Getting naked with 500 strangers is a great leveller.

We'd all been sitting together, fully clothed, for more than an hour in a warm, cavernous room in Prahran on a Sunday afternoon.

Many chatted and laughed. But some — not knowing another soul in the room — sat quietly, making furtive eye contact with others.

We were the lucky 500 who'd been chosen for the first of two Melbourne installations by renowned mass-nude photographer Spencer Tunick. More than 10,000 people had applied.

While we sat on the floor awaiting instructions and pondering the small white tubs of body paint that had been handed to us on the way in, the suspense became too much for some.

Test patches of dotted colour became whole faces smeared in red or yellow.

Trouser legs were pulled up so calves could be rubbed with a vivid blue.

Premature, yes, but it just stoked the excitement.

Lying on the cold concrete, we all hoped to glean some warmth from our neighbours. ( Supplied: Spencer Tunick )

A private moment and a prayer

For a brief moment, an American assistant with lanyards and a megaphone kept the crowd entertained.

We're waiting for the right light, we were told. Don't take your clothes off yet. But if you need a nervous wee, now is the time.

Finally, the man himself appeared at the doorway to cheers and applause.

Tunick instructed two men to stop filming him and put their phones away — this was a private moment.

He told us he'd done everything he could to keep us safe and to respect our privacy.

He invited us to think about everything that was happening in the world at that moment and offered up a prayer of hope to those 12 little boys huddled in a cave in Thailand. Murmurs of agreement and a ripple of applause went through the room.

A woman behind me muttered, not quietly: "Jeez, what is it with yanks and religion?"

It wasn't all body paint. Some participants were covered in pink veils instead. ( Supplied: Spencer Tunick )

The communal reveal

Then, it was time. Right where we were standing. A communal peeling off of layers.

Any nervous tension in the room evaporated once clothes were hurriedly removed and shoved into pink plastic bags.

Every inch of skin was slathered in thick body paint the colours of a rainbow.

Some participants stood tall and proud, others were slower to unfurl. But we all got there.

All just flesh and bumps and hair and wide smiles. Together.

Nothing quite breaks the ice like leaning over to rub body paint into your feet and inadvertently leaving a green print on a yellow person's left buttock behind you.

"I'm so sorry," I say, turning to look Mr Yellow square in the eyes. "I've put green on your bum."

Hot pink people helped other pinks fill in the spots they'd missed. Orange folk rubbed paint into their fellow oranges' backs like sunscreen.

Then it was out into a typically bracing Melbourne winter's day. A glorious crowd of painted beauty practically skipping to a parking lot off Artists Lane.

Tunick was high up on a cherry picker, waving at the delighted rainbow throng below.

For an hour, he instructed us to stand, crouch, put one arm up, walk about, not smile.

We lay amongst each other on cold concrete, purple shoulders flush up against green thighs, hoping to glean some warmth from our neighbours and silently looking up at the clouds crossing that wintry sky.

Just the sound of Tunick's camera shutter, occasional instructions and the odd wry aside and giggle.

Veiled and painted from head to toe, these participants turned a rooftop car park into a sea of red. ( Supplied: Spencer Tunick )

Staring down the interlopers

For the next set-up, we were shepherded into a damp and cold adjoining laneway.

As we filed past a floor-to-ceiling window at the back of a cafe, patrons behind the glass produced mobile phones and started filming.

This was going straight to Instagram. Boos and cries of "not cool" issued from the naked group in the laneway.

We were suddenly vulnerable and exposed in the presence of those clothed and warm non-participants.

But a calm acceptance quickly came over the crowd.

A beautiful Rubenesque woman painted purple stood squarely in front of the window, staring the interlopers down.

She didn't care. And then neither did we. In that moment, we were all connected.

After our final shots, we filed out of the laneway and back into the lot, with waves and warm thank yous from Tunick.

As we left, we all turned together and marvelled at a full rainbow stretching across the sky above South Yarra. It would have been an incredible photograph.

But the only cameras that could have documented it were Tunick's.

For the rest of us, it was mental snapshots only.

The author of this story has chosen to remain anonymous.

Tunick's photo shoots around the world

Tunick has previously photographed over 5,000 nude Sydneysiders on the steps of the Sydney Opera House in 2010. ( AAP: Dean Lewins )

In 2016, Tunick's 'Sea of Hull' project was shot in northern England. ( Reuters: Andrew Yates )

Tunick also photographed volunteers at San Sebastian's Zurriola beach in Spain in 2006. ( Reuters: Pablo Sanchez )

Around 2,000 naked volunteers posed in the Europarking building in Amsterdam in 2007. ( Reuters: Koen van Weel )

In Germany, Tunick directed models to pose in front of old paintings at Dusseldorf's Museum Kunstpalast in 2006. ( Reuters: Ina Fassbender )

The Kursaal auditorium in the Spanish city of San Sebastian featured in another of Tunick's photos in 2006. ( Reuters: Pablo Sanchez )