"Paper Considerations at the Bindery: Part II"
[Column #78, 6/01]
Grain Direction And Other Issues
I am forever writing about the importance of planning ahead for any binding and finishing job—included in this task is choosing the best paper for your particular project. Paper, after all, is the foundation for all our work. It is the most basic ingredient in printing, binding, and finishing and plays a critical role in the final product. Just as choosing the best paper for any printing job is a given, paper selection for the bindery is equally important.
There are many things to consider when making this decision including weight or thickness, coated versus uncoated, texture, porosity, grain direction, opacity, and color. When it comes to actually binding a book, however; the three most important considerations are grain direction, thickness, and coating. To understand why, consider the abuse each and every piece of paper must endure once it hits the bindery. There are a number of processes that may occur with any given job including scoring, folding, sewing, gluing, and cutting. (And that’s just for binding…finishing may be just around the corner!) We are squeezing, grabbing, mashing, pulling, heating, wetting, and applying glue—all in an attempt to create a perfect book. Something I’m sure most readers take for granted.
Wavy pages due to printing against paper grain direction is one of those issues in adhesive binding jobs that never seems to go away. It’s not surprising since we’re all obsessed with cutting our costs and attempting to achieve maximum efficiencies. We’ve learned the hard way (and the expensive way), however, that going to any lengths to eliminate paper waste can spell disaster. Planning your job with proper grain direction in mind can be critical. In adhesive binding, we strongly suggest that the grain direction of both the text pages and the cover run parallel to the spine. This gives the book better page pull numbers and more flex strength; and the book lays flatter making it more user friendly. Grain direction affects the appearance and durability of each job and it can seriously affect the final cost of the project because it limits the sheet sizes available to you.
In adhesive binding, grain direction is particularly important if the job has been printed on heatset webs and bound immediately. The drying units exacerbate the rippling effect of wrong-grain stock and the paper does not have a chance to get back in balance with the atmosphere. Also, proper grain direction ensures maximum adhesion of hot melt glue in this process. If the job must be run cross-grain, we suggest using PUR glue for the binding. Stronger than either PVA or EVA, PUR’s polymers cross link onto the stock via a chemical reaction with moisture, facilitating adherence, increasing pull strength, and providing greater resistance to hot and cold.
I’m not an expert on case binding so I consulted a colleague of mine, Bob Franzen for input on this matter. Franzen is the Production Manager for Apex Graphic Finishing in Victor, New York, and a 20-year veteran in the case binding industry. He explained, “Grain direction is critical when case binding because the moisture from the end sheet glue will penetrate into the first and last signature. If the spine edge is not parallel to the grain, wrinkling will occur on the first and last pages of the book. Inserting wax paper between the end leaf and first and last pages can minimize this, but can increase the cost by as much as a dollar per book. Some printers will print the first and last signature as a 12-page to avoid this. This is a serious quality problem on coated stocks.”
Franzen went on to say, “Using wrong-grain end leaf or a coated end leaf is a recipe for disaster. Once a wrinkle is formed (which it will with wrong-grain stock), it cannot be pressed out. The curl of a wrong grain end leaf is opposite the travel of the pressing rollers so the problem is compounded. Spoilage will increase dramatically.”
If the grain in both the endsheets and the binder’s board is correct, swelling may also slightly warp the binder’s board. But, again, the strong pressure they are exposed to during the drying process cures this problem and the books come out flat and wrinkle-free. If, however, the endsheets are cross-grain, wrinkles often form parallel to the grain of the paper because the board does not swell in the same direction causing irreparable damage. To worsen the problem, similar waviness can occur when the endsheets are tipped on to the first and last signatures.
Grain direction occurs because paper is made up of fibers (usually from wood but sometimes from other materials such as cotton and linen), giving it a natural “right” and “wrong” direction. While printers obviously know how to test for grain direction, many print buyers do not. In a time where tree-free and other fancy, design-oriented papers are becoming increasingly popular, it’s not always easy to know the true grain direction of a stock. Here are some simple tests you can share with your customers:
Moisture test. Wet one half of the sheet with a sponge. When it dries, the direction of its curl points to the grain direction. (Since wetting the paper at the bindery with glue and other substrates is an everyday occurrence, this test also reveals the inherent problems that come with working against the grain. The moisture in the glue causes waves in the paper if the grain is not parallel to the binding.)
Folding test. Crease the sheet both longitudinally and laterally. The direction in which it folds most easily and the crease is the sharpest is the direction of the grain. For many people in the business, simply bending the sheet will reveal its grain direction because folding it against, or perpendicular to, the grain is much more difficult than folding it with the grain, or parallel to it.
Tear test. Tear the sheet both longitudinally and laterally. Whichever direction tears more easily and cleanly is the grain direction.
Grain Direction for Scoring and Folding
Grain direction also plays an important role in folding and scoring. This is particularly true in planning imposition for the cover stock of saddle-stitched, perfect bound, and smyth sewn softcover books and for presentation folders. Because the heavier stocks that are used for covers and folders are almost always scored to ensure a clean fold, the grain should always run parallel to the score/fold.
For other types of folding jobs, keep in mind that folds that are right angle from the first fold can either be scored or wet-scored on the folder. If you must fold against the grain, consider a stock with short fibers and “off-machine” coating for better moisture control.
I’m laughing to myself right now because when I began writing this article, I had concerns that there might not be enough meat to do a full column. I barely got through grain direction! Looks like this is going to be two-parter. Next month, I’ll cover paper coatings and other issues surrounding paper selection and their affect on various specialty post-press finishing options.