Introduction

For many years, oversewing has been called the cornerstone of library binding. Oversewing does provide an extremely strong, durable and relatively economical method of leaf attachment. In fact, since oversewing has been recognized as the strongest method of affixing leaves, it is not surprising that many library binders have chosen oversewing as their preferred method of leaf attachment.

It is unreasonable, however, for anyone to claim that oversewing is the best or only method of leaf attachment to be used in quality binding. The premise that strength and quality are synonymous loses validity, if one recognizes that strength must be traded off against flexibility, to allow effective use of the book. This point is especially relevant when poor quality paper or narrow margins are involved.

This is not to say that oversewing is not a good choice. On the contrary, oversewing is an excellent method of leaf attachment, as long as the paper condition is good and the inner margin is adequate. The argument for oversewing is even more persuasive if the book is expected to circulate frequently.

The strength, assurance of secure attachment of all pages and relative cost advantages (as compared to other sewing techniques) will always insure that oversewing remains a necessary and significant option for both the library binder and the customer. The important question, though, is how much strength does one need and when is strength the first priority? It is important to note that the full assortment of leaf attachment techniques available must be utilized to solve the many binding problems we face. Machine sewing, centerfold sewing and adhesive binding are several of the tools available to do the job.

Prior to the selection of any binding method, each book should be screened thoroughly, taking into account the following factors:

• paper quality;
• width of inner margin;
• presence of an acceptable sewing structure; and
• format of the leaves (i.e., single sheets or folded sections).

Once this examination has been made, a leaf attachment method can be chosen that will not only allow the bound book to be read and copied comfortably, but will still leave it as strong as possible. Whether concerned with new books, rebinds, or periodicals, the customer and binder together must determine who is best qualified to assume the responsibility for this screening and clearly defined guidelines must be mutually agreed upon. Both parties need to consider the assets and liabilities of each option, including:

• openability of the book;
• necessary spine loss;
• relative cost;
• ability to copy pages;
• strength of the resulting binding; and
• options for rebinding.

In particular, the expected use of the book and the cost constraints imposed by the customer are major concerns that must be immediately identified so that a proper binding selection can be made.

Methods of Leaf Attachment

Letís look at eight different methods of leaf attachment: six sections involving sewing and two using adhesives.

Leaf Attachment by Sewing

Oversewing

Machine oversewing was first introduced in 1920 and has since become the primary method of leaf attachment used by library binders. This method requires that each book be divided into small sections of individual pages or leaves. Often, this is accomplished by milling or cutting the spine of each book to remove the glue and/or original sewing. In some cases, a binder may elect to take a book apart by hand with a knife. This operation accomplishes the task of dividing the book into small sections (approximately 15-20 pages each) without loss of inner margins and generally results in an extra charge. Books receiving normal spine preparation on a milling machine lose up to 1/8 inch of their inner margin. Precautions must be taken to ensure that all books designated for oversewing have remaining inner margins (after spine milling) which equal or exceed 5/8 inch. After spine preparation, the books are ready for the oversewing process. Sections of the book are placed into the machine at a 45- degree angle and are then clamped. Vertical punches (spaced 1 inch apart) punch holes through the pages of each section. Threaded needles pass through the punched holes, enter through the spine and exit the section approximately 3/16 inch in from the back edge of the page. Horizontal shuttle needles then pass through each of the separately formed thread loops and complete the stitch. The process is repeated to form successive lock stitches up the spine of the book.

Major Advantages of Oversewing:

• Versatilityóany book up to a 15 inch height, unlimited width and five inch thickness can be oversewn.
• Strengthóthe lock stitch sewing provides exceptional strength.

Major Disadvantages of Oversewing:

• Perforation of pages inherent to the process can (and will) damage poor quality paper.
• Rebinding a book once oversewn necessitates either cutting off º inch from the spine or manually taking the sewing apart. This is rarely necessary because of breakdown of the sewing structure, but may be required for other reasons, such as book mutilation or insertion of missing issues (with periodicals).

Sewing Through the Fold by Hand

This technique has been used with great success for centuries and has few (if any) disadvantages, other than its relative cost. The process requires that the pages of the book to be sewn are in folded (or signature) form. Hand sewing is accomplished by passing a threaded needle through a hole in the folded section of paper, starting from the outside (or back edge) of the signature.

