Just the ticket! Painter finds his perfect 'canvas' on Paris Métro

You've heard of underground writers, but Luc Grateau's work gives the term underground artist a new meaning. Every day for three years, the artist has used old Métro tickets to create miniature portraits of fellow passengers in Paris.

Since he began the project in the autumn of 2004, Grateau, 47, a manager at a French government research organisation, has painted more than 1,000 portraits. Only once has someone got annoyed and asked him to stop. More often people are just curious.

"Every day in Paris, you see dozens of different faces but by the evening, you can't remember any of them," he said. "For me, it is important to try and remember."

Grateau paints to record all those tiny moments, a look, a smile, that thousands of people fleetingly exchange every day while travelling on the Métro. "Frequently I am so absorbed in what I am doing I forget to get off," he said.

Each day, often during his daily commute to work on the Left Bank section of lines 10 and 12 in the south of the city, Grateau captures a new expression, a new moment in the hustle and bustle of the underground world.

Every portrait is done against the constraints of time, format and movement. And when he gets on the Métro what captures his attention? "I don't necessarily pick the person directly opposite me," he says. "I go for something which poses a challenge for me – a hat, a scarf, a particular colour or texture." And at the end of the day the new portrait" gets added to the archive he has created on his website, www.serialpaintings.net.

He does the portraits discreetly and quietly, not wishing to disturb or annoy. In compliance with the metro's "rules of discretion" there are no obvious signs of paintbrush and canvas. His secret against the swaying of the trains and the jostling of passengers is a hand-sized paintbox. And secured into this rectangular box are his mini-canvases, Métro tickets measuring one-and-a-half inches by three quarters of an inch, along with his paintbrushes and palette. The palette is a former lip-gloss tray which he has innovatively converted by replacing all the lip glosses with dabs of oil paint.

Grateau's underground activities are not however only limited to his ticket paintings. He has also taken it upon himself several times to repair damaged posters lining the passageways of the metro system. He does the restoration on the spot by filling in with oil paint the parts that have been torn away. Once finished, he photographs the result, which is often not too dissimilar. But unlike his "ticket portraits", which he preserves, these "restorations" are short-lived and are soon covered by new posters.

He says he does not have any particular projects in mind for the future: he wants to continue with his portraits, each day capturing something new and different.