Planning for perfect-binding crossovers is part art and part science. In addition to grinding 1/8-inch off the signature spine, accurate crossovers depend on your layout and how the books are opened.
For maximum operator flexibility, place your crossover images 3/16-inch from the spine edge. Your crossover should appear to meet right at the spine. To achieve this effect, strip your copy 1/16-inch short of the grind-off area. If your book is thick or is printed on heavy paper, nudge the image outward, perhaps another 1/32-inch. If your book is thin, nudge the image closer to the grind-off area. In general, diagonal lines are among the toughest to visually line up.
Two-page forms
Avoid two-page forms if possible. When you can’t, bury them somewhere in the middle of your book. Because they look so good, fly sheets are common. When bidding on books with fly sheets, such as annual reports, advise your customer that the perfect binding machine may run between 25 per cent to 50 per cent slower than normal. However, because fly sheets hardly impact make-ready times, small job quantities rarely are a problem. As quantities increase, though, poor production speed becomes an issue. When selecting your fly sheet, remember that the slicker the paper surface, the further your glue will spread.
More tips
The following are more important tips that you can use when perfect binding:
Perforated signatures reduce paper wrinkling and improve clamp grip. Plan your perforations to pass the low-tech “finger-flick” test. They should be numerous enough to easily let out trapped air, but not so deep that the sheets separate upon a light flick of the finger. When you need stronger glue adhesion, consider notch perfect binding, which creates small serrations that are cut into the spine of a perfect-bound book.
The downside of the notched book spines sometimes acquire a nail head appearance where the glued edge is thicker than the book. Experienced perfect binding companies, however, armed with the latest in glue technology can usually achieve excellent adhesion results on most projects with normal perfect binding. Cover weight sheets used as text can be difficult to get sufficient page pull strength. In these cases, consider side stitching as an alternative to sewing because it is usually more cost-effective and stronger.
Coffee table books and other long-lived products are good application examples. For an eye-catching design idea, consider tape adhesive binding. Tape binding is colourful, strong and unique.
Changing stock during a signature run can create a bindery mess because book block thickness must be considered to ensure the proper functioning of clamps and electronic sensors. Some mistakes can be very costly. It’s a real shame whenever perfect bound books are stripped with saddle-stitching layouts. In order to save these poorly-conceived books, they must be gathered on a saddle stitcher, cut in half along the spine and re-collated. Needless to say, this is very inefficient, the quality is poor, and the price is astronomical.
Production trick with foldout covers
Normally, foldout covers need to be undersized by 1/8-inch from the face so that the foldout panel isn’t trimmed off. However, with a double pass through the perfect binder, you can overcome the resulting 1/8-inch gap.
First, bind the book block and trim the face. Then, apply the cover to the book and trim the head and foot. The result is a beautiful, perfect-bound book product with the foldout cover flush with the book face.
Foldouts: For gatefolds, half-cover folds, roll folds, map folds, and so forth, allow for the proper grind-off margin plus an extra 1/8-inch so your foldout doesn’t get glued. Also, give 1/8-inch face-fold margin so your fold isn’t trimmed off during the face trim. Providing less of a margin reduces our binding operator’s ability to make adjustments for such elements as crossover image positioning. Similarly, glued pockets on the inside back cover also need 1/8-inch foot and face clearance. It’s a good idea to check with us to ensure your foldouts will feed properly in the loading pockets.
Product durability
Inside cover copy: For maximum adhesion between cover and text, your ink and paper coatings shouldn’t enter the inside cover’s hinge, score and spine areas. If a full bleed image is used on the inside front cover, a 1/16-inch overlap into either area should be acceptable.
Paper coating: Beware of flood coatings. Aqueous, UV, beauty coat, varnish, web-applied silicon, as well as regular ink all reduce glue adhesion. Glue must directly contact exposed raw paper fibres to create a strong bond. Spot-coating your images is fine as long as your coatings don’t enter the gutter margin. Give us production flexibility. Keep ink and paper coatings 1/8-inch away from the gutter. Although 1/16-inch may be acceptable, a full 1/8-inch allows adjusting the grind-off margin for best copy appearance.
