What is Signature?

A finished book may appear as if it is made from a stack of loose pages. In many cases,multiple pages are often printed together on a much larger sheet, then folded, collated and trimmed on all sides. The trim eliminates the folds and leaves smooth edges. This is called creating signatures for binding.

A signature is a sheet of printed pages which, when folded, fall in order and become part of a book. Books may be made from more than one signature. Before a signature is created, prepress, in cooperation with bindery, must decide how to lay out the press sheet so the pages will appear in the proper sequence after the press sheets are folded and bound. This is called an imposition.

Flat sheet showing page imposition

Flat Sheet Showing Page ImpositionThis flat sheet will result in a 16-page book[eight pages on the visible side and eight pages on the back]. Booklets and brochures of 8, 12, 16 or 32 pages may be made from a single folded press sheet depending on the size of the finished piece and the size of the paper. Imposition is the arrangement of pages on the sheet. Proper imposition guarantees that the pages will appear in the proper sequence and position after the sheet is folded and/or trimmed and bound.

What Is Signature

When a press sheet is folded down, the inside pages will push out further from the spine than the outer pages. This is called creep or push out. The margins of these center pages must be adjusted so they compensate for creep, ensuring that the final pages have consistent margins. The heavier the stock, and the more pages in the signature,the more creep or push out will exist.

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