Slash spent more time dealing with bureaucracy than recording for his new album.
The former Guns 'N' Roses guitarist assembled an all-star cast for his first solo effort, 'Slash', but says although it meant a lot of hassle from record companies, it was worth it because he got to play with his heroes.
He said: "It took four months to make the record. I had to write all the material then I had to make demos to send to all singers.
"Then the thing that made it take the longest was getting releases from all the different artists' record companies."
He added: "Sitting next to Ozzy while he's writing lyrics and practicing the vocal is really a f***ing trip. I've been listening to Ozzy since I was like 13 years old."
Slash added to Rolling Stone magazine: "I think people are gonna trip when they hear the stuff Fergie is capable of.
"I really wanted to do something with her so people could hear what her rock chops are like."