If you knew you were making a classic, you would probably want to spend as much time on it as possible to make sure it sounds exactly the way you want it. That wasn’t the case for Sabbath, though, as the band knocked out the entire album recording session in just 12 hours with producer Rodger Bain at Regent Sound Studio. The band played live in the studio with the tapes rolling, which captured the cold, inimitable feel of the burgeoning sounds of heavy metal.
The reasoning behind rushing to track the album in this tight of a window was twofold. The band only had two days booked in the studio and one of them was reserved for mixing, which took place without their presence. The members of Sabbath left for Switzerland after recording.