A perfect-bound book is a block of pages glued into a cover. It opens to about 180 degrees, and past that the spine starts to fight back. A wire-o or spiral book opens through 360 degrees, folds back on itself and sits flat on a table. The trade is that the binding stays visible: a row of punched holes and a metal or plastic element running through them. For a workbook, a manual, a swatch set or a cookbook that has to stay open while both hands are busy, that trade is usually worth taking.
Two machines, one preparation step
Wire-o, also called twin loop, uses a continuous length of formed wire. The wire is fed through the punched holes from the back of the block and the loops are closed at a closing station. The finished spine is rigid; the pages stay in line with each other and the book holds its shape.
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