Kate Winslet explains how she came to projectile vomit on screen.

The actress, who plays investment broker Nancy Cowan in Roman Polanski's Carnage, revealed all in an interview with this month's EMPIRE Magazine.

"Ah, yes, the vomit scene," she smiles. "Now that really was an unforgettable day..."

Winslet plays one formidable half of a power couple (hubby Alan, played by Christoph Waltz, is a hotshot lawyer) whose son has been accused of bullying. The Cowans rock up at the 'victim's' apartment to discuss this unsavoury incident with his parents, a very earnest, passive-aggressive liberal, Penelope Longstreet (Jodie Foster), and her husband, regular guy Michael (John C. Reilly).

A polite, discussion about a playground brawl erupts into a 12-round verbal slugfest where each is trying to land a knockout on the others. The polite veneer of four outwardly well-to-do parents is stripped away to reveal a set of latent prejudices just waiting for the right moment to bubble up to the surface. After homemade pie and too much Scotch, Nancy starts to feel decidedly dodgy and, suffice to say, Winslet doesn't make it to the bathroom in time and vomits all over Penelope's precious coffee-table collection of art books.

"Actually, it was only the second time that I've had to throw up on screen, the first being a very small piece in episode two of Mildred Pierce," reflects Winslet. "But with this I had to contain a lot of vomit in my mouth, which is not possible. Without going into too much detail, it was a very complex rig and there was some extremely clever CGI involved."

She added: "My kids came to work for that day, the vomit day, and they literally haven't stopped talking about it since. On set, everything smelled of sick all day. I went home and it was between the cracks of my fingers, in my hair, just everywhere. When we shot that scene we were all absolutely beside ourselves with laughter."

For Winslet and the other three A-listers, the chance to work with Polanski was too good to resist. "When Roman Polanski invites you to be involved in a project, you don't say, 'No,'" she says. "And the script was extraordinary. I'd seen the play in New York so I was already very much a fan of the piece. I just felt very fortunate to be included."

"He's just brilliant," gushes Winslet. "He has such energy, he's incredibly professional and so focussed on every detail."

The January issue of EMPIRE Magazine is on sale now (Thursday). Carnage is out on February 3, 2012.