The needle draws the thread along the fold, parallel to the spine and passes it back out through another hole. After looping around a cord or tape, the needle passes back into the folded signature through yet another hole and the process is repeated until the full length of the spine is sewn. The beginning and end of each signature are tied off with a kettle stitch to attach the signature at hand to the one previously sewn. This entire process is repeated for each additional signature. The last section is the endsheet, which is comprised of two folded sheets with a cloth reinforcement strip at the fold of the outer sheet. The cloth reinforcing strip is usually attached only to the outside edge of the fold and extends 1/8 inch beyond the fold. This free cloth extension can be tipped to the adjacent page of text, thereby providing a hinge between the text block and endsheet. After sewing, cords or tapes are cut off approximately 1 inch beyond each side of the spine and are glued down securely with adhesive. Sewing on tapes is preferable to sewing on cords. Tapes are external to the text block and allow the book to open completely flat. Cords are usually recessed within saw cuts in the spine of the volume restricting the opening of the book (especially for thick signature books). When hand sewing, it is possible to have sections of pages that are comprised of single sheets, as well as folded signatures. These are sewn together through the side, similar to oversewing. The sewer can alternate within a single book between sewing through the fold and sewing through the side, as necessitated by the material at hand.

Major Advantages of Sewing Through the Fold by Hand:

• No spine milling is necessary.
• Completely flat opening, allowing both easy reading and copying of text that runs near or across the center fold.
• Only minimal spine damage is caused by hand sewing. The center fold attachment of pages results in minimal stress placed on the pages when reading. This method is considered gentle to the book and should lengthen its life.

Major Disadvantages of Sewing Through the Fold by Hand:

• It is a slow hand process that is unavoidably expensive. Consequently, cost conscious customers cannot always justify hand sewing for all materials.
• Fewer and fewer books are printed in signature form, thereby eliminating this option from the range of potential leaf attachment alternatives.

Sewing Through the Fold by Machine

The machine most commonly used in library binderies for centerfold sewing is the Smyth-National sewing machine. The Smyth-National is a modified edition bindery machine, which can better accommodate the variety of different materials processed in a library bindery each day. Its operation in many ways duplicates that of hand sewing, with the major difference being that the book is sewn with multiple sewing heads, simultaneously sewing each folded section. Rather than having a long series of continuous horizontal stitches through the fold of each section, there is an independent series of stitches formed within each signature and connected vertically between signatures.

Major Advantages of Sewing Through the Fold by Machine:

• Lower cost, relative to hand sewing.
• All other advantages of hand sewing apply.

Major Disadvantages of Sewing Through the Fold by Machine:

• Most machines have constraints not encountered when sewing by hand. For example, the machine cannot sew folded sections that are less than three folded sheets (or more than approximately º inch thick).
• No machine can sew a combination of single sheets and folded signatures.

Recasing

This method is generally chosen for books where the original sewing remains intact and it usually applies only to books that are complete in one piece. After removing the original cover, the old backlining and the old glue, it is possible to inspect the sewing to determine if it is still sound. Proper spine preparation is essential. In publishersí bindings, animal glues are often used on the spines because of their compatibility with high speed, automated binding processes. Unfortunately, animal glue becomes brittle with age and does not enhance the quality of the Smyth sewing with which it is often used. After the spine has been cleaned, defects in the sewing (which were covered by the old glue and spine lining) become apparent. At this point, a book with unsound sewing would be rerouted to one of the other leaf attachment work stations. Books that are sound have new endsheets attached, get a coat of specially-formulated polyvinyl acetate (PVA) emulsion glue and a new spine lining cloth is applied. The PVA adhesive is internally plasticized and does not lose its flexibility with age. New endsheets are attached, via one of several methods. First, there is the stab sewing process. New endsheets are sewn onto the text block by passing a threaded needle through the tab of an oversewn endsheet, then through the book, at approximately a 45-degree angle. The needle then passes back through the spine and out through the endsheet. This process is repeated down the length of the spine and back again so that the stitch can be tied off. An attempt should be made to vary the angle of penetration and the exit and entrance locations along the spine, so as to reduce the stress to any one part of the spine. The endsheet is folded back onto itself to cover the sewing and to provide a hinge which is even with the back edge of the book. Although this method does preserve the original centerfold sewing, in effect, it oversews the first and last sections of the book and introduces all of the drawbacks of oversewingówithout the cost reduction of a machine operation. It should be used only for oversewn volumes that are being recased. A second method uses specially designed, but commercially available, endsheets. This technique should be used on recased volumes comprised of sewn, folded signatures. It uses the same process as the Smyth-National sewing method does, but is performed with a hand operation. A threaded needle is passed into and out of the last secure section of the text block, leaving a loop extending at each point of entry into the signature. The entrance and exit locations of the needle through each signature must align vertically so that the loops left from the previous signature can be sewn through and drawn tight, thus forming a series of connections between signatures. This process is repeated for each signature added. The endsheet is sewn on in exactly the same way. This forms an unrestricted cloth hinge between text block and endsheet.

