Page 161 - Graphic Design and Print Production Fundamentals

Graphic Design 149
same sheet, whereas a perfect-bound book has the first pages imaged on the same sheet, and last pages
on separate sheets of media.

There are many options for folding a sheet of substrate before binding it together. The options increase
the larger a sheet is. An imposition must account for the preferences that are best practices for the
specific machines involved. If we look at sheet-fed lithography first, we can identify some common best
practices that can also apply to toner-based electrophotography and inkjet. We shall leave an examination
of imposition for flexography to discuss nested dieline shapes for packaging applications.

Imposition standards are based on workflows for standard-sized pages, primarily letter-sized pages
measuring 8½” x 11″. We speak of two up devices that can generally image substrates up to a maximum
size of 12″ x 18″ or 13″ x 19.” Two up devices can accommodate two letter-sized pages plus bleeds,
grip, marks, and colour bars — sometimes referred to as furniture on an imposed sheet. These four
elements all serve a purpose in page reproduction manufacturing that we shall define later. Four up
devices generally accommodate imaging substrates up to 20″ x 29″ to image four letter-sized pages.
Forty-inch devices are referred to as eight up and image on a maximum sheet size of 30″ x 40″, which
can image eight letter-sized pages and the furniture mentioned above.

There are four common styles of imposition for eight up devices: sheet-wise, work and turn, work and
tumble, and cut and stack.

Figure 5.1 work and turn(a)