Kienholz: The Hoerengracht

Commerce has long exploited this propensity to voyeurism via shop window displays. But in Amsterdam's red light district the goods in the windows are human beings, the service on offer is sex.

This is the shocking subject of the Hoerengracht (1983-1988), now exhibited in London's National Gallery.

Impatient with the limitations of traditional art as a means of communicating ideas, in the early 1960s, Ed Kienholz (1927-1994) pioneered free-standing installations through which he exposed social taboos in the US such as prostitution, illegal abortion and inhumane mental institutions.

He later collaborated with his wife Nancy Reddin (b. 1943) and since 1982 they credited their work to the single name Kienholz.

The Hoerengracht's title is a play on words.

Literally it means "whores canal" but this is also an ironic reference to the Herengracht ("gentleman's canal"), a rich district of Amsterdam which contains a lesser-known red light district than the famous one situated in the working-class district.

The installation recreates but also transforms a life-size section of the latter's tiny houses and narrow streets.

Created from real objects including doors, furniture and knick-knacks bought in Amsterdam's flea market, it houses representations of 11 prostitutes.

Made from life-casts of real women, the figures are naturalistic and individualised in shape, posture and attire.

One sits reading, her dog snuggled beneath her feet, another turns her back to us, one crouches on the stairs, another shivers outdoors, huddled in boucle jacket and hat, her ankle boots swept by autumn leaves. Most are indoors clad in revealing underwear.

But their heads are those of shop window dummies bewigged and heavily made-up.

The contrast of these artificial, idealised faces with their unseeing gaze atop naturalistic bodies is disconcerting, a disjuncture further emphasised by the metal-rimmed glass display boxes which encase their heads.

The more we experience this work, the more its juxtaposition of the real with the unreal becomes apparent.

The sound from the tinny radio distorts the music we hear.

The women's minuscule rooms are filled with authentic furniture and domestic paraphernalia - ashtrays, pictures, a coat hanger.

Yet some of these are partially obliterated - a wallpaper with hearts and the word "darling" as its motif has been savagely smeared with paint which drips like tears across the hollow words.

Far from being lifelike, the surface of the figures' flesh has been varnished so that it glistens like that on saints' statues in old-fashioned churches.

Moreover, a transparent resin has been dribbled and spread over entire surfaces.

Visually unifying the diverse elements of the work, it also conveys contradictory meanings.

Its rivulets down a window evoke the gloom of rain yet the droplets also glisten like pearls - dribbled across a mannequin's lips and chin it evokes tears but also semen.

Set in a darkened room, the work twinkles with a multitude of light sources.

Indoor lights against outdoor gloom, red, blue and green light bulbs and neon tubes, liquid fairy lights dance across window frames, an ultraviolet light throws its sickly glare across a seedy stair case, a naked light bulb in an attic illuminates a laundry line.

The lights bounce off and reflect from the many mirrors, glass and varnished surfaces. The visual seduction of the textures and surfaces caught in this cross-fire of differing and changing lights opposes the horror of the subject matter.

Peering into windows we turn down a dark alleyway only to meet other visitors coming round the corner so that we are cast into the role of embarrassed punters, and this is emphasised by a life-size photograph at one end of a man in a raincoat hurrying towards us, perhaps a client or maybe a curious tourist. Like us.

By contrasting the real with the unreal, Kienholz transmutes the subject into a work with multi-layered implications.

Complexity and directness co-exist, it is both seductive and repellant.

The women are portrayed sympathetically yet Kienholz implies a critique of their situation by casting the viewer as voyeur.

The strongest impression is one of sadness. Tear-stained or impassive, these mannequins' gazes refuse to answer ours.

Seemingly unseeing they protect themselves by shutting down all emotion while their bodies and cosy rooms invite seduction.

The effect is sharpened by the work being displayed incongruously in the National Gallery, so that we step from high rooms hung with clearly lit mythological and biblical paintings into the darkened sleaze of the Hoerengracht.

The transaction of money for sexual services exemplifies the most extreme form of capitalism's commodification of human relations.

This work may embarrass, anger, sadden or disgust. In doing so it forces us to confront our moral and political stance about an unpalatable but actual social reality.

Runs until February 21, admission free.