Binding and finishing
those activities performed on printed material after printing. Binding involves the fastening of individual sheets together, while finishing involves additional decorative actions, such as die-stamping, embossing, etc.
Although binding is a post-press function, binding considerations need to be dealt with in the prepress phase of any print job. There are many different ways to bind press sheets (see below), and certain bind margin allowances need to be made, which vary by binding type. The correct imposition needs to be determined at this time, as well. Imposition issues are usually the purview of the stripper, or the person responsible for the assembly of all the page elements. (See Imposition and Stripping.) A variety of layouts or dummies assist in the proper determination of correct imposition. A mechanical layout, provided by the designer, shows how all the disparate page elements need to be arranged. The stripper then prepares an imposition layout which illustrates how the page elements and whole pages need to be assembled in order to meet the printing, folding, and binding requirements. The imposition layout thus indicates page sequence, margins, trim marks, fold lines, press gripper margins, register marks, etc. A folding dummy is an actual-size press sheet which has been folded into pages of the desired size and marked with page numbers to indicate the proper page imposition. The folding dummy also indicates where the gripper margin is, an allowance for which needs to be made. A binding dummy is essentially a folding dummy that has been trimmed and bound in the desired fashion, to indicate how much margin is lost during binding. Some jobs—especially those that are to be saddle-stitched—may need shingling performed during stripping, so as to compensate for creep, the decreasing size of the binding margin caused by increasing page count.
When thinking about binding considerations prior to printing, the various characteristics of the paper need to be accounted for. For example, the basis weight and folding endurance of a paper will affect how many times a sheet can be folded. Very lightweight paper (such as Bible paper) may need special equipment in order to fold and bind the sheets without damaging them. The paper's grain direction also affects the ease with which finishing operations can be performed.
Cutting and Trimming
Cutting of paper stock may be performed at any point in the printing and/or binding processes. Blank stock may need to be trimmed prior to printing in order to produce square, uniformly-sized press sheets (more properly called trimming), or printed sheets may need to be cut after printing, especially in case where signature pages need to be separated or multiple copies of the same image were printed on the same sheet. Often, printed sheets also need to be cut in order to fit into folders or other bindery devices. Most cutting and trimming is performed on a guillotine cutter, a manual or electronic device with a long, curved heavy knife. A stack of sheets is placed on the bed of the cutter, and the blade cuts through it at the desired position. Some guillotine cutters, especially those used in the trimming of books, use a split gauge, a back gauge divided into three sections allowing for the trimming of three sides of a stack of pages without the need to change the trim setting. In book trimming—usually performed after binding—a three-knife cutter is most often used, which comprises three blades, enabling all the unbound sides to be trimmed simultaneously. The most common knife material is stainless steel, although some cutters—especially those used for special jobs such as labels—utilize carbide inserts. The angle at which the knife contacts the sheet depends on the thickness of the material to be cut. Lightweight papers require a smaller angle, while heavier stock requires a larger angle. Some cutters also utilize high-tech accessories, such as low-pressure air tables, optical cut-line indicators, gripper-loading systems, and tilting-transfer tables, as well as various video monitors and computers, all of which work to increase the efficiency, cost-effectiveness, and quality of the cutting operations. (See Cutting and Trimming.) After cutting, sheets are often placed in a jogger, which is a vibrating table, the action of which squares stacks of sheets.
A folder is an automated device which uses a variety of means to fold sheets of paper inserted into it. Most printing, as was mentioned above, is performed by printing multiple pages on a large press sheets, which are then folded into signatures. There are two basic types of folder, and the choice of folder also depends on the type of fold desired. A right-angle fold involves making a fold in a sheet, rotating the sheet 90º and making a second fold. One fold makes four pages, two right-angle folds make eight pages, etc. A parallel fold involves making two or more folds in a sheet which are oriented in the same direction. Such folds are often made in leaflets, brochures, etc. Some common types of folds include the accordion fold (also known as a fanfold), which includes two or more parallel folds, with adjacent folds in opposite directions; and a gatefold, or two parallel folds made such that the sheet opens from the center. Other specialty folds include the over-and-over fold, the French fold, and the letter fold.
