcitrant, were the band who spent the late 70s and early 80s injecting art rock with understated glamour. Some thought that Princess Diana modelled her coiffure on David Sylvian’s (Japan’s lead singer), and even if she didn’t, the thought that she might have was a measure of their chicness. Elsewhere musicians and romantics alike were intoxicated by the melancholic weave that the band’s instrumentalists – bassist Karn, keyboardist Richard Barbieri and, on drums, Sylvian’s brother, Steve Jansen – achieved.

And then, for a few months at the end of last year, Karn’s dark, woad-loaded face stared out with baleful expression from every available hoarding in London – and probably the city centres of Paris, New York and Tokyo, too – throughout the short tour that accompanied the release. He looked like an extra from Apocalypse Now or, perhaps, a minor demon. Certainly his approach to face-painting had changed, but the mask of full make-up which both protects and separates was very much present.

Today, on stage and off, Karn cuts a quiet, elegant figure. The acrimonious atmosphere surrounding Rain Tree Crow, Japan’s last album in all but name, has dissipated. Sylvian remains incommunicado, but Karn, Barbieri and Jansen continue to share a close and relaxed relationship: in fact, they have recently formed their own label, Medium. It seems that the flurry of Karn’s working life has finally settled. With guitarists David Thorn and Terry Bozzio (Frank Zappa’s long-time percussionist), he also has a new band and a new album – Polytown – and a long-term contract with the German label CMP.

For Karn’s part, Polytown’s antecedents are impressive. Since 1977, when Japan’s first album Adolescent Sex, was released, he has built up a formidable reputation as a bassist and multi-instrumentalist. By the end of that band's career, documented on albums like Tin Drum (1981) and Rain Tree Crow (1991), Karn’s self-taught technique had a recognisable character which he continued to elaborate over a series of solo releases and collaborations. His bass playing confirms to few roles. It is fluid and rubbery; Karn typically uses every inch of his guitar neck to produce sounds. His notes can leap into air and blackness, before landing to pick up the node point of another rhythm. He does not speak about the physicality of his relationship with the bass’s heavy-gauge strings, but the calloused fingertips bear mute testimony. During periods away from the studio, he sculpts elongated arms and hands in bronze; 13 years ago he used to serve up home-made biscuits, meticulous reproductions of human fingers, knuckles and all, to friends and passing journalists.

If these off-duty pursuits emphasise a preoccupation with dexterity, his latest recording has been used as a way of creating some kind of framework capable of containing a major talent. Karn remembers a crisis of confidence precipitated by reactions of his first solo album Titles, in 1982. “People were starting to talk about my bass playing: saying that I was the best in the world, blah blah. I didn’t want that. I wanted to be seen as a composer, instead of just a bass player. It was probably a big mistake on my part, but that’s where the subsequent album, Dreams Of Reason Produce Monsters (1986), comes from. It is very much a compositional album; I wanted the bass to take a back seat.”

Together with Torn and Bozzio, Karn agreed the Polytown project around certain guidelines. “It took us three weeks to write, mix and produce,” he says. “This was the time we set ourselves; we laid down a rule that we would turn up at the studio on the first day with nothing. It’s got a young, brash character about it, one that hasn’t needed much development. In fact, we didn’t want to develop it too much. We wanted to experiment and see what happens.”

The results are unfailingly interesting, very different in character from Bestial Cluster or Jansen, Barbieri and Karn’s first Medium release Beginning To Melt (both reviewed in The Wire 120). Karn locates the essential difference between Polytown and its forebears in an issue of freedom, and hearing the album's extremes, it is possible to understand what he means. Polytown’s sound is somehow looser, while Torn fripps away (“He doesn’t like that tag too much,” Karn murmurs), Bozzio and Karn are left to their own devices. They seem capable of anticipating one another's moves to an extraordinary degree, the effect is like hearing an abstracted shape flexing and tensing.

