Norman Rockwell's America – review

There is a self-portrait in this terrific survey that shows Norman Rockwell seated before a large canvas. He holds a paint-loaded palette and numerous brushes. Tacked to the canvas are exemplary self-portraits by Dürer, Rembrandt and Van Gogh, pin-ups for this humble acolyte, lanky and stoop-shouldered, who attempts to portray himself in the old tradition.

But look again. The face on the canvas is emerging as a pencil sketch, not an oil painting: a drawing of Norman Normal, as he was joshingly known. Rockwell has used paint to imitate pencil; down below, his name is lettered in upper and lower case, just as it appeared on the Saturday Evening Post covers that made him America's favourite 20th-century artist.

Right down to the printed "signature", in fact, the self-portrait on the canvas is turning into a cover.

It is a sweet but sad conceit, Rockwell's modest way of showing his readers that he was actually a painter. For most people thought he produced pictures, not paintings, and many still do, downgrading Rockwell's popular art to nothing more than sentimental picture-making.

At Dulwich, where the large 1960 self-portrait appears miniaturised as a cover image, the picture-painting distinction is very vividly experienced. The show includes all 323 of the covers Rockwell produced for the Post over 50 years and many other magazine and advertising images. But it also presents 40 of his oil paintings.

Startlingly large, with their inner warmth working up from vermilion and Mars violet, they immediately give a sense of Rockwell's deep knowledge of art. With a few Rembrandt scumbles, white on white, he describes grass without actual depiction. The suave gleam of polished leather is learned from Velázquez. From tufted carpets to tartan plaid, there are hints of Van Eyck everywhere in the exacting plenitude of surface detail.

Each painting is exceptionally well-made, from the bone and muscle beneath the skin of a sprinting boy to the careful shadows and flawless perspective that make Shuffleton's Barbershop – the band viewed through the darkened shop, playing forever in the glowing backroom – look like modernised 17th-century Dutch painting.

Rockwell, when asked, spoke of himself as an illustrator rather more than a painter. The artists of his era pioneered cubism, futurism, abstract expressionism; he had been to Paris to try it out, unsuccessfully he said, before returning home to good old representation.

His was an America of soda-fountains, proms and mountainous Thanksgiving turkeys, of avuncular cops, twinkly grandpas, young love and long marriage. Not the kind of thing Picasso painted and nothing the critics would admire – "the Rembrandt of Punkin Crick" sneered the New York Times – until Rockwell's critical reputation soared in the 90s. By then, though, he had been steadily adored by millions of Post readers, as well as Roosevelt and Kennedy, Updike, Warhol and de Kooning among many others. His view of life excluded the sordid and ugly, he said, because: "I paint life as I would like it to be."

The boy racing alongside his fireman hero towards the ominous glow that lights their faces, the honest grocer carefully measuring out the sliced ham, the travelling salesman shedding collar, tie and all for a secret dip in the creek. Rockwell has a perfect instinct for characters, but also for American icons. His Rosie the Riveter may draw graphic strength from Michelangelo's Isaiah, but her kerchiefed personality is all her own. Willie Gillis coming home from war, equal to anything in Frank Capra, is Rockwell's great Everyman.

Cheerful, tolerant, sympathetic to all (or nearly all) of society, starting early, working late every day until his death in the saddle, Rockwell himself seems to exemplify the American virtues he portrays. No wonder the country loves him, a cynic might argue; no wonder Steven Spielberg and George Lucas collect him. He is all about making the dream look real, selling the best possible version of America back to America. But Rockwell's is not an art of realism. His images announce themselves as artifice straightaway, and not just because they are self-evidently painted.

Almost every image takes the form of a vignette, a moment floating free of time and place, a self-contained truth. And this is emphasised, over and again, by graphic abstractions – a silver circle, a free-floating scarlet disc, a black frame or a pure white background against which the whiplash silhouettes appear indelibly crisp.

Rockwell is famed, even among detractors, for his social observation. But what he saw is never the same as what he made of it. For one thing, all facial expressions are held at their most extreme – squinting and sighing and beaming and frowning. For another, his figures are not quite of this world, being more classically proportioned than anything in life; they are people from (and of) art.

It seems to me that Rockwell had two different talents. As an illustrator, he was second to none. Look at his April Fool cover with its 60 different jokes, including a tiny – haloed – Mona Lisa tucked in one corner. Cinema tickets, pub signs, photographs, playing cards, posters, he could pastiche and condense any form of graphic art, what's more, within his own.

But as a painter, his ideas are more purely expressed. In a canvas like Charwomen in Theater, in which two cleaners pore over the programme in the dead yellow gloom of the empty auditorium, the raked light and solid shadow between which they seem to slip is as poignant as anything in Edward Hopper.

Rockwell is typically attacked for his lack of a downside. Why aren't there more segregated blacks or persecuted communists in his art? Because the Post did not allow it. He parted company with the magazine in the 60s when it sank into the celebrity mire, longing instead to paint "pictures of civil rights, astronauts, poverty programmes…" They are his least successful works of art.

For Rockwell's gift is for the small but resonant truth. Look at After the Party, where the elderly woman, bathed in kindly lamplight, listens to the young girl's avid account of her evening. Who hasn't felt that need to confide, to tell the story in order to make it real? Montaigne writes of it; Rockwell depicts it. Why is the latter to be despised?

The self-portrait, so full of nuance and comic deflation, sums him up as both man and artist. It shows him from behind: what he really is we do not know. Norman Rockwell portrays himself as a plain guy in sensible shoes and chinos, modest, anonymous, as ordinary as the next man – as ordinary, and as complex.