Bob Rock worked with Metallica on The Black Album after producing Mötley Crüe's Dr. Feelgood.
Metallica admired Rock's work on Dr. Feelgood, Mötley Crüe's 1989 studio album, and chose him to produce their own follow-up to …And Justice for All. Rock's reputation for creating a strong, polished rock sound made him a logical choice for a band seeking a new recording approach.
The partnership was not immediately comfortable. Rock challenged the band to improve arrangements, lyrics, and performances, while Metallica members were accustomed to working with a high level of control. The sessions involved frequent arguments and numerous takes.
Rock's influence was especially audible in the fuller production. He encouraged live group performances, harmonic vocals, and a more prominent bass presence. Those decisions helped the album sound less intricate than earlier Metallica records while retaining considerable weight. The collaboration became one of the most important producer-band partnerships in the group's career.