Saddle Stitching

Saddle Stitching is the process of folding several sheets in half and stapling them at the spine to form a multi-paged publication. We have two 6-pocket, three-knife saddle stitchers to handle saddle-stitching up to 72 pages. For larger publications, perfect binding, in which the signatures are glued at the spine and wrapped with a cover, is required.

The saddle stitcher is actually quite an amazing machine. The signatures, large sheets folded three times to create 16 pages, are loaded in respective stacks along the units of the stitcher. A conveyor carries the signatures along as they are collated and then are stapled. The stapled signatures are then trimmed by the three knife trimmer and the finished product is counted and delivered.

Design Considerations

Signature Pagination	In any saddle stitched publication, the total number of pages must be divisible by four due to the nature of folding paper. Depending on how the project will be printed, a 12 page publication may be almost as costly as a 16 page because of the added trimming involved in assembling dissimilar signatures. For example, an 8.5" X 11," 16 page program will print entirely on 23" X 35" stock. The sheet is folded three times and trimmed on three sides to make the booklet. With a twelve-page publication, the signature cannot be folded into "thirds" for binding. Since the folds must all be on the same side it must be printed as two pieces -- an eight-page sig and a four-page sig. There are several methods of economizing the paper use for this publication, but there are added cuts and steps in bindery that add to the cost of such a project.
Crossovers	A crossover is wherever an image or design element spans two or more pages that are not actually printed side-by-side or even on the same sheet.
Creep	Creep is the result of folding several sheets of paper together, causing the printed image to "move" away from it's target position. Creep is an issue on any publication that folds, especially saddle-stitched publications. The thickness of the spine can be 3/16" to 1/4". The pages in the center of this publication get pushed farther and farther toward from the spine and can get dangerously close to the trim edge. To be safe, try to work with a 1/2" margin on all saddle stitched publications over 16 pages.
Bleeds	A bleed is wherever an image or design element is supposed to continue to the edge of a page. As accurate as equipment is, uncontrollable factors, such as paper stretch due to changes in humidity and the pressures exerted on paper in the process of printing on it, can cause the paper to stretch or shrink. If the image "stops" right on the edge of where it is supposed to trim, it is very likely that you will see a white line down the edges of some of your pieces. To prevent this, always let the image extend at least 1/8" beyond where you intend it to trim.