Paper Grain Direction: Short Grain vs Long Grain
March 31 2021
Do you remember the first time you heard about grain direction? For me it was a real “eh what” moment. But it’s not actually that difficult a concept to get your head around once someone explains it to you.
When paper is made, the fibres in the pulp spread in the direction the machine runs. This creates a grain direction. The sheet can then be cut long or short.
A short grain is when the grain runs across the short end of the sheet. A long grain is when the grain runs across the long end of the sheet.
For example, on a 720mm x 1020mm (B1) sheet of paper, if the sheet is cut “grain short”, the fibres will run across the 720mm side and vice versa.
Why is this important? Because the grain of the paper determines how the paper reacts to mechanical actions like folding, scoring and binding. Knowing the differences will ensure you use the right kind of paper in your project.
How does paper grain affect a finished print project
The decision to print in the long or short grain direction is often based on format size, which determines the least amount of waste from the cut-off.
Grain direction determines how paper reacts when it is folded, scored and bound. In practically every application, it is more desirable to go with the grain.
When paper is folded with the grain, the fold is smoother. When paper is folded against the grain, the fold is visibly less appealing.
In fact, going against the grain is considered an amateur mistake in printing. Paper should always be folded parallel to the grain’s direction.
If you fold against the grain, you always need to score the paper first. Scoring prepares the paper for a fold that is against the grain.
When binding, the paper grain needs to be parallel to the book binding edge. The grain direction also needs to be consistent in its direction, otherwise pages may resist turning or stick out from the book when closed.
The heavier a paper, the more important it is to get grain direction right. Heavier paper shows imperfections more than lighter paper. It is also more difficult to work. This is true of copier printing where thick papers are common.
How to detect the grain direction
You can detect grain direction in textured paper by feel. Take a sheet of paper, put it on a smooth surface and gently run your finger across it in both directions. Which is smoothest? The smooth side is the side that’s cut with the grain.
If the paper is heavy, you can also tell if paper is cut with a long or short grain by observing the fibres: with long grain, the fibres will run parallel to the sheet’s long dimension. For example, on an A4 sheet, the fibres will run vertically down the paper.
Another way to tell is with a tear test. Paper will tear a lot easier with the grain. If you have spare paper, try tearing it. The easier tear direction is the grain direction.
Aside from these field tests, the best way to determine paper grain direction is to order paper in the direction you require.
If you are unsure about grain direction after receiving your paper order, the last dimension on the packaging often denotes grain direction.
For example, 720mm x 1020mm paper would be 1020mm long and 1020mm x 720mm paper would be 720mm short.
Wigston makes it easier by sticking a long/short label on the packaging. A bold number like 720mm x 1020mm would also signify the grain direction.
So there you have it. A quick introduction to paper grain direction. You’ll never look at a sheet of paper like you did before!