A common type of folder is known as a knife folder, also known as a right-angle folder. On a knife folder—which can have any number of folding stations depending on the ultimate number of folds which need to be made to a sheet—a sheet is carried by the feeder mechanism on a flat plane. It hits a gauge, is positioned by a side guide, and a moving metal blade, or knife, pushes down on the sheet at a right angle to its surface, pushing it down between two counter-revolving metal or rubber (or combination of both) rollers. The action of the knife and rollers creates and "cements" the fold. At this point, the device carries the sheet to additional folding stations, if desired. A jobber is a knife folder has four folding stations and one or two parallel sections, allowing for the making of up to four right-angle folds, two right-angle folds with a third parallel fold, or three right-angle folds and a fourth parallel fold. A double-sixteen knife folder is used in book production and can be used to make two separate sixteen-page units or one thirty-two-page unit. A quadruple, or "quad," knife folder is can be used to make two separate thirty-two-page units or four sixteen-page units. A quad folder is often used in case binding for book production.
A second type of folder is called a buckle folder. A buckle folder uses diagonal rollers to position a sheet against side guides. Feed rollers push the sheet between two metal plates—collectively known as a fold plate—a preset stop in which causes the sheet to buckle. At this point, an additional set of rollers grasps the sheet and forms the first fold. Additional sets of rollers and fold plates make additional folds. A combination folder (colloquially known as a combi) is also used in many folding applications. Generally speaking, knife folders are used for heavier stocks, while buckle folders are used for lighter stocks.
As with cutters, new technologies can be added to folders to increase efficiency, especially by eliminating paper jams and damaged sheets. (See Folding.)
Collating and Gathering
Before binding, cut, trimmed, and/or folded sheets need to be placed in the correct sequence. In the process of collating, individual sheets are organized into sets. Collating is not often a printing or bindery operation, and is more often performed in offices for loose-leaf or mechanically-bound materials. Automatic devices—such as photocopier accessories—are often used for collating. In the process of gathering—which is a printing and binding operation—signatures are organized into sets, often using gathering machines comprising up to thirty individual pockets. Signatures are fed manually or automatically into these pockets, after which they are gathered together for binding. A variation on the gathering process—inserting—involves inserting one signature inside another signature. Signatures that have been gathered and are ready for binding are known collectively as a book block.
There are four basic means of binding sheets together: perfect binding, saddle-stitching (and the related side-wire stitching), case binding, and mechanical binding.
Perfect binding, also called adhesive binding, is a means of affixing pages to a cover or spine by means of glue; an adhesive material is applied to the edges of the book block, and a cover stock is attached on top of it. Common examples of perfect bound publications include paperback books, magazines, telephone books, etc. After gathering, a gluing device applies a film of adhesive (usually a hot-melt adhesive) to the edge of the pages commonly utilizing two applicator wheels. After application of the adhesive, a single-piece cover is applied, where nipping stations tightly press the cover over the book block. After binding, trimmers are used to cut the individual pages of the signatures apart at the top and/or bottom and remove excess paper. In perfect binding, trimming is done following the addition of the cover, as they are often designed to have flush covers, or covers which have edges that are trimmed flush with the interior pages. (See Perfect Binding.)
Saddle-stitching (known with side-stitching collectively as wire stitching) essentially involves the use of wire staples to bind pages together. Saddle-stitching drives the staples through the center of the spine of folded sheets, and is commonly used for magazines, newsletters, and other such publications. A cursory glance at Newsweek, Time, Business Week, or other such magazines will provide an example of saddle-stitching. A less common variety of wire stitching is side stitching, in which staples are driven through the pages from the top of the cover down, usually oriented parallel to the bind margin. Side-stitching is most commonly used for reports, and had once been used for magazines such as National Geographic which are now bound by means of perfect binding.
Signatures to be side-stitched can be gathered and/or collated much like signatures destined for perfect binding, but saddle-stitched signatures must be inserted, or outer signatures laid open on top of inner signatures, which in turn are placed face down on the saddle bar of the saddle-stitching device.
