Job Backer

Books being created or repaired by hand usually need backing and rounding. The job backer is the heavy iron press used to secure the text block for these processes. A newly stitched text block will be thicker at the spine edge than at the fore edge, and the thread-swollen spine has to be molded so that the thickness is evenly distributed across the spine. 

The practitioner uses a hammer and glancing blows to accomplish the task, creating a mushroom-like profile. The boards of a book cover easily nestle into the shoulder (the overhang of the mushroom cap), giving the book its joints.