Anna Barriball

Entering Anna Barriball's show, one saw a crinkled silver sheet under glass. Folded into rectangles and then unfurled but not smoothed out, Silver Map (2003) is an irregular terrain of valleys and peaks. The silver surface reflects the light unevenly, prolonging the time it takes to recognize what we're looking at. Eventually, close up, it's clear that this sheet is a world map wallchart. Closer still, we see it is a geological map representing rivers and mountains with different shaded inks.

So, nose to the glass, the work unfurls. We reconstruct the process in the opposite direction to the way we encountered the drawing: Barriball started with a map, one that described the bumpy surface of the planet. She smoothed it out with the even flow of the silver pen, and then, treating this sheet not as a wallchart but as a pocket map, trumped the starting material by transforming the sheet into a real surface with proper ridges. The drawing plays out a dynamics of exchange - surface for image, reflectivity for information. It's easy to forget that the delicacy of ideas had to be matched by care with materials: the silver needed to be thick enough to cover the map but thin enough to allow it to show through.

Barriball's works may appear slight at first, but their complexities soon unfold. There's a poetics of reversal and contradiction: to conceal is to reveal; transparency produces obscurity; the border between inside and outside is undone. Drawing, her most successful medium, was once privileged for its purchase on the immediate and clear expression of artistic thought, but here it becomes more twisted. Window (2002), for instance, was made by84 simply rubbing a pencil over a bumpy bathroom window. Barriball worked on top of a translucent surface to produce one that is opaque. It is also dense and reptilian. In fact, it's utterly scrumptious, and once we register this, another reversal becomes apparent - bathroom windows obscure the naked body to shut out desire and shame, and from this sexless starting point Barriball conjures sensuousness.

One of Barriball's consistent concerns is to produce artworks that can somehow contain their opposite, that court contradiction. Another is to make static works in which multiple layers of time are compressed. One room has a series of seven drawings made by hurling a graphite-covered rubber ball against a sheet of paper. The moment of impact is registered by a surprisingly regular circle where the squashed surface of the ball has come into contact with the paper, a circle the width of which depends on the strength of the hit. The drawings are titled after the exact time of the impact - 18:50:17 (2002), for example - but their surfaces suggest a more attenuated temporality. For all around this circle are scatterings of graphite powder, sprayed out before and after impact as the ball hurtled towards the paper and bounced away from it. Three layers of time are condensed in the cosmic-looking image, which, for all its scientific pretence, the title can't explain. And in any case, how did the artist know or measure the exact second of the hit?

Another room contained wax drawings titled not with instants but with durations - 9 hours and 14 minutes (2003), 9 hours and 7 minutes (2003). Each is a polychrome grid of uneven wax spots. Barriball had arranged nine candles on a sheet and, after lighting them, had watched while they burnt down. The artist gazing into her coloured candlelight - it's a nice picture but, for all its prettiness, in the final works the residues of the candles are bumpy waxen stains whose colour is dirtied with sooty spots. The title suggests a time of long contemplation, but there are signs here of distraction: one candle burnt through the paper. For an inveterate fidgeter such as myself, while the works are records of the past they are also naggingly present - there's an insistent urge to pick off the wax, (and it's a marvel that the artist didn't).

The economy of Barriball's work can be utterly out of proportion to the wealth of its effects, but there are times when one wonders if the terrain in which she operates is not a little overpopulated. The candle works recall Ceal Floyer's 1999 'Ink on Paper' drawings, and the rubber ball pieces bring to mind Dave Hammons' recent show at White Cube, where by bouncing a basketball against the walls the artist entwined a poetics of markings and time with a subtle cultural politics. This familiarity seems most acute in Barriball's work in Black Wardrobe (2003). The cupboard is dense and disguised, wrapped so tightly with a continuous coil of black gaffer tape as to tempt one to forget that its door could ever have opened. But however it is haunted by the secrets of its former use, the ghosts of Rachel Whiteread and Doris Salcedo are here too. All this is to say that, while Barriball's interests in conceptual reversals and temporal compression are refreshing, especially given a wider context where drawing so often means illustration, her motifs are occasionally too familiar for this language to take full effect.