In The Studio: Kader Attia, sculptor

'I like the uncertainty of what is an artwork. I've done pieces with couscous'

Kader Attia lives and works in Berlin, though he still retains both Algerian and French nationalities. He was born in 1970 in France, and his childhood straddled the two countries. He later lived in Congo for four years, serving the Algerian contract for non-military service.

His modest studio is between Prenzlauer Berg and Friedrichshain, "in a non-smart part of town". Multicoloured plastic bags litter the desk; a shelf contains the books he uses for inspiration. "Before I was renting five square metres in the former jail of the Stasi. I could afford only this. I could not stay there; the atmosphere was very heavy. Full of ghosts."

Attia's work is archaeological and based on archival research. His recent monumental piece, The Repair from Occident to Extra-Occidental Cultures at dOCUMENTA 13, was based on the French-Algerian war. "I don't see myself as an artist but a researcher," he affirms. "I am fascinated by the research. I love to see how the notion of history is filled with misunderstanding, and my research takes shapes that some people call artwork."

Attia's work at Tate for the Liverpool Biennial uses couscous, the mainstay of the north African diet. He loves it as a material, he says, as it is "unstable like sand. You see it first as a sandy city and you come back in one month or two months. You get some mould and degradation and all the buildings are collapsing."

Unstable materials attract him, he says. "I like the uncertainty of what is an artwork. I've done pieces with empty plastic bags, aluminum foil, couscous... I love plastic bags." He lifts up a red bag and twists it out of all recognition, transforming it from inert rubbish into a sculptural element that seems to have life in it. He laughs. "I like the way it gradually loses its substance. The artist is the shadow of the art work."

Treasure from Africa played a part in his recent dOCCUMENTA work. He opens some bags, fresh from Kassel, on his disordered desk. "This is the kind of woman that I like," he laughs, kissing a mask of an African woman from Congo.

"My strongest memory when I was growing up was my father who said, 'You know, when you leave a country as an immigrant, the most important is not the country that you leave. It is neither the country you leave nor the one you find. The strongest is the voyage.' It took me 20 years to learn the truth of this statement."

Thresholds, Tate Liverpool ( to 7 April