Franz Kline's incommunicativeness on the subject of Franz Kline may have contributed to the slow decline of his reputation since his premature death, from heart failure, at the age of 51. Once regarded as one of the leading Abstract Expressionists, his work has subsequently fallen into neglect, partly because of his reluctance to back it up with statements of intent. Mark Rothko and Jackson Pollock, his more celebrated contemporaries, explicitly described the ambitions that lay behind their canvases - and by doing so they helped to create a set of terms, and a framework of ideas and values, within which Abstract Expressionist art has more or less ever since been discussed. But their goals were not Kline's goals, and his paintings make no sense at all when they are measured by the standards appropriate to the paintings of more famous Abstract Expressionists.
Kline makes no attempt to conjure the transcendentally charged voids of Rothko. He is equally uninterested in the cosmic metaphorical possibilities of abstract painterly gesture which so preoccupied Jackson Pollock. His is an art charged with a dark, heavy, sullen materiality: an art of and for the city, New York, that was both his adopted home - he had been born, in 1910, in a steel town in Pennsylvania - and his most enduring theme. Kline was not perhaps, in the end, as great an artist as either Pollock or Rothko, but he was a considerable one, and the time is right to rescue his work from the relative oblivion to which art history has, in recent years, consigned it.
All of which makes the Whitechapel's current show, 'Franz Kline: Art and the Structure of Identity', both a brave and salutary exhibition. The Whitechapel has been historically more sympathetic to the art of the New York painters of the 1950s than any other British art institution, and it is good to see it remembering its own past in this way. Kline's art has not entirely sunk from view, and Lesley Waddington has periodically included fine examples of his broad-shouldered and muscular painting in his shows from gallery stock in Cork Street - one of those small but important gestures of fidelity for which commercial dealers are insufficiently credited. But not since Bryan Robertson staged what sadly turned out to be a memorial exhibition of Kline's work, at the Whitechapel in 1964, has his work been shown in any depth in this country.
This is a show that will surprise many of those who know Kline's work, primarily, from pictures in books. Kline's paintings, like all paintings and most especially like all New York School paintings, are thoroughly denatured by reproduction. In reproduction, their scale, which is so important to their effects, is entirely lost. But so, too, is the sometimes subtle heaviness and the constant hesitancy of Kline's handling. The comparison that has frequently been drawn between his brushstrokes and the free, loose spontaneity of oriental calligraphy is convincing only superficially and only when his pictures are seen in reproduction. In reality, the marks that Kline made on his canvases, applied with thick housepainter's brushes, are anything but spontaneous. His pictures are slow, not fast: things that have been painstakingly constructed, not conceived in the mind's eye and executed with the swiftness of thought. The heaviness of Kline's black girders and joists and I-beams, built in layers and then feathered into white pictorial voids, gives his pictures their most powerful quality, which is fundamentally architectural. Kline paints a picture with something of the stubborn, improvisational character of an amateur carpenter building a house.
This heavy, built quality in Kline's painting has made him one of the unacknowledged heroes of what might be termed a distinctively American blue-collar aesthetic: an aesthetic which, although it has tended to produce works of art commonly referred to as abstract, is much more interested in realities than abstractions. Kline's dark blocks of paint, his scaffolding traceries, his asphalt highways - these link him, not to Pollock or Rothko, but more closely to a tradition of constructed American sculpture initiated by David Smith and continued today, albeit in a very different vein, by Richard Serra, whose huge constructions of rusting sheet-steel, full of a distinctly American sense of the grandeur of American heavy industry, often look like Klines made solid and three-dimensional.
Although Kline's pictures are abstract they are shot through with a powerful sense of place and, at their best, they look like stunned memories of those towering monuments that are the bridges and skyscrapers of New York. Palladio, with its huge heavy black forms rushed into indistinctness by some of Kline's most flurried, excited painting, is like a recollection of New York as seen from a speeding car or through the windows of an elevated train. There may be a kind of jingoism behind that title: Kline's way of saying that the old architectural innovativeness of Europe, embodied in the buildings produced by that ancient tradition inherited and passed on by Palladio, has migrated to America. Meryon, the most impressive of all the pictures in the Whitechapel exhibition, is the Brooklyn Bridge reconfigured, rebuilt in paint and, in the process, reconceived as a symbol: an emblem, in its powerful thrust of great engineered shapes into cloudy whiteness, of nothing less than the vast energies and equally vast aspirations of a new and newly self-confident American nation.
Kline was a deeply uneven artist and as this show progresses he seems to lose much of his sense of direction and purpose, complicating his pictures unnecessarily, sabotaging the talent for starkness and simplicity that was his chief gift by introducing a new and broader range of colours into his previously ascetic palette of blacks and whites. This was a mistake, partly because Kline was such a poor, muddy and confused colourist. But his finest works are unique, precious embodiments of the spirit not just of their maker but also of their times. Kline was the master-builder of Abstract Expressionism; and what he built, from blocks and beams of paint as dark and heavy as industrial steel, was a new and, in its way, heroic style of American art.
To 11 September at the Whitechapel Art Gallery, London E1 (071-377 0107)