Anish Kapoor met with Heidi Reitmaier to talk about the third in the Unilever series of commissions for the Turbine Hall at the Tate Modern. As they walked through his studio, they talked about this new work and other sculptural discoveries. Here are some extracts from that conversation in expectation of the forthcoming installation.

The Turbine Hall is an enormously difficult space, mostly because it's unclear about whether it's an art space or not. It is more difficult to look at art there than in the Duveen Gallery at Tate Britain, or in any other space in London. The Turbine Hall is somewhere in between a gallery and a station. The great problem with the space is that it demands verticality. This, is contrary to every notion about sculpture that I've ever engendered in my work. So I felt that the only way to deal with the vertical is in fact to deal with the full horizontal, to take on it's glorious hundred and sixty metres.

What I have done for the space is to make a work, which is in three distinct volumes. These are connected to each other by a linking hose (pipe). The forms, as one experiences them in the space transmute into each other through the medium of this hose.

I made a drawing about thirty years ago which relates to this. It is a computer drawing of a circle changing into a square. I determined the two ends; the computer 'imagined' the rest.

It is important that you can never quite get a view of the whole piece. It is jammed into the building so as to not allow anything but a partial view. The work must maintain its mystery and never reveal its plan. Perhaps then it becomes unobtainable. I want to try to make things that remain secret.

This work forms itself between three very large steel rings, it is stretched between them rather like a flayed skin. I am concerned with the way in which the language of engineering can be turned into the language of the body.

Unlike some of my other work, this work is constructed. Its engineering is part of the form. There is a way in which the language of the structure becomes part of the language of the meaning.

Colour can be oneric. Red is a colour I have worked with a lot. I work with red because it is the colour of the physical, of the earthly, of the bodily. I want to make body into sky. This is a fundamental transformation and somewhat mysterious. The work in the Turbine Hall uses colour to form horizons which are big enough to encompass the view and bathe one in a field of colour.

I am interested in sculpture that manipulates the viewer into a specific relation with both space and time. Time, on two levels; one narratively and cinematically as a matter of the passage through the work, and the other as a literal elongation of the moment. This has to do with form and colour and the propensity of colour to induce reverie. Consequently, I hope, an elongation of time. Space is as complex, the space contained in an object must be bigger than the object which contains it. My aim is to separate the object from its object-hood.

I think of this work as a sort of descent into limbo, a sort of going below, going beneath, going underground, even though it's completely above ground. What I'm trying to deal with is a sense of disorientation, that causes one to readjust one's view, even if it's only for a minute, in order to sort of re-sight oneself in relation to the volume, in relation to the colour, et cetera. At the heart of this is darkness.

I think I've had three or four moments in my work over the last twenty-five years that have been real discoveries. The pigment pieces felt to me as if they were a discovery about an object and what an object can be; how an object can be and not be. Then, of course, the void pieces. The idea that if I empty out all the content and just make something that is an empty form, I don't empty out the content at all. The content is there in a way that's more surprising than if I tried to make a content. So, therefore, the idea that subject matter is somehow not the same as content. Then, in a different sort of way, moving from matte surfaces to shiny surfaces. In terms of the fact that the traditional sublime is the matte surface, deep and absorbing, and that the shiny might be a modern sublime, which is fully reflective, absolutely present, and returns the gaze. This feels like a new way to think about the non-objective object.

Anish Kapoor's new work will be on display at the Tate Modern
from 9 October to 23 April 2003.

Heidi Reitmaier is a freelance curator and writer, currently an arts correspondent for BBC1, and former Director of talks, ICA London and Head of Artists Projects at eyestorm media.