Proper folding, scoring and binding of paper are mostly a matter of understanding the major properties of paper fiber. One of the most important properties to understand about paper fiber is grain direction, - the direction in which the fibers align on a specific sheet of paper. Yes, that pesky little grain direction issue which is stated in so many swatch books, printing guides and all over paper mill literature really means something, and you should understand it whether you’re a graphic designer, printer or a home hobbyist. If you work with paper, know which way the grain flows.

Grain direction unraveled in 148 words

A quick “Paper 101” on grain direction. As paper is made, all the fibers within the pulp stew begin to line up in the direction in which the paper machine is moving. The cellulose fibers align, side by side, much like logs floating down a river during turn-of-the-century logging. The end result is that many more fibers than not are pointed in the same direction along a sheet of paper, forming a “grain direction.” Typically when using an 8.5” x 11” sheet of paper, the grain is in the 11”, or the “grain long,” direction, meaning that the vast majority of fibers are aligned parallel to the 11” length of the paper. In contrast, if the sheet was cut “grain short,” then most of the fibers would be pointing across the short side of the sheet in the 8.5” direction, or what is called the “grain short” direction.

About the author: Phil Schumacher has a BS in Chemical Engineering from the University of Wisconsin-Madison and an MS in Chemical Engineering from Purdue University. He has more than 20 years of experience in the paper industry in various engineering and management roles. Prior to joining CTI Paper Group, Inc. in 2003, Schumacher was with Gilbert Paper / Mead Corporation for 14 years. Reach him at 920-720-3192 or schumacher@thepapermill.com

OK, now you know

Paper has a grain direction. So what? We all have our issues, right. Now hold on, it’s not that easy. Grain direction is very important and makes a huge difference as to how the paper will react when you attempt to fold, score and bind it. Therefore, knowing the grain direction and how it will affect the layout of your project makes a big difference in the quality of your finished piece. A few minutes spent learning about and understanding grain direction will help you for years to come.

Folding and scoring with the grain direction

Knowing why grain direction is important will help you as well. As a visual aid to the grain direction concept, think of paper fibers as a dozen wooden pencils, lying side by side on a table, forming an imaginary sheet of paper. If you would like to fold this imaginary sheet of paper, you can easily imagine that folding in the parallel direction to the pencils is easiest. Fold across the parallel direction of the pencils, and the pencils will all snap in two. While not exactly the same in paper as with pencils, the concept does illustrate that the best way to fold and score paper is with the grain direction parallel to your fold and score. Fold and score parallel to the grain, and you will break fewer fibers and have a stronger and cleaner fold or score. You can easily demonstrate this for yourself by taking a light cover stock, perhaps a 65 lb. cover, and folding it the length of the sheet and then folding it the width of the sheet. Examine both folds and you will see that one fold is decisively cleaner and smoother than the other. The cleaner, smoother fold is parallel to the grain, and this illustrates how the paper fibers react more favorably when folded in the parallel direction.

Binding with the grain direction

Binding with the grain direction is very important for all methods of binding. Whether you’re doing a simple saddle stitch or a more complex perfect binding, binding parallel to the grain is vital. The reason that grain direction is so important to successful binding is different from when you fold and score; it is not a matter of breaking fibers. It is a matter of how paper fibers expand and contract in the open air. While this is a much less understood concept in our industry, it is an extremely important one to understand in order to avoid disastrous binding episodes.

Here’s the scoop. Paper fibers constantly expand and contract, mainly due to ambient conditions as well as glues and moisture associated with many binding processes. You most likely won’t see or notice the expansion and contraction of unbound paper, but you can be sure it is happening. Paper fibers expand and contract as much as 400% more across the grain direction of the paper fiber than with the grain direction. This means if you bind paper into the spine, across its grain direction, then as the paper expands and contracts, you will get as much as 400% more movement of the paper, fighting against the anchor of your binding. This can result in very unpleasant consequences, including gusseting of the spine of your finished piece. Gusseting is the extreme warping of the spine due to the expansion and/or contraction of the paper which is bound. There is almost no way to repair a gusseted book once it is bound, but you can avoid this issue by using proper binding techniques.

To give yourself a visual illustration of what happens in gusseting, make the “time-out” sign with your hands. You know, finger tips of the right hand into the palm of the left hand. The finger tips going into your palm represent paper fibers bound perpendicular to the spine of our book, which is represented by your palm. Now spread your right-hand fingers, representing the paper fibers expanding, and you will see them moving across your palm as the spine stays stable. What results in this scenario with paper is severe warping of the sheets as they try to move within the bound spine. You would be amazed at the strength paper has to pull a spine into funky shapes with just the small expansion and contraction movements of cross direction paper fibers.

How to determine the grain direction

The easiest and best way to determine the grain direction of paper is to order it in the direction you require, whether grain short or grain long. Grain direction is noted on most paper packaging, swatch books and paper mill stock sheets in one of a few different formats. Most commonly, you will see grain direction noted as the last dimension of the sheet. As an example, 11” x 17” would be grain long (fibers run in the 17” direction), 17” x 11” would be grain short (fibers run in the 11” direction). Sometimes the grain direction is bold, 11 x 17 would be grain long or 11 x 17 would be grain short. You may see the grain direction underlined, 11 x 17 would be grain long, or 11 x 17 would be grain short. Often on the label of a ream of paper, you will get multiple indications of the grain direction. For example, you may see – “11 x 17 grain long.” Whichever format is used, paper mills make a big effort to indicate the grain direction of every sheet of paper. If you look, you will see it.

There are few things worse than experiencing an avoidable problem. By paying attention to grain direction, you can be sure to avoid some of the all too common production errors that occur time and again due to incorrectly formatting projects with respect to paper’s grain direction.