An artist is at a distinct disadvantage when it comes to depicting a building: the problem is that the architect has got there before him. A show in Manchester reveals how two British painters have tackled the challenge

Buildings and walls have a privileged place in European art. The beginning of perspective was a picture of a building. Brunelleschi made an image of the Florence Baptistry to demonstrate the new pictorial system. Leonardo, on the other hand, recommended walls and the random damp patches on them as an inspiration to pictorial inventiveness. One is a model of discipline and accuracy; the other a model of freedom.

"Urbasuburba", an exhibition at the Whitworth Gallery in Manchester, is full of pictures of buildings and messy walls, among other things. It's a two-man show - two British artists in their forties: Jock McFadyen (who does the urban side of it) and Humphrey Ocean (the suburban). They're both realist painters, and their painting undertakes the basic representational enterprise, asking and answering the recurring question: how's that to be done, then? How's that bit of the world to be translated into paint?

I'm going to dwell mainly on Jock McFadyen's work, because I think his questions and answers are more interesting.

One thing that McFadyen's been painting in the past couple of years is a series of big pictures of disused or dilapidated East London properties, either functional (a factory) or entertainment venues with makeshift 1930s grandeur (a bingo hall, a snooker centre, a cinema). He paints them full- frontal, square-on, so that the oblong facades nearly fill the canvas and largely determine its composition. And he's been painting walls, specifically the walls of unrenovated London Underground stations, complete with peeling paint, grimy posters and deep, ancestral soot.

It sounds rather like a photographic project, the sort of series-on- a-theme that photographers deal in. But both these subjects confront painting with a particular problem. Both of them are, in a way, second- hand subjects. The thing about buildings is, someone else has done the picture already - the architect.

The painter is anticipated by the architect's designs and compositions. Whatever the painting adds or transforms, it must follow and compete with the architectural plan. And the thing about messy walls is, they too are prefab pictures - found abstractions, already artistic, with chance effects that tend to out-flank the most free-spirited brushwork. These are new topics for McFadyen.

Urban ruin has always been his business, but previously he's been mainly a figurative painter, a flesh-painter, dwelling on the bodies and faces of the damaged and the derelict. There are some examples in this show too. The figures are painted in a kind of caricature, with this big difference: in a normal caricature, the figures don't feel their distortion, but McFadyen's people do. It's a strange flesh - laid on them in strands of paint, sometimes raw and tender, sometimes numb and sluggish - that they find themselves stuck in. They're people who've grown into their wounds. But while this is the kind of powerful treatment you can give human figures, it's not the kind you can easily give to buildings (too solid) and messy walls (too fluid). These subjects leave his painting more exposed and on its mettle.

And what's good about a picture like Kennington - which shows one of those chaotic, transitional bits of wall where the station ends and the tunnel begins, with jumbles of wires and pipes - is the way it keeps so flexibly responsive to each representational task. Faced with this almost meaningless motif, it doesn't impose solutions. True, you can find traces of McFadyen's "handwriting" in the rather off-hand fluency with which the wires are streaked in. But with the expanse of yellow paintwork, peeling, cracking and smudged with filth, which takes up most of the picture and which the picture has to render with its own paint, there's no style statement. The painting doesn't simply respond with random mess-techniques of its own (though clearly a good deal of smudging, smearing and pooling has been used); nor with tidied up, decorative effects. It stays attentive for all the differences in texture. There are passages where you can't tell, and the picture doesn't decide, what's going on exactly (where does deep, black dirt turn into a hole in the wall?).

The building pictures aren't always so responsive. Dilapidation and stains give something to work on. What often happens is that the shapes of the architecture provide fixed grid-lines - there isn't a lot that can be done with the basic structures - between which the painting tends to become fill-in of one sort or another.

This move into buildings and walls points to something that has been a going concern in McFadyen's work for some time: his attraction to "second-hand" motifs in general. Graffiti, for example.

Humphrey Ocean's work is quite different. He renders suburban houses and motor-bikes and transistor-radios with a pristine detail and neatness - like someone who believes the architect's prospectus and the manufacturer's brochure; or is it meant to dramatise the sensibility of product-proud suburbia?

And then these neat bits are varied with passages of rather arty free painterliness which I don't get the point of. As a case for the painter's translating hand, it's not so strong.

McFadyen's work is the best way of preserving the rot.

To 2 Nov. 0161-275 7450