Yes, just like wood, paper has a grain. The grain in paper comes from how the fibers of the paper are arranged. The fibers are typically parallel to each other across the sheet and knowing the grain direction is important when we go to fold the sheet of paper.
If we fold against the grain, then the fibers crack and we get an uneven or rough fold and the fold won’t be as clean or flat as we might want. Going parallel to the grain reduces the cracking and we get a smooth, flat fold.
How to determine the grain
With thinner papers it is harder to tell the grain direction, heavier papers are more obvious and easier to determine.
Three quick tests to check for grain direction
1) Tear Test – Take a sheet of paper and tear it horizontally and then vertically. One tear should have been straighter than the other. The tear that was straighter is parallel to the grain, the jagged tear is going across the grain.
2) Bend Test – Take a sheet of paper, bend the paper (don’t fold or crease it) horizontally and vertically. There will be less resistance in one direction than the other. The bend with less resistance is parallel to the grain.
3) Fingernail Test – Take a sheet of paper and using the fingernails of your thumb and middle finger pinch the paper and slide them across and then down the paper. One direction should produce a “wave”, the wave indicates that you went across the grain.
Short Grain – The grain runs parallel to the short edge of the paper.
Long Grain – The grain runs parallel to the long edge of the paper.
A quick way to tell the grain direction is by reading the package the paper came in. The second number in the paper’s dimension indicates the grain. So if we have an 11×17 sheet of paper, the grain is running parallel to the 17-inch edge of the sheet and is referred to as Long Grain. If the paper is 17×11, then the grain is running parallel to the 11-inch edge of the paper and is referred to as Short Grain.
Folding and Grain
You should always plan your folds to go with the grain of the paper. This is something our Job Planners do each time you submit a job. They figure out how to engineer your job and then they know which grain direction to order.
Sometimes you can have two folds, one that goes with the grain and one that goes across. We can minimize the problems of going across the grain by using a letterpress score. What we recommend is creating a die to score the cross grain folds. This literally bends the fibers of the paper in the direction we want to fold the paper and reduces the cracking we might get with a convention score and fold.
If you have question about how the grain in the paper might affect your next project, contact one of our salespeople. They will be more than happy to answer your questions.