Theory and practice of bookbinding / United States Government Printing Office.

  • United States. Government Printing Office.
Date:
1962
Catalogue details

Licence: Public Domain Mark

Credit: Theory and practice of bookbinding / United States Government Printing Office. Source: Wellcome Collection.

    250/260 (page 238)
    simple operations of jogging, piling, and counting are performed more frequently than others, but they are very important because dif- ficulties will be encountered subsequently if they are done carelessly or in a slipshod manner. Skill can be attained only through practice with the different grades of paper. The printed sheets as they are delivered to the bindery usually have several pages on each side. The arrangement of the pages in the form is known as imposition. When the form is imposed correctly, the pages will be in their proper sequence after the sheet is folded. The folded sheet is known as a signature, and in general trade practice it consists of 4, 8, 16, or other combinations of pages. Factors to be con- sidered in the imposition of a signature are the kind of paper on which it is to be printed, the sewing-swell tolerance, the grain of the paper, and the most efficient folding or sewing method. The principal folds are the right angle, which is most commonly used for bookwork; the parallel, for long narrow pages or for those printed two up; and the accordion, for maps and folders, as well as some book signatures. Folding machines employ either the knife or the buckle principle, in both of which the fold is produced by passing the paper between rollers. Different models will fold different sizes of paper. The Government Printing Office has two makes of folders which handle sheets in sizes up to 42 by 56 inches, and another which can fold sheets as large as 39 by 64 inches. One company lists 152 different standard impositions that can be folded by their machines. Some folding machines will perforate, slit, score, insert, paste, or stitch. Automatic feeders of three kinds, pile feeders, continuous feeders, and friction feeders, speed production. One model of folding machine is con- structed especially to handle large sheets of ruled paper for blank books. After signatures have been folded, the next steps are bundling, gathering, and collating. The purpose of bundling is to protect the signatures, keep them from becoming mixed, make them more com- pact and easier to stack and handle, and prevent them from being bent or curled. Bundling is done in signature or bundling presses, either by hand press, power press, or pneumatic press. The signatures are assembled by the process of gathering by hand or by machine. Then they are collated, which means that they are examined to ascertain whether they are correctly gathered and in proper sequence. The end papers are pasted to the first and last signatures. End papers may be defined as a unit of two or more leaves placed in the front and the back of a book between the cover and the text. The leaf nearest the first and last signatures, respectively, is tipped on, and inserts, such as illustrations, maps, plates, etc., also are tipped in at this time. |