Major Advantages of Recasing:

• Books with narrow margins, poor paper quality, or intrinsic value can be rebound in a nondamaging way that utilizes the existing sewing.
• Books will open easily both for reading and copying.
• This method is less expensive than hand sewing, but produces the same results.

Major Disadvantages of Recasing:

• Much handwork is involved and, therefore, extra charges are incurred.
• The binding is only as good as its original sewing and cannot be expected to be as durable as bindery sewing through the fold.

Side Sewing (also known as Singer Sewing)

This method is not used extensively by library binders because of mechanical and functional limitations. The side sewing process sews books through the side with a chain stitch, much the same as a conventional sewing machine sews clothing. Unlike other sewing methods, the side sewing method sews the entire book as one section. A threaded needle enters the side of the book at a 90-degree angle and exits through the bottom of the book, where the stitch is caught by a bobbin thread.

Major Advantages of Side Sewing:

• Exceptionally strong.

Major Disadvantages of Side Sewing:

• Limits the openability of the book.
• Books must have inner margins of more than 1 inch and must be no more than ‡ inch thick.

Cleat Lace Binding

It is generally regarded as a technique to be used only for storage bindings and books where durability is not critical. Cleat laced binding (like oversewing) requires that the spine first be cut to separate the book into single sheets. Next, parallel slits or cleats are cut into the spine of the book by circular saws at opposed angles. These cleats cut into the spine approximately 1/8 inch. A thread carrier then separates thin sections of the paper to lace a pasted thread around the cleats in a figure-eight pattern. The final strength of this process is achieved only when the spine is coated with PVA adhesive.

Major Advantages of Cleat Laced Binding:

• It is a faster and simpler method of leaf attachment and should provide a less expensive alternative to other sewing options.
• Openability is somewhat better than with oversewing and side sewing, but not as good as with some of the other methods mentioned.

Major Disadvantages of Cleat Laced Binding:

• Essentially the same spine loss is incurred as in oversewingó1/8 inch for milling and 1/8 inch for the cleats.
• Testing has shown that strength and durability are inferior to oversewing and double-fan adhesive binding, especially in the front and back sections of the text block.
• Rebinding requires cutting off an additional º inch to duplicate the cleat laced process.

Leaf Attachment by Adhesive

Adhesive binding, as it is done today in the library bindery, should not be confused with "perfect binding" as done in the edition bindery. Although it is fast and inexpensive, "perfect binding" (which is really a misnomer) is subject to failure with age and use. Other types of adhesive binding do not share the disadvantages of "perfect binding" or the lower cost relative to sewing and, therefore, should not share their negative connotations.

Double-fan Adhesive Binding

Double-fan adhesive binding is the technique used by most library binders, using either the Ehlermann Double Fan Binding Machine or a similar hand process. This process requires that the spine of the book first be milled to remove glue and/or sewing from the text block. It is essential that the milling operation cuts the spine of the book, so that each and every page of the book is flush. After milling, a fanning clamp grips the book and later, the milling clamp is released. This double clamp process (made possible with the use of the Ehlermann Machine) ensures that the alignment of pages created by the milling process is not disturbed when the book is transferred to the gluing station. After making sure that all of the pages of the book are separated and free to fan independently over the glue roller, the next step begins. The double fanning operation first fans the book down over a glue roller that applies a thin line of PVA adhesive to each page as it "fans" free over the roller. This penetration of adhesive between pages (approximately ten thousandths of an inch) actually tips one page to another. At the end of the downward cycle, the process is repeated in reverse. Some binders fan each book twice. In effect, they produce a double-double fan binding. Each side of each page would fan over the glue roller twice, for a total of four applications of glue for each individual page. Following the spine fanning and gluing, a piece of stretch-cloth back lining is applied to the spine, extending to the front and back endsheets. This back lining covers the glued spine and enables the operator to remove the book from the machine clamp without disturbing the page attachment. The normal drying period should be at least several hours before any further handling takes place. Double fan binding demands careful attention to the alignment of the pages after milling and before fanning. If a page is not jogged flush to the surface of the spine, it will not touch the glue roller and, thus, will not be glued. Just as important is the quality of the glue used in the process. Since the adhesive is all that holds the page to the book, it makes sense to use the best product available. The PVA products that have earned this distinction are of German manufacture and, to date, have not been duplicated or improved on domestically.

Major Advantages of Double-Fan Adhesive Binding:

• Completely flat openability of the book, allowing both easy reading and copying, regardless of margin.
• Very little spine milling is required, therefore allowing rebinding with minimal difficulty
• Strength is unusually good, especially if the paper stock is anything other than heavily coated paper.

