Mechanical bindings offer many features that traditional bindings don’t. They universally lay flat and most can even be opened far enough to display just one page with the other pages tucked under the open book.
These bindings aren’t suitable for most books however. Because the book title is generally not displayed on the spine, many bookstores won’t carry them. Since the spine of the book is usually wider than the book, it presents other retail display problems. And since the cost per book approaches or even surpasses the cost of case binding, many publishers feel the added cost will diminish sales because case binding usually carries a higher perceived value than mechanical bindings.
The most popular mechanical binding is plastic comb binding, sometimes called GBC binding after the company that popularized it. Plastic comb binding is the binding of choice for many fund-raising cookbooks. It is available in a variety of colors, and the title can often be displayed on the spine (at additional cost).
Plastic combs have been known to become brittle if left out in the car overnight during extremely cold weather. I’m reminded of the professor who proudly dropped ten plastic-comb bound copies of his textbook on his desk the day after picking them up, only to have the combs crack, break, or shatter. Many comb manufacturers say that this is no longer a problem, but it would be wise to get some assurances from your book manufacturer before specifying plastic comb in colder climates.
Spiral wire is another popular choice we’ve all come to know. Nearly everyone has folded a spiral wired notebook back on itself to take notes in school. Also remember what happens when the wire at the head or foot become deformed to snag sweaters and inflict bloody scratches. Worse, the metal can be squeezed from a round shape that allows pages to turn easily to an elliptical shape that makes page turning a cumbersome maneuver.
Spiral wire is one of the less expensive mechanical bindings as there are a number of automated application systems, and the wire is relatively inexpensive.
Plastic spiral wire is available with some advantages over metal...namely its inherent memory tends to avoid distortion, keeping the ends in place and rebounding to a circular shape after sitting under a load of heavy books. Plastic is available in a number of colors.
The most expensive common mechanical binding is wire-o or double loop binding. Although it has excellent lay flat characteristics, like plastic comb, it can only be opened around on itself with difficulty. It uses a heavy, less flexible metal wire that cinches closed on the pages, but since the wire ends are stronger than spiral, they tend not to protrude away from the book, and the spine resists distortion much better than spiral wire.
Wire-O works with paper covers, plastic or vinyl covers, cloth covered boards, and even offers a concealed or exposed printed spine.
All of these options are available for a price that may quickly surpass comparable case binding, but with substantially different characteristics.