Nancy Rubins

It hardly seems possible that there could be any American art stars whose names are still unknown over here, but so it seems with the California-based sculptor Nancy Rubins. Her spectacular works – gravity-defying assemblages welded out of aeroplane wings, car parts and even canoes – spiral dramatically upwards in front of museums from New York to LA. There is a strange grace to these towering propositions, which have found permanent homes across the globe but never here. Astonishingly, this is her first solo British show.

You look up, in the gallery, at this jaw-dropping sight: a ship created entirely out of metal beasts strung together with high-tensile rigging. Silver wolves soar like sails above a tumult of black boars and the hard shells of old turtles inverted into a hull at the bottom. These cast-iron creatures radiate from a welded mass at the centre; steel cordons running through eyes, tails and noses somehow holding the whole conglomerate aloft. Heraldic beasts on a voyage to nowhere, Darwin turned upside down, or something quite else? Rubins lights a fuse of slow-burning thoughts.

Zebras, tigers and giraffes mound up into another colossal form, an ibis jutting from the tip like a masthead. There are overtones of empire. Hidden in a nearby work, like a game, is what looks like an actual crocodile. The creatures get bigger as the sequence evolves, the turtles turning giant. A dark horse dangles high off the side of a real cliffhanger of a sculpture.

After the awe comes the obvious question, which is how the medium relates to the form. And this is most curious and bewildering. For close inspection reveals that these animals are in fact expensive garden ornaments – the steel wolf, the bronze giraffe – of the sort that decorate the lawns of Pacific Palisades and Malibu. No doubt the social resonances will be different in Los Angeles than in London, but still there is this mild shock of realisation. One saw them as animals first, but now they are industrial objects, mass-produced chunks of metal.

And then – Rubins’s art grows slowly as crystals in the mind – one starts to lose sight of these objects as figurative. They become more like elements in an abstract sculpture; except that these twisting forms also resemble plant growth – old oaks or jungly philodendron (sure enough there is a curlicued crocodile tail disappearing through one, so perhaps flora and fauna are matched). The effects just continue to proliferate.

In the past, Rubins’s sculptures have been quick hits: forms that appear to explode, take flight or crash down abruptly. Now she is in her mid-60s, they seem grander and more pensive. They are part of a long tradition of heavy-metal US sculpture, from John Chamberlain’s crushed cars to Bruce Nauman’s revolving carousel of critters. And there is a sly play on Richard Serra’s famous molten-lead splashes in the glowering sheets of dark lead, twisted and emblazoned across the walls like violent thunder claps, which turn out to be made out of pencilled paper.

This feels emblematic of Rubins’s art in general: heavy yet lightsome. The scales, feathers and matted fur of her beasts have affinities with foliage; her great ships are like trees; lead can be upstaged by paper. Her biggest works tower above you, yet you can get nose-deep among their elements and appreciate the comic arrangements of nuts, bolts and paws. And nobody could fail to notice the inherent absurdity of recycling kitsch critters into post-abstract sculptures. This is late-flowering surrealism at its best: brute metal arranged with all the finesse of a bouquet.

Rubins’s fellow American sculptor Craig Kauffman (1932-2010) is equally unfamiliar to British audiences, which may be why Sprüth Magers has chosen to prop him up between two of his more famous minimalist friends, Donald Judd and Robert Morris. But Kauffman doesn’t need their support. Cast in vacuum-formed plastic, often using household objects as moulds (think of Rachel Whiteread, decades later), his sculptures are radiantly beautiful.

A rectangle of transparent Plexiglas, phasing from deep pink to golden yellow, hangs like a towel on a rail. Light passing through it leaves a shimmering copy on the wall; two Rothkos, as it were, parodied to delight. A glass frame dabbed with luminous touches of copper, blue and cerise looks like a postmodern Seurat. A great rectangle of shining red, puckered in the middle, invites you to kiss it full on the lips.

These are not the invitations of classic noli-me-tangere minimalism, where the merest fingerprint might mar the pristine blank surface. Kauffman was clearly a gleeful man, a California surfer more than a New York intellectual like Judd. Included here is a flier from 1970 where he offers to make any kind of sculpture – no project too small or too large – for 25 bucks an hour with his friend Robert Morris.

Upstairs, in contrast to a pair of Morris’s felt works, severe grey strips disposed against the wall to investigate the effects of gravity, are Kauffman’s sensuously undulating painting-cum-sculptures. A vanilla-coloured rectangle with rippling outlines in butter and caramel could be the hood of some fantastic west coast car or an edible artwork just asking to be consumed with more than the eyes. Perhaps Kauffman’s art was too joyous for the movement to which it supposedly belongs, for he has rarely been shown here since the 60s. So there is another excuse, if one were needed, not to miss this show.