The actress recently added some length for her role in "The Bitter Pill"

By Kate Hogan
Updated April 17, 2012 10:00 PM

Splash News Online

Talk about playing extremes: after chopping, dying and shaving her hair for her role in The Girl with the Dragon Tattoo, Rooney Mara recently lightened her locks and added lengthy extensions for her latest film,
The Bitter Pill
. But thankfully the transformation wasn’t quite as traumatic this time around, according to her hair stylist.

“Rooney was excited that she was unrecognizable — even her driver didn’t recognize her on the way out of the salon,” stylist Kristina Barricelli, co-owner of New York’s Gemini 14 salon, tells PEOPLE. “She was really excited because she’d never tried extensions.”

Barricelli used Great Lengths Extensions on the star, after the film’s crew decided that strand-by-strand extensions would be more believable than a wig. First, Barricelli’s sister dyed Mara’s hair — “She made it possible to take her from jet black to ombré without ever compromising the condition of Rooney’s hair,” she explains — then experts at a color lab in Italy hand dip-dyed the extensions to match.

“She needed to look like a disheveled woman that is battling deep depression for her role,” Barricelli explains. “We decided ombré would give her the opportunity to look chic on the red carpet but still look unkempt for the movie. It was a perfect solution for her.”

Though there were a few challenges — Mara’s hair is still quite short on the sides because of Dragon Tattoo — the team made the look work, and the star couldn’t be happier. In fact, she’s already given the do a red-carpet test run.

“Rooney will have the extensions in until she’s done shooting,” Barricelli explains. “So it’ll be fun to see her play with her new hair.” Tell us: What do you think of Mara’s new look?