Flags of convenience

They may look just like anonymous series of stars and stripes to you but, says Andrew Graham-Dixon, Jasper Johns's repeated salutes to the Union flag reveal the artist in his true colours

Jasper Johns's Flag, 1957 could easily be mistaken for a picture of the Stars and Stripes, pure and simple, but is in fact nothing of the kind. Impure and complicated, semantically challenging and texturally ravishing, it is one of a series of works by Johns that decisively changed the course of art in America in the second half of the 20th century.

"Ceci n'est pas un pipe" Rene Magritte wrote on his painting of a pipe. Johns's epigrammatic pictures are, likewise, eternal reproofs to the literal- minded. Flag, 1957 presents the image of Old Glory and nothing but, filling the frame edge to edge just as the stars and stripes fill a real flag. But, like Magritte's illusory pipe, this is not a flag but an image.

The surface of Johns's painting is a thing of extreme, sensuous beauty. Made from pastel applied to collage, it is a field of careworn nuance. The stars twinkle in their changeable mottled patch of midnight blue. The unreliable red stripes bleed. The white stripes reveal themselves to be, on close inspection, not stripes at all but squeezed bands of cursive hatch and scribble, misty and atmospheric.

During the past 40 years, Johns has painted some 90 versions of the American flag. Twenty-five of them are currently on display at the Anthony d'Offay Gallery in London. The exhibition begins with Flag, 1955, a work on paper executed in graphite pencil and lighter fluid, and concludes with Flag, 1994, in acrylic on canvas. "Using the design of the flag took care of a great deal for me because I didn't have to design it," Johns once said. He added that he liked to paint "things the mind already knows. That gives me room to work on other levels." Often, there is an abnormal radiance to the rectangle that contains the stars, and the stripes have been rendered a little wonkily, so that they may, to some, seem to hover and vibrate.

In New York in 1954, when Johns first started painting the American flag, he was an anomaly. The majority of famous American artists in the 1940s and 1950s had dealt in grandiloquent gestures of self-invention and self- annihilation. But Johns disliked the idea of invention altogether, and preferred self-effacement to the boozy, romantic self-destructiveness of so many of his elders. Johns's paintings were small and restrained. His chosen motif was not dredged, messily, from the depths of his soul. It was impersonal.

Johns changed the life of the American artist as well as changing American art. His stance of cool and suave irony presaged an end to acts of striving, romantic heroism in the lofts of bohemian Manhattan. His painting inaugurated a new aesthetic, and its influence lay behind the evolution of new movements in art. Johns's serially repeated flag became Andy Warhol's serially repeated Coca-Cola bottle, or Marilyn, or Elvis. Johns's dandyish relish in the minutest inflections of paint, and his love of that special, modulated dumbness made possible by the act of forever painting the same dumb pattern, were also full of hints and portents. They may be seen, with hindsight, to have predicted the advent of Minimalist art, and the consequent apotheosis of the exquisite nearly-nothing-at-all.

The question that has always hovered over Johns's flag paintings seems likely to remain the same. Why, when there are so many things in the world to paint, would someone want to paint something as unrelievedly banal and dull as a flag? Various answers have been suggested, of which patriotism is certainly the least plausible. Johns's decision to paint flags was original, but it was also full of nostalgia for the working conditions of artists in the past. Picasso used to complain that it was the curse of the modern artist to have to invent everything - himself, and his subject matter - from scratch. By painting a flag, something "the mind already knows", Johns was taking a great leap backwards in time. Precisely because his subject was a given, precisely because it was as commonplace as, say, The Annunciation or The Madonna with Child had once been, it relieved the artist of the burdensome and tedious task of devising a theme for himself.

Part of the cleverness of the device lay in the fact that it instantly provided Johns with his subject and therefore enabled him to begin his career at a point which it takes most modern artists half a lifetime to reach. Having dealt at a stroke with the what of art, he could get on with the how. Johns himself, in many different modes of feeling, may constantly be glimpsed in the interplay between the two. He has painted the American flag like a jazz band might play Ain't Misbehavin'. The theme has been a pretext for the variations played upon it.

Anne Seymour, author of one of the two essays in the exhibition catalogue, industriously notes the variousness of those variations: "They range from tiny monochrome graphite drawings, through small paintings on various surfaces from brown paper to silk, to large paintings five or six feet long and occasionally even bigger. There are flags in textured pastel and flags with collage. Some are painted above white spaces, others on coloured grounds. There are flags in ink wash on plastic. There are black- and-white flags and grey flags, green flags and flags on orange fields. Throughout the years there is an even sprinkling of flags in their original livery, but there are also silent muffling white flags more like the substance of light than the divisions of colour, a six-foot double flag like a Monet waterlily painting, a bronze flag, a silver flag... There are single flags and double flags and triple flags laid one on top of the other, flags which are turned sideways and flags which are seen from the back."

This nearly Linnaean taxonomy of species gets to the heart of Johns's achievement in painting these perverse but brilliant pictures. The same thing, painted again and again, yields swarming worlds of sight and feeling. Johns's smallest and most intricately worked flags, which are drawn in pencil, are the most romantic of all his imaginings. The hatched pencil marks form tangled, twilit thickets, dark woods in which to get lost, in which to be tempted, in which to fall asleep for a hundred years. In some drawn flags, the marks are spread even more lightly, like fine grass clippings, a texture so subtle that it almost conjures the sound the pencil made in forming it. These are like whispers or susurrations made tangible. Johns also creates flags like walls, collaged newsprint peeping through the image and evoking palimpsest of flyposter. He paints distressed flags in fag-ash grey, their stars a mockery of dreams, their stripes like the dirty, empty streets of some abandoned, worn-out city. His white flag is a world in outline and contour only, after a sudden deep snowfall. In the middle of Flag, 1983 - a picture painted in the regular colours of the Stars and Stripes - a single drop of white paint has been allowed to run down the face of the picture like a surprising teardrop.

Why did Johns paint flags? For the same reason that Giorgio Morandi painted ordinary tables cluttered with ordinary bottles and vases. The mundane, banal subject provided him with a discipline and a shape, as well as a check on his own unruly emotions. Johns's later flag paintings seem on occasion terribly morbid. Flag, 1994 is an almost obliterated flag, a picture formed of opaque patches of dark paint over scribbled drawing, with a bloomless skin. But because it is, still, a painting of a flag - another variation on that same cool, flat theme - it is held at the edge of sentimentality, restrained from the plunge into old-man portentousness.

David Sylvester, who was one of the first critics to write perceptively about Johns in this country, has contributed a fine, sad essay about the flags to the catalogue of the exhibition. He understands these pictures as well as anyone in the world except, perhaps, Johns himself, and the last paragraph of his essay is certainly the wisest and most honest piece of art criticism I have read in a long time:

"The marks shape the matter on the surface so that it becomes an objective correlative of subjective experiences - say, looking while focusing, looking without focusing, looking out of windows, looking at light or darkness, seeing things grow or wilt, seeing things change through disease, seeing the passing of the seasons, feeling threatened, feeling alone, feeling calm, feeling deaf, feeling elated, feeling tears at the backs of one's eyes. The marks build a surface that embodies an accumulation of sensations and feelings that have come and gone."

To 27 July, Anthony d'Offay Gallery, Dering Street, London W1 (0171- 499 4100)