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Bookbinding by hand, though largely replaced by industrial methods, remains practised for restoration work and limited-edition printing. The process begins with folding printed sheets into sections called signatures, which are then sewn together along the spine, traditionally using linen thread passed through raised cords for added strength. Unlike mass-produced books, which are typically glued rather than sewn, hand-bound volumes can be opened flat without straining the spine, a feature valued by libraries handling fragile historical documents. After sewing, the spine is often reinforced with glue and a strip of fabric before boards are attached to form the cover. Because each stage depends on the previous one being executed precisely, a single misaligned signature can compromise the durability of the entire volume, which is why apprenticeships in traditional bookbinding often last several years before a binder works independently on valuable manuscripts.