When Westerners come to Iran one of the first things they notice is the traditional tent-like chador worn by many Iranian women (chador is actually Persian for 'tent'). It's all Greek to outsiders like me, but to the seasoned observer, there's a world of difference between a chador with sleeves and one without, or when worn over jeans or stockings, all sending calibrated signals of different social values.

Mohaddeseh (above) is a 22-year-old student at a university in a town east of Tehran. All the women in her family wear the chador, but unlike them she wears brightly coloured clothes underneath, with scarlet trainers and lots of make up. They don't approve, but accept that times have changed. Most of the students at her university don't wear chador at all - they prefer a more revealing tunic (a manteau) and a colourful headscarf.

"At home they tell me you should wear plain clothes under a chador, but I like wearing these," she says. "Only one friend at university wears a chador. Things change so fast that in 15 years you probably won't even have to wear a manteau, let alone a chador."

An elderly woman, a retired schoolteacher, stops in the bazaar to say she has always worn the chador - even when travelling to Western countries or the Far East. "I have worn this since I was 10 years old," he says. She wears black stockings underneath, suggesting she is quite traditional. "But my daughters live abroad and don't wear it in daily life. I don't like the way young women wear make up with chadors. That's for parties. With a chador it's better to look natural."

My translator says her uncle always used to say that a woman's face in a black chador "stands out like a radish".

At Tehran bazaar the chador salesmen are found along a narrow alleyway between the leather jackets and the cloth sellers. They have rolls of lightweight black material, each subtely different in shade and pattern. Tradional women buy a length - usually five-six metres for a chador - and make it up themselves at home. In the past, light coloured, floral chadors were more common, but since the revolution, funerary black has become more popular.

"In the past, new fashions only came every couple of years," says Hamid, a Gilani salesman in the bazaar. "Now it's every month. Older women still make them up at home but trendier women like the ready-made ones with sleeves. Sequined chadors are popular too."

His most expensive is a silky jet black cloth with a dark pattern of blades of grass and delicate flowers. A chador of this quality would set you back $100 - and it's worn to sofrehs, women's social events ostensibly given for a charitable or religious purpose. A stall further along sells more white and floral material - preferred for prayers when women should not wear black.

In a modern mall just off the bazaar a shopkeeper sells more fashionable models - the kind girls like Mohaddeseh might wear. Quite often these are worn because it's required by a particular job or university, with more modern, colourful clothes underneath. In the modern shop, the chadors with sleeves, zips or slits for the hands are most popular - and least traditional.

Mohaddeseh tells a story that seems to reflect the split between traditional and modern chadoris rather well - "A boy came up to me in the street the other day and said: 'you're very pretty... shame about the chador'". She giggles, well pleased that he liked her. The older woman in the bazaar would have been scandalised. For her, the chador is supposed to deflect exactly that kind of attention.