In binding and finishing, a means of binding pages together involving the sewing of printed signatures together with thread followed by encasing the signatures between cloth-covered cardboard covers. Case binding is used for hardcover—or casebound—books, and comes in three different types: edition binding is the use of fully-automated equipment to bind relatively large print runs; job binding is the binding of small quantities of books which require special bindings, often including some degree of hand-work, such as leather-bound Bibles; library binding, like job binding, is used for small quantities and usually involves some degree of hand-work. Library binding is used to create specially-reinforced bindings for library usage, and library binding services also repair and rebind damaged books.
There are three basic stages to the case binding process:
'Thread Sewing'. The first step in the case binding process is thread sewing, in which printed signatures are stitched together by means of a needle and thread. There are two types of thread sewing: side sewing passes the thread from signature to signature through the side of the book, the stitches running parallel to the binding edge. In side sewing, the binding is strong, but books do not lie flat when opened. Side sewing is most often used for library binding and repair work. It can be performed by hand or by special sewing machines (much like home sewing machines) which run the thread through drilled holes. Saddle sewing, also called Smyth sewing, passes the thread through the signature fold at the spine of the book. Since books which are saddle sewn tend to lie flat when opened, it is the more popular form of thread sewing.
After gathering of printed signatures, each signature is fed to an infeed saddle and conveyed to a sewing saddle. A complete book block is then automatically stitched. The type of stitch used depends upon the thickness of the book. In both the standard sewing pattern and continuous lockstitch, the stitch is placed in the same position on each signature. This results in thread build-up, or an increase in book thickness caused by the alignment of the thread stitches. On thin books, thread buildup can be compensated for by compressing the book block after sewing, or, on thicker books, by using a staggered sewing pattern in which the position of the stitch is offset slightly from signature to signature. A fourth variety of sewing pattern is a continuous staggered pattern, which maintains an even spine thickness, but uses more thread. The continuous staggered pattern produces the most secure bindings.
After thread sewing, book blocks are conveyed to a three-knife trimmer for reduction of the pages to the desired trim size.
'Forwarding'. After trimming, there are several operations, some necessary and some strictly decorative and therefore optional, known collectively as forwarding. The first steps—rounding and backing—are needed to shape the spine of the book so as to more effectively fit the cover. In rounding, the book block is clamped into position between two counter-rotating rollers which impart a convex shape to the spine. In backing, the book block is clamped between steel plates and the binding edges of the sewn signatures are bent outward over the clamped edges. This results in a spine that is wider than the rest of the book, and provides shoulders for the front and back covers to rest on. It also creates hinge creases allowing the book to be opened.
A variety of structural or decorative enhancements may also be made at this point, depending upon the nature of and the production budget allotted for the book. Gluing-off involves the application of an adhesive to the spine as a means of reinforcing the thread sewing and to maintain a convex shape. Edge treatments involve such things as edge staining, the application of a dye or other colorant to the top, bottom, and/or side edge of the book block, or gilding, a similar application of gold leaf. The addition of headbands—decorative strips of cotton or silk attached to the top and bottom of the spine—and/or book marks—ribbons or cords which function as decorative placeholders—may also be done at this time. Special and deluxe editions tend to have more of these amenities than do regular editions
'Casing In'. The attachment of a cloth-covered cardboard case is known as casing in. Book cases are manufactured for a particular book just prior to casing in. Strips of board are cut and trimmed to size and fed into a casemaking machine, which fits the cloth backlining over the boards, folding the excess cloth under the boards and gluing it securely in place. Covers may either be preprinted or, after casemaking, may be embossed with the title, author, publisher, and any other text or design.
Prior to casing in, the process of nipping—or an application of pressure to the spine of a book block—is performed to compress the threads (reducing the effect of thread build-up) and force out excess air. Alternately, smashing applies pressure to the entire front and back of the book block, rather than just the spine.
During casing in, the end papers of the bound book block are coated with adhesive, and the cloth case fitted over the pages in such as a way as to ensure that the front and back covers project evenly over the edges of the pages. After casing in, the process of building-in uses pressure and heat to dry the adhesive and to cause the cloth to conform to the rounded and backed spine. In trade book production, after building-in the books can undergo jacketing, or the addition of a printed paper dust jacket.
(See Binding and Finishing.)