The campaign to get women the vote was one of the first political movements to take place in a fully seeing age. Heroic images of a tiny Mrs Pankhurst being lifted off the ground by policemen, or rows of classical-looking girls hooped with WSPU sashes, have become stock stand-ins for a narrative that was actually lengthy, episodic and often dull (try slogging through the minutes of a single committee meeting and you will realise why no one has ever managed to produce a readable account of the struggle for suffrage).

But the campaigners' engagement with visual representation was not confined to providing (sometimes staging) good photo opportunities for the proliferating newspaper industry. Rather, they exploited every angle, and used every medium to ensure that images referring to the rightness of women having the vote circulated as widely as possible in the culture at large. "Who takes the eye takes all," declared Mary Lowndes, a highly gifted stained-glass window designer and chairman (sic) of the Artists' Suffrage League. Postcards, teacups, badges, stickers, playing cards, posters, pennants, buckles and cartoons were all artefacts that could be easily inscribed with a campaigning message and then reproduced in bulk. It is these items, designed as ephemera but refusing to perish once their work was done, which form the basis of "Art for Votes' Sake", the first exhibition to focus on the visual arts produced in the suffrage movement.

There was a natural fit between this kind of commercial art-making and the political movement it was pressed to serve. The late 19th-century art schools, especially the Slade, had been good about letting in women, although they tended to steer them towards commercial rather than fine art (one of the banners shown in the exhibition wryly commemorates Mary Moser, one of two founding female artists of the Royal Academy in 1768 - it was 150 years before she had a successor). These deft and serious women, heads full of William Morris, wanted work that paid yet stayed true to the political and social underpinnings of their art. Designing images for use by the various suffrage organisations was a neat solution that suited everyone. Two organisations, the Artists' Suffrage League, and the Suffrage Atelier, set up in 1907 and 1909 respectively, were the main channels by which work from these individual artists, men as well as women, found its way into mass circulation.

The work of the Suffrage Atelier - which had an Arts and Crafts-style commitment to artisanal methods of production - is instantly recognisable and can be seen in some of the most effective pieces in the exhibition. Jessica Lloyd Walters's Asquith and suffragette prisoners, for instance, makes a virtue out of the SA's quick, cheap methods, which also nod towards developments in modern art, especially the newly fashionable "primitive" woodblocking and stencilling. In this particular poster, bold monochrome (colour was just too expensive) and a graphic approach creates a chilling effect, as disembodied female faces pile up like discarded skulls.

The ASL, by contrast, put out work that was more obviously the product of trained hands. One such, Convicts and Lunatics by Emily Harding Andrews, places an idealised image of a woman graduate against those of a convict and a lunatic. The text makes it clear that what connects these three is their inability to vote. Andrews's artistic execution may be deft, but her implicit argument is off-putting. There is something about the graduate's regular features compared with the puffy face of the lunatic and the sloping brow of the convict that suggests the educated woman's fitness to vote rests on nothing so much as her eugenic superiority.

In fact, whenever suffrage artists get drawn into making comparisons between women (usually upper-middle-class women) and other social categories, then tensions and ambiguities arise. Working-class men, all of whom had the vote by 1884, are most often portrayed within the visual field as shifty, drunk, violent or lazy. Working-class women, when they appear at all, are often shown as needing the vote in order to escape grinding poverty or spousal abuse. While these images do their work brilliantly in one context - why should a highly educated woman not have the same legal rights as an illiterate man; why should a hard-working seamstress not be able to vote when her layabout of a husband can? - the implications are disturbing. Sylvia Pankhurst, one of the movement's most talented artists, whose political interests embraced socialism as well as feminism, is noticeable by her refusal to put these stereotypes to work in the service of suffrage. Examples of her art in the exhibition include a pencil drawing of Women in a Pot Bank and the postcard "Workless and Hungry", both stringent in their intent to get the realities of working-class life down on paper.

One of the most pleasurable parts of the exhibition consists of a series of banners carried by various branches of the suffrage organisations on the big national marches (it comes as no surprise that the committee of the WSPU asked artists from the ASL to choreograph these processions for maximum visual impact). Mary Lowndes of the ASL was the guiding force here, briskly telling anxious amateurs that there was really nothing to it: if they could run up a pair of curtains for their dining room, they could certainly manage to produce a banner. Lowndes was on firm ground: not only did middle-class women still do most of the needlework within their own homes, but they were active in church sewing circles. For that reason, several of the exquisitely stitched banners borrow their designs from religious iconography. That produced by the Women's Freedom League in 1909 combines what looks like a sacred heart with the motto "Dare to be Free", the reassuring conservatism of the image going some way to muffle the unsettling implications of the slogan.

The exhibition ends with a section on the inconvenient fact that some suffragettes put as much energy into destroying art as others did creating it. From 1913, when three women were arrested for smashing the glass protecting 13 paintings in Manchester Art Gallery, suffragettes targeted artworks that seemed to suit their purpose. This meant going for either the most valuable pictures, or else those whose content seemed to comment on the current struggle for suffrage. In 1914, Dorothy Richardson attacked the Rokeby Venus with disturbing frenzy (the cuts were on the torso, which made it seem as though a body as well as a painting was being destroyed). Richardson's justification was clumsy if sincere: "I have tried to destroy the picture of the most beautiful woman in mythological history as a protest against the government for destroying Mrs Pankhurst who is the most beautiful character in modern history." Sometimes, though, the thinking was mystifying: Sargent's portrait of Henry James was hacked about in 1914. Not only was James a feminist, but the attack provoked him into a response so typically linguistically contorted that Mary Wood, the culprit, must have wished she'd left well alone.

"Art for Votes' Sake" is a thoughtfully curated exhibition. The majority of the artefacts come from the Women's Library (formally the Fawcett Library) and the Museum of London and are, in that sense, familiar. But what curator Bethan Stevens has done is arrange the pieces into a narrative that is both clear yet complex. A typically clever bit of staging involves an issue of the National Union of Women's Suffrage Societies' magazine, which is opened out to show both the front and back cover. The front image is a photograph of Mrs Fawcett, the union's president, who was suspicious of any appeal to the visual and was herself a stern and sturdy-looking lady. On the back cover of the magazine is an advertisement for Morny Bath Salts using artwork provided by the company that shows an erotic and fanciful nymph-like nude. It is within these contradictions, so nicely understood by the exhibition, that the story of art and suffrage lies.

"Art for Votes' Sake: visual culture and the women's suffrage campaign" is at the Women's Library, Old Castle Street, London E1 (020 7320 2222) until 20 December