Paper from the Bookbinder's Point of View
Paper serves as the essential base for all printing and binding, providing the canvas for every image. Choosing the right paper type, weight, coating, texture, grain direction, opacity, and colour is crucial in planning a printed piece. Just as the printed image influences paper selection, the specific bindery needs must also factor into the choice.
Paper consists of fibres, primarily from wood, though cotton, linen, and other materials are also used. Researchers continue to explore alternative fibre sources, such as bamboo, hemp, and rice straw. Clay or other materials can also be added to the fibre base to create coated papers.
For bookbinders, grain direction and coating are critical paper traits. Throughout the binding process, we handle paper intensely: passing it through knurled rollers, gripping it with mechanical fingers or suction, pressing it hydraulically, heating, wetting, and applying various types of glue. Binding steps—scoring, folding, sewing, glueing, and cutting—are all impacted, sometimes significantly, by the paper’s characteristics.
Grain
Grain is important both to the printer and the bookbinder. Your job must be planned from the very beginning with grain direction in mind. This can affect not only the appearance and durability of your book, but also the sheet sizes available to you–and thus press size, yield, and cost.
You can discern the grain direction of a piece of paper in several ways. Simply bending the sheet is usually indication enough–the paper is much harder to fold against (perpendicular to) the grain than with (parallel to) the grain. One surefire way to determine grain direction is to lay a small sheet of the stock gently onto the surface of a pan of water. This wets one side of the sheet, while the other side stays dry. The paper fibres will swell on the wet side and cause the sheet to curl up into a tube–the length of the tube is the grain direction. This simple test illustrates one reason why grain direction is so important to the bookbinder.
Grain and Glue
When binding a hardcover, case-bound book, we apply water-based glue at various stages of production. A thin bead of glue attaches the end sheets to the first and last signatures. During “casing-in,” when we connect the text block to the cover, we coat the entire outside of each end sheet with a thin film of glue. This glue dampens the paper, causing the fibres to swell perpendicular to the grain direction. To avoid unwanted curling of the endsheets as we case in the books, we immediately place the hardcover over the outside of the book and press it into the glue. To prevent wrinkling, we apply firm pressure until the moisture evaporates and the glue fully dries.
If the grain on the end sheets is correct–i.e. parallel to the binding edge of the book–the swell in the grain may warp the binder board (which has its grain in the same direction) slightly, but as the glue dries with books under pressure the swollen grain shrinks and this tendency relaxes; books emerge from the press flat, with no wrinkles in the end sheets.
Scoring, Grain Direction and Folding
Grain direction is also a critical issue when imposing cover stock for saddle-stitched, perfect bound, or Smyth-sewn soft-cover books or presentation folders. The heavier stocks used for covers and folders are virtually always scored to facilitate clean, reliable folding. Again, the grain should run parallel to the fold/score for the best result. Covers imposed against the grain may need special letterpress scoring, and even then may not behave well.
Coated vs. Uncoated
Adding clay and other mill coatings to paper changes both its appearance and its performance from the pressroom to the bindery. For binders, these coatings influence scoring, folding, and glue compatibility. Coated stocks often carry heavier ink coverage and additional protective coatings like varnish or UV, which can impact the binding process.
Clay-coated stock, for example, wrinkles more easily when dampened by the glues in case of binding, making it less ideal for end sheets. Even the text portion of a book printed on coated stock can wrinkle during casing-in without careful handling.
For hard-cover books with printed covers, film lamination provides the necessary strength for the paper to serve as the case’s hinge. Without this reinforcement, paper—even with UV or other coatings—may tear quickly at the hinge. Ideal stock for a film-laminated case includes 80 or 100 lb. coated bookweight paper with a glue-compatible film laminate on the outside only. Several manufacturers now offer heavier uncoated stocks suitable for both lithography or foil stamping and use as case material.
Perfect binding on coated text stocks can be challenging, as hot melt glue doesn’t adhere well to these surfaces. To ensure durability, it’s best to Smyth sew these books before attaching the covers. For cover stocks, both coated-1-side (C1S) and coated-2-side (C2S) perform well on the perfect binder.
Board
Some details about the paper also apply to the binder’s board. Like paper, a binder’s board is made from pulped fibres and has a defined grain direction, which plays an important role in binding. Although binders don’t often score or fold this board, they ensure the grain direction runs parallel to the book’s binding edge. This setup minimizes any warping during the binding process, so any bend in the board will simply cause the cover to open slightly rather than damage the book’s binding.
