These sheets were combined manually on a light table, in a process called stripping. When pages were set using movable type, pages were assembled in a metal frame called a chase, and locked into place using wedges called quoins.īy the late twentieth century, most typesetting was onto photographic film. Imposition has been a requirement since the earliest days of printing.
The example below shows the final result prior to binding and trimming. A third fold completes this process (page nine meets page eight). Then it is folded again horizontally (page four meets page five). After printing, the paper is folded in half vertically (page two falls against page three). There are eight pages on the front of the sheet, and the corresponding eight pages on the back. In the example above, a 16-page book is prepared for printing. A little copy is then created, and this can help paginate the product. This is made by folding several sheets of paper in the way the press will print and fold the product. To understand how the pages are related to each other, an imposition dummy may be used. These fibers must run lengthwise along the fold, which influences the alignment, hence the position, of the pages on the printed sheet.
To achieve this, the printed sheet must be filled as fully as possible. It consists in the arrangement of the printed product’s pages on the printer’s sheet, in order to obtain faster printing, simplified binding and reduced paper waste.Ĭorrect imposition minimizes printing time by maximizing the number of pages per impression, reducing cost of press time and materials. Imposition is one of the fundamental steps in the prepress printing process. For the historical British taxes, see Impositions.
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