Sewn Otabind, invented by Hexspoor, is a binding technique that produces optimal flatness. It is ideal for a book with a large number of spreads, because the pages remain flat when the book is open.
Hexspoor glues the cover to the first and last pages of the book block, but leaves a small space along the spine. This creates a gap, so that the book block “floats” away from the cover. This technique, when combined with a pliable cold-setting glue for the adhesive on the spine, produces very good flatness.
We also use hot-melt and cold-setting glue along the side to give extra strength to the book.