Major Disadvantages of Double-Fan Adhesive Binding:

• Books in signature form must have the spine folds cut before fanning. For thick signature books, the necessary cuts may have to be quite large.
• Stiff and/or cross-grained papers are not well suited to double-fan adhesive binding.
• Heavily coated papers do not allow the adhesive to penetrate into the paper fibers and the resulting bond is less strong.

Mekanotch Binding

The Mekanotch machine has been successfully used in Europe for close to a decade, but is just now being introduced into library binding in the United States. The Mekanotch machine cuts thin slits in adjustable patterns and (more importantly) in adjustable depths of penetration into the spine of the text block. This notched pattern prepares the spine for optimum linkage between paper and PVA adhesives by increasing the surface area with which the glue will come in contact. Deeper notches, although they allow greater adhesive penetration and strength, will result in a book that is more difficult to open. The trade-off between strength and flexibility cannot be ignored. The notched pattern can and should be adjusted for maximum advantage. Notched binding can be a stand alone process. After notching and spine milling, the book can be glued with PVA adhesive for an acceptable quality binding. Special care must be taken to insure that PVA adhesive is forced into all of the notches. It is important to note that notched binding as a stand alone process is, as yet, untested and cannot be recommended for permanent library materials.

The Mekanotch process can also be used in conjunction with double-fan adhesive binding to produce optimum strengthí and flexibility. In the past, problems such as incorrect paper grain direction, stiff paper and heavily coated paper have made many binders reluctant to choose adhesive binding, when margins are narrow. Mekanotching, for the first time, allows the binder to control spine preparation to the extent that any book can be adhesive bound with confidence. The notches cut into the spine of the book are quite thin. These notches can be spaced at varying intervals to either maximize strength or minimize paper damage. The combination of individually tipped-together pages and greater spine contact with adhesive will result in an adhesive binding superior to any other now available.

Major Advantages of Mekanotch Binding:

• Especially when used with double-fan adhesive binding, can provide strong and flexible bindings regardless of margin.
• Notch depth and spacing are adjustable, meaning that binders can control spine preparation, minimizing damage and maximizing strength as desired.

Major Disadvantages of Mekanotch Binding:

• Since it is new to the United States, it is not yet available in many binderies.
• The greater the linkage between the paper and the PVA adhesives, the more flexibility is sacrificed. Bindery must use reasonable judgement in determining depth of notches.

Conclusion

Now that you have had the chance to review brief explanations of eight complex, technical methods of leaf attachment, you can better understand how difficult it is for library binders to strike a balance between acceptable quality and customer-imposed cost constraints. Full implementation of the procedures outlined on these pages require that the binder:

• Maintain an inventory of up to four different types of endsheets;
• screen incoming books to determine the appropriate method of attaching leaves;
• route books to the various selected work stations; and
• reassemble the books into a complete job lot before moving them to the next stage of production.

This routine requires considerable effort by the binder. Even if the customer is willing and able to indicate the leaf attachment desired for each book sent to the binder, someone at the bindery must reevaluate that decision. This is because it is not always possible to determine the strength of an existing sewing structure in a book until the old cover is removed and the spine is cleaned. Wire staples and previous leaf attachment treatments often make it difficult to determine the width of the inner margins.

Itís important to remember that the primary function of a binding is to hold the pages together within their protective cover, allowing convenient storage and easy access to the printed text. Factors beyond the control of the customer and binder often make it impossible to find one single solution to the problem of how best to attach leaves. Fortunately, library binders have the expertise, the facilities and the commitment to successfully utilize a variety of techniques, balancing quality, strength and cost. The customer and the binder should mutually determine a leaf attachment guideline that considers:

• paper quality and available inner margins for each volume;
• what margin breakpoints will be for each method;
• what bookís ultimate use will be;
• what the customer can afford in each case; and
• what charges will be incurred for hand work, if necessary.

Leaf Attachment Guidelines

An initial guideline for selection of possible methods of leaf attachment could be as follows:

1. Any book with up to 5/8 inch inner margin could be:

• Recased (extra charge);
• Sewn Through the Fold (extra charge); or
• Double-fan adhesive bound with spine notching.

2. Any book with over ‡ inch inner margin could be:

• Recased (extra charge)órecommended for poor paper or valuable books;
• Sewn Through the Fold (extra charge)órecommended for poor paper books, books with thick signatures, or valuable books;
• Oversewn (if paper conditions permits)órecommended for heavily circulated books; or
• Double-fan adhesive bound with spine notching.

Books foster communication between strangers. Binders and their customers are not strangers and should not treat each other as such. Itís vital that a continuing dialogue be maintained, so that the best possible binding decisions can be developed. Hopefully, this information will help to assist such a process.