And all that jazz

The slick decadence of Art Deco spiced up the films of the Twenties and Thirties. But its effect could be sinister as well as liberating – especially in the musicals

"Nobody ever left a musical humming the scenery." Producers like to say this to rein in their extravagant designers. But in films of the late Twenties and early Thirties, scenery – of the Art Deco variety – was considered a selling point worthy of advertising. Viewers were invited to marvel at the futuristic style, which reached its apogee in the cinema. The cathedral-size ballrooms – and bedrooms – of the movies that reflected Jazz Age wildness and provided a distraction from Depression misery could exist only on a back lot, where dazzling fantasy palaces lasted until the call to strike the set.

Film and Art Deco (as a season currently being held at the Barbican shows) were linked from the beginning: The 1925 Paris exhibition that introduced the movement to the world included an exhibit devoted to the cinema. German Expressionism and surrealism, which influenced Art Deco, had long been portrayed in the movies, and mirror, that favourite material of Deco designers, could be used to great effect on the silver screen. But the style was popular for its psychological as well as its visual appeal. The slick, gleaming surfaces, the angular forms and jagged edges proclaimed Deco's rejection of the past, of anything sentimental or cosy. Tea would seem absurd in an Art Deco sitting room. You would have to have cocktails, served in slim, triangular glasses on a silver tray. The simple, short shapes of Deco dresses not only expressed but made possible the life of the newly liberated woman, out to work hard and play hard. Joan Crawford, in Our Dancing Daughters (1928), tells her man the modern woman's credo: "I want to taste life – every bit of it!" and raises a glass with the toast: "To myself!"

The fragmented forms of Art Deco also helped silent movies suggest the sound of the period – jazz. The same film begins with a close-up of a sleek, stripped-down stone figure, which dissolves into a likewise stripped Crawford (shown from the thighs down), who does the charleston while stepping into her French knickers.

The following year, in Our Modern Maidens, Joan is engaged to the rather wet-looking Douglas Fairbanks Jr (her new real-life husband – you can see from her chin why that marriage couldn't last). But that doesn't stop her trying to further her ambitions by making a play for Rod La Rocque (they had names then). Rod eventually tumbles before the ceaseless onslaught of burning glances and flashing legs – or perhaps he is simply disorientated by her house, which looks like the inside of a concertina.

Architecture, of course, plays a major part in King Kong (1933), whose co-star is the world's then tallest building, erected two years earlier. A king-size phallic symbol to match its colossal hero, the Empire State Building was topped by a mooring mast for dirigibles, then thought to be the transport of the future. The mast was used only once before the Hindenburg disaster put paid to that idea, but a masked ball in a dirigible is the highlight of Madam Satan (1930), a Cecil B DeMille movie that is desperately modern and completely insane. "Love can't be kept in cold storage," says the philandering Reginald Denny. "It's a battery that's got to be recharged every day." His wife, the elegant Kay Johnson, decides to adopt an exciting persona to win him back. In a gown that even Elizabeth Hurley might hesitate to wear, she swaggers into the orgy asking, "Who wants to go to hell with Madam Satan?"

Such pictures – Johnson walks in on her husband's girlfriend in bed with another man – stirred not only sexual passions. All this Deco decadence aroused the wrath of priests and politicians, whose threats of censorship led, in 1934, to the Production Code. It would be another 30 years before even a married couple could be shown in bed, and quite a while before an actor could say "hell" again.

But Art Deco stood for more than fast, free living and loving; this powerfully symbolic style had a sinister side. It made a good background for horror films, such as The Black Cat (1934), a very nasty piece of work in which Boris Karloff and Bela Lugosi stalk the living dead and each other through the creepily angled corridors of a chateau of horrors. The building's lack of warmth, historical reference, and personal imprint makes the terrified victim seem even more isolated.

More subtly, the gleaming hauteur of Art Deco, its agoraphobia-inducing interiors, which made it the style of choice for every contemporary MD who saw himself as Mussolini, embodied the power of the modern company or state. The genre that best exemplified this side of Art Deco was, ironically, the same one that expressed its joyous exuberance – the musical.

In the choreographer Busby Berkeley's films, platoons of dancers were transformed into identical parts in a musical machine. The festival does not include Gold Diggers of 1935, whose "Lullaby of Broadway" number crosses the line from formal to frightening – more than 100 dancers tapping like marching men, arms raised in a Nazi-style salute. But its Gold Diggers of 1933 has several sequences that illustrate Art Deco's potential for glossy dehumanisation. In "The Shadow Waltz" dozens of blonde girls in white gowns sit at white pianos in a dark room, reflected in the black glass of the floor.

In the climax, though, this reductive effect is used to protest the degradation of the average man, asked to risk his life in the First World World by a government that then abandoned him. To the song "Remember My Forgotten Man", more than 150 wretched-looking extras plodded to the dirge-like music and formed into lines to beg for bread – a rare example of this sexy style's conscription to a heartfelt message.

Art Deco Films at the Barbican continues to 5 May (0845 120 7527)