When you've signed on to play Sweeney Todd, the Demon Barber of Fleet Street, chances are good you'll be wielding razor blades every now and then. And when you've played Edward Scissorhands, one would expect you'd be comfortable with that sort of thing. But in an interview with the Glasgow Daily Record, Johnny Depp admits to having some trepidation when it came to lathering up his co-star in the film version of Sweeney Todd, Alan Rickman.

"The shaving cream made me really nervous," he told the Record's Brian Mciver. "It was the most uncomfortable moment of my life ...  [W]hen you get into the chair with a stranger and they lather your face up with sharp instruments around your throat ... it's frightening."

As scary as that may have been, there was that small factor of the Sweeney role being largely sung, and Johnny's never having done any public singing—even of the everyday variety. "I've never tried karaoke," he admits. "It scares the hell out of me. I've never been that drunk—and I've been drunk."

That the film was being directed by Johnny's longtime friend and collaborator Tim Burton (director of the aforementioned Edward Scissorhands) helped put the actor at ease. Even so, going into production, neither was sure if it would work. So Johnny recorded a demo tape in a friend's studio and sent a copy to Tim.

"I did that and sent it to Tim and he said we're going to be OK," Depp reports to Mciver. "And then I became a bit more confident."

Once the confidence was there, there came the character. Not surprisingly, for a film full of bloody murder, Depp looked to early horror film stars like Lon Chaney and Boris Karloff. But for the singing? A more surprising source of inspiration, perhaps: "Iggy Pop maybe. Iggy has a beautiful, deep quality, and he's a real crooner."

For more revealing insights from the Sweeney star, about the role and about his own worldview—"Most people are really nuts, and that's fascinating."—visit dailyrecord.co.uk. Nonesuch releases the complete film soundtrack December 18.