visual arts Gerhard Richter Anthony d'Offay, London

Gerhard Richter and Sigmar Polke are commonly regarded as the twin peaks of contemporary painting. Polke, with his discordant paintings for an incoherent age, is the recondite master of the psychic stew. Richter, on the other hand, is regarded as the steely intellect, calculated and cool, the deep one. "Richter," a leading European curator once said, "isn't a painter. He's a conceptual artist who works with paint."

For a conceptual artist, Richter does a lot of painting. His startling inventions take the entire edifice of painting, and its outworn genres, as their territory: the still-life, the portrait and the landscape, allegorical and history painting, monochromes, colour charts and gestural abstractions.

After publication of a three-volume catalogue raisonne, and with a tome of the artist's own writings and interviews about to appear in English, it seems every possible word has been said about the 63-year-old artist. The outpouring of books, catalogues, essays, magazine special issues and retrospectives, the legions of Richter imitators and his fan club of art- world philosophers do no more than footnote his talent. Everyone else may treat him as an old master, but Richter is less certain of what he's doing than his followers. Since the early 1960s, he has been unconcerned by notions of stylistic uniformity and has said he has no ideas or motifs, only motivation.

This show of more than 40 recent abstracts might almost be seen as an exercise in pushing paint around. Richter barely knows where to begin or end, applying the paint, paddling it around the canvas, then adding some more. Beginning with anything from a polite abstract "composition", or a silly bit of 1960s rainbow-hued psychedelia, Richter reworks it, adds to it, defaces it and rubs more paint into it, degrading colour with more colour. He scrapes the paint on, with a bit of board or a squeegee, then scrapes it off again. Bright skids boil up, hot lesions and dark bruises float into view and fade again.

A fascinating series of catalogue photographs annotates the stages of the painting Red, almost all of which are possible endpoints. Wild blizzards of paint came and went, and the canvas was over-worked, undermined, flayed, excavated, cancelled and radically overhauled at least 33 times before reaching its conclusion. He ends with a painting humming with hidden activity. What is troubling is not that these paintings ought to be banal, but how good and consistent they are, and how varied.

Each painting becomes an anthology of itself, of the paintings it might have become. The painting flows like a river, (River, a vast triptych, is the only painting here with an associative title) and as it passes, reflections of the places it has travelled wallow in its surface, then disappear. In Richter's paintings, what is visible is constantly changing and yet is always the same.

n At 9, 20-24 Derring St, London W1. Continues to 4 Aug