Games of displacement like this are perhaps more readily associated with jazz and improvisatory music. Although CMP has a jazzy reputation (as do Torn and Bozzio), and Karn has been compared to the late Jaco Pastorius, his relationship to the idiom is problematic. He readily reveals a certain distance from jazz and is irritated by critics who suggest that he is striving to appropriate a jazz audience. “I’m a wild card for Bozzio and Torn. That’s the attraction. I’m someone who neither knows the rules of jazz nor how to break them.”

David Torn figures large in Karn’s life. The former everyman guitarist was introduced to Karn’s music when Jan Garbarek gave him a copy of Titles, saying (according to Karn), “Listen to this bass player; I don’t think he knows what he is doing.” It was a prescient remark. By this time, after two years, two sackings and two re-signings by Virgin, Karn has stopped playing completely. Although both Titles and Dreams had sold tolerably well, Virgin were not sure where Karn’s audience was and the struggle to continue work was an uphill event.

“I continued sculpting, I learnt History of Art,” he says now. “It was only through the persistence of David that I got back into music. I now look on him as almost being the person who saved my life musically. He was so insistent that I play on his 1988 album Cloud About Mercury (ECM), which I did everything to avoid doing; in the end Tony Levin played bass. I did the same when David called up about the tour; finally, I felt that the only way I was going to get this guy off my back was by showing him that I was suited for the jazz world. So I went to Germany, had three days of rehearsal with Torn, Mark Isham and Bill Bruford. I was used to three weeks of rehearsals, Suddenly, I was about to go onstage. I had to learn to love my instrument all over again.

“I hadn’t played bass for a couple of years, I hadn’t even picked one up. I was completely nervous, completely out of my depth, a nervous wreck, basically. After two days, I said to Isham, ‘I envy you, you have this incredible repertoire, you can play anything whereas I am struggling around to hear the notes I should be playing because I can’t read music.’ He said, ‘It’s taken me 20 years to forget everything I ever learnt to find my own voice. You started with your own voice and now you are doing the training – and that’s a much better place to start.’”

Such a crisis of confidence might give some indication of Karn’s fragile psychological processes, but for anyone familiar with his work, it is unfathomable. A muscular confidence runs through his work and, on album credits, a list of instruments, including sax and woodwind, always follows his name. “Something of a myth has grown up,” he says. “The biogs always say that I am a multi-instrumentalist and that I had a background in classical music. Yes, I was in the LSSO (London Schools Symphony Orchestra) as a bassoonist, but I was never really classically trained. They tried to train me, but it really never worked.

“As an adolescent, I’d always wanted to play an instrument. I observed that other people seemed to enjoy it, and I wanted to find the one that would make me feel the same. I tried the mouth organ, the violin. I was lucky in my choices. I was slow at reading music and I relied on playing music by ear. The same thing happened with the bassoon. I’d been playing for six month and there was an audition for the LSSO which my school sent me to. I went along; they were thrusting sheets of music in front of us as tests. I asked the guy next to me to play it so I could pick it up quickly by ear. Somehow I got chosen and that devastated me; it was the last thing I was expecting. I was playing in an orchestra when I wasn’t up to the job. Instead of being the enjoyable thing I’d envisage, it was very traumatic.”

Rescue came from an unexpected quarter. “On my way home to Catford (one of London’s less salubrious districts) after the first LSSO concert, my bassoon was stolen by a group of skinheads. They asked me what was in the case. I told them. They showed me a broken bottle. I gave them the case. It was very simple. The school wouldn’t buy me another bassoon, so in retaliation I bought a bass for £5 from a kid at school and got together with David [Sylvian, né Batts] who was playing acoustic guitar.”

It was 1974, and transgression was the order of the day. Lou Reed, Bowie, Iggy Pop and The New York Dolls were powerful presences for youthful Karn (né Michelides). Percy Jones, a cornerstone of Eno’s early albums, exerted a pull on the fledging bassist. 20 years on, Karn’s making startling revelations. “I don’t know where all the notes are on the bass,” he says, “and I don’t want to learn.” It’s an off-kilter way of declaring an adventuring spirit. Think about it.