Saddle-stitchers are best used for publications that are up to G inch thick. Individual signatures for a single publication are each placed in a pocket, which feeds the signatures to the saddle bar. There, a spool of wire (the gauge or thickness of which is determined by the binding needs of the publication) is cut into individual staples by a bending mechanism, which can cut staples to the desired size. After forming the staple, it is driven through the spine of the signatures, and a clinching device bends the legs of the staples to secure each staple in place (and avoid injury to the reader). Slitters and trimmers then separate the pages and remove any excess. (See Saddle-Stitching.)
'Thread Sewing and Case Binding'. In contrast to wire stitching, thread sewing involves stitching a book block together by means of thread or cord, often in conjunction with an adhesive. Thread sewing is used for hardcover books, encyclopedias, Bibles, etc. It should be pointed out that thread sewing is the means by which the pages are bound together, while case binding is the attaching of the book cover to the book clock. The most common means of thread sewing is called Smyth sewing, in which a thread is passed through the backfolds of the signatures comprising the book block, which secures the signatures to each other while still permitting the finished book to lie flat.
There are essentially two means of thread sewing, somewhat analogous to saddle-stitching and side-stitching: saddle-sewing and side-sewing. In the former, the more popular of the two, thread is driven through the centerfold of each signature, and each signature is joined to the others. In the latter, the thread is driven through the top sheet down through the signatures and along the edge of the book parallel to the bind margin. In shorter books, a continuous lockstitch or standard sewing pattern is used. In both of these, the stitches are placed in the same position on each signature. The drawback to these stitches is that if there are many signatures, thread build-up can cause swelling of the book. Longer books use staggered or continuous staggered stitches, which move the position of the stitches from signature to signature, reducing thread build-up.
Between thread sewing and case binding, the stitched book block passes through a series of forwarding operations. The first of these are rounding and backing, or a shaping of the book's spine to more securely fit a book cover. Rounding uses steel rollers to impart to the book's spine a concave shape, while backing flares the back of the spine outward, increasing the width of the spine which facilitates the attaching and the security of the case, and also creates the hinges which allow the opening of the book. The process of back gluing coats the edge of the spine with an adhesive material, allowing it to maintain its concave shape. It is also at this point that the tops of the pages receive any edge treatment, such as edge staining, the coloring of the pages of a book, or gilding, the application of gold leaf to the edges of a book. Headbands—or decorative cotton or silk reinforcements attached to the top and bottom of the spine of a book—may also be added at this time. Both these latter operations are optional, and are often only performed only when a publisher feels a book's importance warrants the additional expense.
The final stage is the process of case binding, or attaching a cloth or leather case to the pages. The prelude to casing is smashing (in which pressure is applied to the entire front and back surfaces of the book block) or nipping (in which pressure is only applied to the front and back of the spine), both of which work to compress the book block, forcing out air and eliminating the effects of thread build-up. (Hard papers undergo nipping, while soft papers undergo smashing.) The case itself is created by cutting stiff paperboard to the desired book size and covering it with cloth, the excess cloth then being folded under the boards and glued into place. Cases undergo die-stamping on the spine and/or cover at this time. The process of casing in involves the application of an adhesive to the endleaf papers in such a way that the front and back cover project evenly over the front and back of the book block. The process of building in uses pressure plates and heating elements to dry and set the adhesive.
Many book printers who handle high volumes of book work utilize fully automated printing and binding equipment. Many hardcover—or casebound—books also have a preprinted paper book jacket added at the end of the process. (See Case Binding.)
Mechanical binding is the most basic form of binding, and includes such binding types as comb bindings, in which the teeth of a plastic "comb" are inserted into a series of slits drilled or punched into a stack of sheets, often used for reports and presentations; spiral binding, in which a continuous wire or plastic coil is threaded through holes drilled or punched into a stack of sheets, often used for notebooks; and loose-leaf binding, in which a set of holes (commonly three, but sometimes more or less) is drilled in a stack of sheets, allowing for insertion into standard or customized ring binders or post binders. The advantage of the latter is the easy removal and insertion of sheets. Loose-leaf binding is often used not only for notebooks but also for many types of prospecti, presentations, financial reports, instruction books, and other such uses that may require frequent updating.
