I’ve just been posing with no clothes on, painted blue. All in the name of art

The moment Spencer Tunick said: "So, take your clothes off and leave them here," it hit me that stripping off for art might not be such a great idea.

At the weekend I went along to the Big Chill festival in Herefordshire and signed up to take part in American artist Spencer Tunick's latest nude installation. It was 7.30am and over the next three hours we were to be totally naked but for some blue, light blue, pink, black or yellow body paint, assuming various poses for Tunick's photographs.

As the 700 people around me began to peel away their garments and discard the layers of their modesty on the grassy hillside, I sat still for a few seconds thinking: "Here? Now? I'm not sure I can do this." I felt nauseous.

But naked girls were already skipping down the slope — apparently elated to be rid of their clothes. It was too late to back out now. So off came my dress, my bikini top, my underwear, and I, along with my boyfriend, joined the fleshy mass heading to fetch body paints.

Somewhere in the crowd were two friends — another couple. We had agreed to separate early on (it's one thing revealing your body to strangers, it's quite another displaying yourself to people you have to see every week) and, knowing them well enough to be sure they would plump for yellow paint, my boyfriend and I made a beeline for the pots of light blue. We had wanted no chance of bumping into their bits and, as we swept the blue stuff all over our bodies (total coverage necessary), it was quite clear that everyone in our colour group was going to get an eyeful of ours. (You try spreading paint on your toes without bending down and revealing a little more than you'd hoped — it's not so easy.)

Yet soon all embarrassment had vanished. By the time I was Smurf-coloured from head to toe I was happily standing face-to-face with a stranger helping to fill in the missed patches on her cheeks — nakedness all but forgotten.

After that, the rest was easy. Tunick barked his instructions through a megaphone and the crowd obeyed, baffled by his vague commands ("You, the tall man in dark blue. Take a step forward"), giggling when the camera appeared to get the better of him ("Have I got the right setting?"), and intermittently starting up colourful songs ("I can sing a rainbow "). Even having to lie down on the ground, the back of my head resting in the dark blue crotch of a strange man, another unfamiliar head (colour unknown) resting on my stomach, was amusing rather than scary — if a little disconcerting. The sun was shining and everyone was enjoying themselves, cheering and clapping each other along.

In the end, the oddest moment of all was putting our clothes back on. While yellow, blue, black and pink paint had looked spectacular on nude bodies, with clothes people suddenly resembled The Simpsons, or Tony Harrison from The Mighty Boosh.

One man reflected that he would be quite happy to stay naked and body-painted all day — and I almost agreed. Taking off my clothes had made me feel much happier with my body, although not, as he said, "because everyone is a different shape and everybody is beautiful", but more because I realised that everyone is just as imperfect as I am.

We headed back towards our campsite where the remaining Big Chillers were keen to find out why we were painted blue. They seemed just as fond of our new colouring as we were. Others, though, were not so lucky.

"Maybe it would have been OK if we were painted a different colour," we heard mumbled from behind us. We turned around to see a couple who had been painted in black.

"Everybody has been shouting abuse at us, calling us racist," they explained. How strange, we thought, that people are treated so differently depending on the colour of their paint.