Paper Grain: Enhances or Impedes the Function of a Book

There are many steps to designing and constructing a book that functions well in the hands of a reader. Considering the properties of each component used in the book’s construction will have a significant influence on its performance. In Preservation Services, we are most often repairing books rather than creating new bindings, so we inherit the bookbinding decisions made by a book’s original creator, whether good or bad. As we determine the best method of repair, we consider both the aesthetic outcome (how a book will look) as well as the function of the book.

Photo by Brandi Redd on Unsplash.com

The type and quality of paper used in the binding can affect how long a book will last over time. One of the recurring issues conservators face are brittle books. Between the 1850s and 1980s, the publishing industry sought ways to produce large quantities of books that were cheaper to manufacture. Books printed on wood-pulp paper were among the ill-fated results as the process of making the paper left it destined to become more acidic over time which causes the paper fibers to break down and become weak. Surprisingly, a book made during the Renaissance era might be in better condition than a book printed in the 1950s due to the type of paper used.

Brittle book
(Image: https://psap.library.illinois.edu/collection-id-guide/paper)

Additionally, the way the paper is used in the binding has a substantial influence on how the book will operate, such as how the book will open and close or how easily the pages will turn. Just like wood, paper has a grain direction to it. As paper is made, whether handmade or machine-made, the fibers generally align vertically or horizontally due to the motion of how a papermaker forms the sheet or how the fibers are extruded from a machine.

Making paper by hand
By Hahnemühle PR (Own work) [CC BY-SA 3.0
(https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

It is usually a simple task to identify the grain of a sheet of paper, though in some paper it is difficult to determine. If you have ever tried to tear a coupon out of a newspaper, you have likely experienced the blessing and curse of paper grain. In one direction, the paper is easy to tear straight but in the other it has a mind of its own. When tearing with the grain direction, it is much easier to make a straight tear.

Left: Tearing with the paper grain, Right: Tearing against the paper grain
(Blue arrows indicate grain direction)

Another method of determining the grain of paper is to bend it as if you are about to fold it. When you bend against the paper grain, the paper is more resistant to the pressure of your hand. When you bend with the grain, the paper seems much more cooperative with the folding process. 

Testing the paper grain

Similarly, folding and creasing with the paper grain creates a much tidier fold than when the paper is folded against the grain.

Left: Folding against the paper grain, Right: Folding with the paper grain

So, how does paper grain affect the function of a book? The rule of thumb with grain direction in bookbinding is to make sure the grain of all your materials (book board used to make the covers, book cloth covering the book, and any other material with a grain used in the construction of a book) is running parallel to the spine of the book. Not only will the paper fold more easily and neatly if the grain direction is parallel to the spine, but it also affects how well the book opens and its ability to adjust to environmental changes like humidity.

Pages do not drape properly because the grain direction
is perpendicular to the spine of the book

Pages with correct grain direction drape open more easily

As a book is fully opened, the pages should easily turn and lay down without extra effort from the reader. In bookbinding, this is referred to as the drape of the book. If the pages drape nicely, the grain direction of the pages is likely parallel to the spine. If the pages must be held open or even stand up on their own, the grain direction of the pages is likely perpendicular to the spine.

When grain direction is wrong, a book exposed to humidity ripples
and dries because it is restricted by sewing or adhesive at the
spine and cannot swell and shrink freely.

If the grain direction is wrong, the pages are not allowed to shrink and swell with changes in humidity. Paper swells when it takes in moisture from the air. Perhaps you have noticed ripples in the pages near the center of a book where the pages are sewn or adhered at the spine. Usually, this is a result of the book experiencing increased humidity. The paper swells but has nowhere to go, so it ripples and dries. If the grain direction is parallel to the spine, the pages can swell outward from the spine when it is more humid and shrink back to normal in drier conditions.

Rippling along the center of the pages indicates
the paper grain is likely perpendicular to the spine,
which impedes proper function of the book.

Though we can’t change the grain direction in a book that arrives in Preservation Services to be repaired or restored, understanding its impact on the function of a book is helpful as we determine the best solution for its repair.