Suspended between two trees along the Seine River in Paris, a graffiti mural flexes slightly in the breeze.

It's painted on plastic wrap - up close you can see little folds in the overlapping layers - wrapped around the trunks and pulled taut to create a new "wall" in front of the stone behind it. It's called CelloGraff.

Paris is known for its art, but usually evokes visions of grand museums, and masterpieces by artists like Leonardo Da Vinci or Pablo Picasso.

Leaning against the bar in a Parisian cafe, wearing jeans and a beat up jacket, Astro says brushes don't interest him.

But give him a few cans of spray paint and a roll of plastic wrap and his work explodes with colour, and is more detailed than seems possible with a spray can.

Astro Greg has been tagging since he was 18, starting out like most graffiti artists, as a vandal. He and CelloGraff co-creator Alex Kanos have known each other for ten years.

Kanos's story is similar. He did his first tag, "Chikanos", in high school, but what he considers his first real piece, the letters KNS and a manga-inspired character, at 20. "It was horribly awkward, like all first pieces," he admits.

Museums like The Louvre might as well have been in another country for all the influence they had on Kanos, growing up on the northern outskirts of the city.

"In the suburbs the only artists that we really had access to were graffiti artists," he said, adding that was in awe of the work he saw on the street.

"It was the kind of thing where I thought, ‘if I had the tools, I'd copy that right away'," he said.

Kanos graduated from Paris's prestigious Ecole Nationale Superieure des Beaux-Arts (National School of Fine Art), where he first started experimenting with plastic wrap as a medium.

A few years later, in 2009, he returned to the material and, with Astro, started using it to construct walls for graffiti murals, often using trees as posts, stretching the plastic between them. Then they paint the new wall like any other.

Astro and Kanos realised they could build walls wherever they wanted, and take their time without having to worry about the police, because they were no longer doing anything illegal.

"We had decided that we wanted to do more elaborate pieces while a lot of our friends stayed on the vandal route," said Kanos.

-- Cutting out the clean-up costs --

They wanted to continue working in public places.

In France defacing a building can cost the tagger 1,500 euros ($1,960) in fines for a mild offence, or reach extremes of 30,000 euros ($39,000) and two years in prison.

Graffiti removal costs Paris more than four million euros ($5m) a year with three different companies employed to clean more than 200,000 square metres (2.15 million square feet) of walls annually.

That's what happens in a city that Astro says is saturated with taggers.

Since emerging in the 1980s, modern graffiti has flourished, and developed a wide range of styles. Astro describes his work as wild style, featuring tight designs, angular, abstract letters, and bright colours. It's not easy to read what his pieces say, but that's part of the point.

"If you've been doing graffiti your whole life simple letters are boring, that's one thing," Astro said

"But whether you use complicated letters or not it's about having a personal style."

With Astro nodding in agreement, Kanos adds: "It's a more of a message between taggers; it's not for everyone.

"We're trying to push the boundaries between forming letters and abstraction. If you feel something but don't understand (the words), that's perfect."

Cellophane offers different opportunities to push those boundaries. The walls can be shaped by the artist, bent around corners to create different forms.

Clear cellophane allows whatever is behind the piece to show through, and potentially become an element of the design.

For sanitation workers clean up consists merely of cutting down the plastic and throwing it away.

Around Europe other graffiti artists have got in on the action.

In a piece by Hungarian artist Fat Heat, a vulture perches on a branch in mid air, and is visible from both front and back.

The Swiss group Desstres enclosed the rectangular base of a canopy in cellophane, giving them four walls to work with.

Astro and Kanos are now sponsored by a spray paint company, and invited to demonstrate CelloGraff at festivals in Europe and North America.

They have won awards for their work from Artaq, an organisation that promotes urban art and is hosting a festival in Paris November 20-27 where the duo will showcase their work.