Although the term finishing refers to any post-printing operation, including all the above operations of cutting, trimming, folding, and binding, it also refers to specialized decorative processes.
Embossing is a process by which dies are used to stamp a relief image in a book cover or printed material. Often, an ink or other substance is used to color or accent the relief image. Blind embossing, however, uses no decorative inks, keeping the stamped image "as is." A similar process, debossing, uses a die to stamp a sunken image on the substrate. In either embossing or debossing, the substrate passes beneath an embossing plate which carries the engraved die bearing the image. Directly beneath the substrate is a "counter" die, or a die which bears a relief image of the image engraved on the embossing die. When the substrate passes between these two dies and pressure is applied (forcing the two dies together), a relief image is produced on the substrate. (Debossing can occur by simply switching the positions of the two dies, or turning the substrate over.) Often, the dies are heated.
A process similar to embossing (and may also be performed at the same time as embossing) is foil stamping, in which a heated die presses against a roll of foil, contacting the substrate. This transfers the foil—in a pattern corresponding to the design on the die—to the substrate. In foil embossing, the embossing and foil stamping processes are performed simultaneously. Foil stamping replaced the earlier process of bronzing, in which a metallic powder was applied to the surface of a substrate. A type of foil stamping, die-stamping or blanking—is used to press an image into a hard substrate for which embossing is inappropriate, such as a book cover used in case binding.
The process of diecutting uses a different type of die, one which contains knives or creasing rules to cut a pattern into a substrate, or to cut the substrate into a particular pattern.
The dies themselves are prepared and engraved for specific jobs out of a variety of materials and in a variety of ways. See Die.
A variety of coatings can be applied to printed products, either for extra protection or for decorative purposes. (The two uses are not mutually exclusive, of course.) There are several classifications of coatings used in finishing operations: a primer is used to prepare a surface for ink reception or for the application of another type of coating. A lacquer is a combination protective/decorative coating applied to a printed piece. A barrier coating is a protective coating applied to printed packaging, designed to impart resistance to oxygen, water, or other chemicals. Overprint varnish is a high-gloss coating which is added for decorative and protective purposes. Overprint varnish may be applied to the entire surface of a printed material, or to only select portions (in this case called spot varnish).
Coatings are classified according to the means by which they dry. Aqueous coatings are water-based, and dry upon exposure to air, thus requiring a long drying time. Ultraviolet and electron-beam coatings dry upon exposure to ultraviolet light and to beams of electrons, respectively, which cause polymerization of materials in the coating.
The use of specific coatings depends primarily on the nature of the substrate and the ultimate end-use of the material.
Laminating differs from coating in that lamination involves the adhesive bonding of two separate materials or layers of material together. Often, laminating in the finishing sense refers to the sealing of a substrate between two layers of a plastic material.
There are a variety of other types of finishing operations which vary according to the specific requirements of a job. These can include indexing (the addition of plastic index tabs or index thumb cuts to the edges of printed sheets as an aid to locating specific information), padding (the binding of a stack of sheets with a flexible adhesive from which sheets can be easily removed, used in the making of note pads), and other such functions as sorting, numbering, addressing, gluing (i.e., the application of a moistenable adhesive, as in envelopes or labels), or any converting operation.
Off-Line Finishing'. Often many finishing operations are described as in-line processes. This means that these functions are performed by additional units attached to the end of the printing press (especially a web press), allowing the finishing operations to be performed in a continuous process or as an extension of the printing process, eliminating the need to gather up the printed sheets and transport them to another location for finishing. A disadvantage of in-line finishing is that very often makeready time is increased, as is spoilage, as there are more individual operations to set up and prepare. There also is increased downtime with in-line units, since a breakdown at any point in the system shuts down every other system. Many finishing operations are thus performed off-line which although requiring that printed webs be rewound and transported elsewhere, it also means that printing and finishing are not mutually dependent on each other's efficiency. (See Web Offset Lithography: In-Line Finishing.)