Calling Kimmo Pohjonen an accordionist is a bit like describing the Encyclopaedia Britannica as a book - it doesn't begin to convey the vast wealth of detail you'll find therein.

Pohjonen himself describes his five-row button accordion as an orchestra and his role in playing it as creating a kind of aural cinema where listeners can go off on a trip through jungles, dance halls, sea scenes, or wherever their imagination takes them.

Even describing the Finn's performances as ''solo'' is a misnomer, as sound and light engineers play almost as big a part in the production as the man himself.

Sound and light engineers were about as distant a concept to Pohjonen when he began playing as a boy as the deeply impressionistic music he now makes is to the folk dances he used to ''humppa'' out with his village accordion band.

''My father played the piano accordion and he thought I should play accordion, too,'' he says. ''He bought me a button accordion because he thought it would be easier to play than a piano accordion, and because I did what I was told - I was a well-behaved guy - I learned from him. In Finland the accordion is very popular, the unofficial national instrument, really. We lived in a small village but even there we had a lot of players; in our accordion club there were about 30 or 40 older guys - and me.''

As a teenager Pohjonen felt that, somewhere, there was a different, freer musical plain he could move to (the one-time ''well-behaved guy'' is regarded as a bit of a hooligan now by more conventional players back home). But he put that out of his mind and was determined on becoming a classical musician when he became sidetracked by the group Niekka, whose accordionist Maria Kalaniemi has already wowed audiences here through her appearances at Celtic Connections.

Niekka's adventurous approach to traditional tunes convinced Pohjonen that with his early ideas, though vague, he had been on to something after all. Gigging around Finland's burgeoning roots music scene, and with pop and rock bands, helped him develop his very physical style and showed him that the accordion had undreamt-of sound possibilities.

''Carrying 15 kilos around the stage makes playing the accordion a physical experience anyway - as physical as playing the drums,'' he says. ''But what I really love about the instrument is that you can tap the bellows in a certain way and it will sound like something else entirely. You can create sounds like waves breaking or wind howling by making the smallest move. I use amplification to make them louder, to enhance them, of course, but the natural sound of the accordion, its soul, is still very important to me.''

The solo style which he features in concert and on his remarkable CD Kielo has developed over the past five years and continues to develop with every performance. Although the essential repertoire remains constant, no two concerts are ever the same, his compositions, sometimes conceived melodically, sometimes only as moods, being purely a starting point for a voyage of discovery.

''I've written for full symphony orchestras and I like that, too,'' he says. ''But there comes a time with that when you have to sit at the table and write down all the parts. When I'm composing just for me, I don't write the notes down, I just start playing and see where it takes me. It's more like dreaming. When you're asleep your mind goes places you would never go if you were walking down the street or whatever - and it's the same with a performance. Sometimes, I really surprise myself with what I've played.''

In time, he may invite other musicians to join him. But right now he's pretty much self-sufficient. ''I like the freedom of playing solo,'' he says. ''And every day I hear new sounds, new possibilities on the accordion. When I stop hearing new sounds I can expand, but this instrument has so much to offer that that might take years.''

n Kimmo Pohjonen plays the Bongo Club, Edinburgh, next Wednesday and The Arches, Glasgow, next Thursday.

Rob Adams