Grain Direction. Why is it important?
How to pick the right grain
direction?
Paper Grain is the direction of fibres in a sheet or web of paper, generated during paper making process.
When paper is cut into sheets, it will be either long-grain (if the fibres are aligned parallel to the sheet's longer
dimension) or short-grain (if the fibres are aligned parallel to the sheet's shorter dimension). The direction of
the majority fibres is called "Parallel to Grain" or "With Grain". The other direction is called "Perpendicular to
Grain" or "Across Grain".
Think of paper fibres as tooth-picks that are lined up. The direction the toothpicks point is the grain
direction. You can understand now that the stiffness will be higher from top to bottom in this image, and
the folding will be easier when done parallel to this direction.
Paper will tear and fold more easily with the grain and with greater difficulty across the grain. It has more
strength/stiffness across the grain direction. Especially in thicker papers, it can crack when folding against the
grain. Finally, when paper gains or loses moisture, it expands or contracts much more across the grain (think
of it as each toothpick getting thinner or fatter!). This expansion / contraction can also cause it to curl.
Characteristic: Folding
With Grain: Easier
Against Grain: Tougher, Cracking
Characteristic: Stiffness
With Grain: Less
Against Grain: More
Characteristic: Expansion
With Grain: More
Against Grain: Less
Characteristic: Curling
With Grain: More
Against Grain: Less
How to tell the grain direction of a paper?
There are a few tricks to find out the grain of a sheet of paper. It is easier to tell with thicker papers and less so
with thinner papers.
1. 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 with grain than against the grain.
2. Tear Test – Take a sheet of paper and tear it horizontally and then vertically. The tear that was straighter is
parallel to the grain, the more jagged tear is across the grain.
3. Wet Test – cut a small square (around 2 x 2cm) and dip the paper into a glass of water. In a few seconds, the
paper should curl. The edge that curls is across the grain and the edge that is straight is parallel to the grain.
Know which grain direction to use!
Cartons: Usually the grain direction is kept horizontal (assuming the opening flaps are on the top and
bottom). This is because cartons are usually held by the sides, and stiffness in that direction is required
functionally.
Books: Usually the grain direction is kept parallel to the binding edge. The two main reasons are: When
turning pages, there is less stiffness perpendicular to the binding edge, due to which the pages tend to fall to
the left or right, rather than stick up. Secondly, paper expands or contracts if it picks up or loses moisture –
having the grain parallel to the spine ensures this change of dimension is not at the spine, where it is fighting
with the adhesive which is trying to prevent it from moving.
Folders: Usually the grain is kept parallel to the folding direction – this minimises cracking at the folds.
Labels: With self-adhesive labels, the direction of the label on the reel is determined more by the applicator
machine used for dispensing the labels. Do find out the requirement of your applicator. If pasting the labels
manually (as is usually done for smaller lots), it shouldn’t matter much.
With wet labels, it should be parallel to the direction of the turn of bottle/product during application – this is
so that there are less problems during application. However, there are different types of applicators, so it
would be best if you find out from the people running the applicator and inform us of the requirement.
Grain Direction Marking
Paper manufactured by major producers usually has a long grain, that is to say, parallel to the long side of the
sheet. Handmade paper and some other sorts and brands of paper may have short grain (grain parallel to the
short side). Sometimes grain direction may be much less noticeable or even almost undefined.
Markings on the production packaging should help you finding the grain direction.
There are several standard ways to mark the direction:
With words Grain Long or Grain Short.
Underscoring one of the dimensions: 10×15 means short grain, 21×7 indicates long grain.
Sometimes machine direction may be marked like this: 33,1M×46,8, which indicates short grain.
One more way to mark the grain direction is by ordering the dimensions. The last one gives you the
dimension: for the 10×15 the grain is long, and 15×10 sheet has a short grain. That’s sort of an industry
standard. Unfortunately, in case of long grain you would never know if the manufacturer forgot to mark the
grain or decided to use that standard way of marking.
If there are no markings, you have to check the grain direction by experiment before proceeding to any
further steps.
Wrong Grain Direction
It is very important to know the grain direction because paper and cardboard stretches and bends
differently along and against the grain. In wet conditions (including glue application) paper products tend to
wave (with curls going along the grain).
Wrong grain direction is often chosen for large print projects. Cutting a sheet of paper in the ‘wrong’ direction
may save you up to 10% of paper or even more. However, wrong grain direction makes book less usable and
even leads to structural damage and early deterioration:
When you turn the pages, they tend to bend a bit. If you have wrong paper grain direction, there is a higher
chance of fractures or tears. Pages may also resist turning if the grain direction is wrong.
In wet conditions wrong grain direction may result in damaging the spine and braking the book structure. That
can happen even during gluing or pasting the book.
Glue may penetrate along the grain direction from the spine inside the book block.
Book may not open properly if it is bound with wrong grain direction.
Pages may curl and flare, edges may become wavy.
Cross-grain layouts may also lead to problems (e.g. covers have grain direction that is different to grain
direction of paper).
Folding paper with wrong grain direction (not going along the grain) may result in cracks and other damage to
paper.
Grain direction should go along the spine. That remains the same for all the different elements of the book:
pages (sheets), spine lining, endleaves, covers, and any other paper and cardboard materials you use. You
should also mind the grain direction during other processes, like box-making.
How to Find Paper Grain Direction?
I will list five different ways to determine grain direction even while I prefer binding paper and cardboard to
other methods:
Paper and cardboard offer noticeably more resistance in one direction than the other. That resistance comes
from grain springing. Grain direction goes along the curve of least resistance. Method works well for thicker
papers and cardboard, however you can try to apply it to a thinner paper.
Applying moisture to a side of paper, you will make it wave or curl. If the whole moistened side starts to curl
upwards or downwards, that means grain goes along that side. If the side becomes wavy, grain follows
perpendicular direction.
When you tear the paper against the grain, fibers do not allow the tear to go straight. Instead, you get a sort
of zigzagged tear. Paper and cardboard also tend to flake when torn against the grain. Tearing along the grain
gives you almost a straight tear.
When folding along the grain, you’ll get an almost smooth fold. Folding against the grain may result in cracks
and even tears (depending on paper). That happens because fibers are aligned perpendicular to the fold and
you break them folding the sheet.
Sometimes you can identify grain direction by the pattern of the material you use. That happens with some
sorts of cardboard and Japanese paper.
Obviously, the last two methods make an irreversible damage to your material; therefore, they couldn’t be
used if you have only so much paper or cardboard. For almost all my projects I prefer bending paper and
cardboard.
That said, I’ll illustrate what happens with grain direction when you fold A4 (210 by 297 millimeters / 8.27 in
× 11.7 in) and A3 (twice as large as A4) sheets. I suppose that A4 and A3 sheets usually have a long grain.
Out of a standard A4 piece of paper you may bind a book with page size similar to A6 (quarter of A4). But A5-
sized (half of A4) quires would have a wrong grain direction.
To bind a book with dimensions similar to A5 you have to take A3 paper and fold it two times in quarter. Than
the grain direction would be long once again.
