The incredible lightness of colour

Stephen Cullen is not afraid of colour. His paintings, at the Hallward Gallery, positively blaze with thick expanses of brilliant reds and yellows. The customised frames often follow suit. On the whole, painters are pretty careful about colour, wisely treating it like a high explosive that might go off at any moment and must be handled accordingly. If you see someone throwing primary colours around with kindergarten abandon, you can be reasonably sure they haven't really thought about it and learned how to use it. It's one thing not to be afraid of it, quite another to have a colour sense. Yet despite lashing on garish colours so freely, and despite the occasional lapse, Cullen does have a real colour sense. Just when things seems to be getting out of control he'll throw in a strategically placed note of calm. A work may be almost incandescent, most of its surface pure scarlet, but the scarlet will be part of a scheme that works harmoniously.

Born in 1959, he worked as a commercial artist for a Dublin advertising agency prior to becoming a full-time painter in 1982. His pictures are nominally representational. The titles suggest subjects like figures, landscapes or small, anecdotal recollections, but in the event these ostensible subjects are really occasions for the use of colour.

When he paints a figure, it becomes a big mass of red, or blue, or pink. In Walking the Dog, for example, the dog walker becomes inflated to the point where he or she is a big red barrage balloon that dominates the composition almost to the exclusion of everything else. Usually the subject is indicated by just a few lines incised into the surface. Much of this - the bold colours, the deliberately rudimentary drawing, the dramatic expressiveness - recalls European painters of the 1960s, particularly Karel Appel and Asger Jorn, even Jean Dubuffet. But there's also something about the work that's entirely Cullen.

Aoife Harrington, at the Rubicon, is a much cagier painter. In all of her work she restricts herself more or less to variations of muted, greeny ochre. Each individual painting is from a series called Penumbra. Generally in painting the term refers to the area where light and shade meet and mingle, and Harrington explores the borderline where the subject is differentiated from the ground. There is just one motif, a symmetrical vessel shape, and it is picked out against the background with a variety of tonal and textural effects.

??????LIShe has made quiet, understated paintings infused with soft, subtle light. They are not minimalist in the obvious sense, but all the same they do strive to cut painterly language down to a minimum number of elements yet still allow expressive possibility. It's not quite clear, however, that the finished works make a strong enough case for just this particular motif, just this colour range.

Olivia Musgrave's sculpture and drawings, at Jorgensen Fine Art, align themselves very much with a classical tradition. Her indebtedness to the 20th century classicism of Marino Marini and Giacomo Manzu and her penchant for mythological subjects is appropriate given her mixed Irish and Greek parentage, and much time spent in Italy. Marini more or less reinvented the horse and rider theme and made it his own, but Musgrave succeeds in devising some successful variations with a series of Amazons on horseback. A strong vein of humour and a certain related sexiness are allowed some latitude in her work, but traditional sculptural values hold sway. Her forms are thoughtfully modelled and have great weight, balance and presence. Even her humble Sheep, a mundane subject, is done with great verve.

Lindy Guinness, showing at the Solomon Gallery, also works from a solidly traditional base. In her case, it is 20th century British representational painting. She once attended Kokoschka's Summer School in Salzburg, but she's more at home with the muted colours, tonal values and strong compositional structure of such English exemplars as William Coldstream and Lawrence Gowing. And she brings these qualities to bear very effectively on the landscape of the West and Northwest, as well as around her home at Clandeboye.

Her sober studies of the rocky Atlantic Seaboard are heavily schematic in a Euston Road sort of way, but the approach is appropriate because The Burren and the Aran Islands are extremely structured landscapes. She is also, it must be said, scrupulously attentive to the details of light and texture. Restrained colours, lots of mid-tones and a preoccupation with measurement can engender a certain dullness, but in truth the pictures aren't dull. In Lock Salt, Donegal, for example, a fairly austere little study, she's made a real, richly atmospheric gem. There are, though, too many paintings in the show. The still lifes seem less convincing, and the works from Yemen and Morocco, though they have their moments, are more uneven.

Tony Crosbie's work at the Jo Rain Gallery, under the title City of Defeated Angels, sets out to embody the artist's feelings about the level of homelessness he observed on a trip to London, and the way it was casually accepted. He uses a variety of discarded materials in a series of violently expressionist painted constructions. The problem is that they keep telling us that they're wearing their heart on their sleeve. There is a certain raw energy about them that looks promising, but they are handicapped by a jarringly heavy-handed symbolism. If he was going to editorialise so explicitly, he didn't need to make the pieces.

If you want to see an exhibition but working your way through a gallery full of art seems a bit too much like hard work, there is an alternative. Joe McGill specialises in visual and verbal puns. The first work he has exhibited here in two years can be seen at Beak, 4 Crow Street (not a bad pun it itself). A brief statement reveals that "it is an installation of objects found in an Oslo hotel room," though the plural "objects" is overstating the case. There is an object, and a line. It's called Reflection. Any further description would give the game away, because it is a one-liner in that sense as well, but it is as minimally self-cancelling as anything he's done to date.