Jack White improvised one of the songs on his new record on the spot.

The singer is about to release his first solo album, Blunderbuss, and was keen to challenge himself, so invited some musicians over and composed one of the tracks spontaneously.

"I had six sessions musicians invited to come in in the morning, and I had no song, I had no idea, nothing. And I went in the room and I pretended like I had a song. I sat down at the piano and played a C chord and then an F and thought, 'I gotta write something. Right now, right now!' These aren't friends of mine, they're studio session musicians waiting for me to tell them what to play. That forced me to do something I would never have done!" he told NPR.

Jack - who previously fronted The White Stripes - recorded the album with a number of different musicians, both session players and friends, including an all female band and an all male band, and was interested by how the dynamic of the recordings changed depending on the sex of the players.

"I learned with The Dead Weather that you just have to have one girl, it takes only one girl, even if you have twenty guys in the room, if you add one girl you change the entire mood and everyone plays differently," he added, referring to another of his bands.