Before 1803 all paper was made by hand. Paper is made of cellulose fibre and during the long period when paper was made by hand the source of the fibre was cotton, flax and hemp and the source of the cotton, flax and hemp was rags and old rope. During the Industrial Revolution the demand for paper grew and so did the demand for rags for paper making. Soon after the introduction of paper making machines came the use of wood pulp to reduce the demand for rags. Of course, the quality of the wood pulp paper was much lower than rag paper, especially if the acidic lignin content was high.
Handmade paper is made by suspending the fibre in a vat of water, usually with some additives, into which the vatman would dip a mould called a deckle and swish it around, from side to side then forward and back, so the water would drain, and an even coating of fibre was deposited on the wire mesh of the deckle. The coucher then turns out the layer of pulp onto a felt mat and after a pile of layers were made this was pressed and the paper dried and potentially further treated.
Johnson described the fibre as being like small ribbons and the process of bonding them together as being like felting. It’s a nice description that is easy to visualise. When the vatman swishes the deckle about side to side and back and forth the direction of the long fibres are more evenly distributed in the paper.
Grain in paper is due to the alignment of the fibres in a dominant direction. Thus, in handmade paper where the fibres are more randomly oriented there is little grain direction (There is nearly always a detectable grain in handmade paper due to more swishing in one direction than the other. But it almost always stretches in both directions). But in machine made paper the pulp is pumped onto a mesh that is continually being fed through the paper making machine. The process tends to align fibre in the direction of the movement of the mesh. In the resulting roll of paper, the grain direction will run into the roll, parallel to the side of the roll of paper. Book cloth has a grain too and it is in the same direction, parallel to the selvedge.
So why is this important? There are two important properties in regard to grain for the bookbinder. First paper folds much easier parallel to the grain. The other is that when the fibre gets wet, it swells in width and not length and thus paper will expand, often described as stretch, up to 8 times more across the grain than in the direction of the grain.
The result is one of the most universal rules in bookbinding, that the grain direction of all materials should run head to tail in a book.
But why is this rule so important?
Paper folds better along the grain. So, a book opens better if the grain is head to tail. The way paper bends out from the spine is called drape. The better the drape the flatter the book will open out. In books that have been bound with the grain the wrong way the pages often crinkle when you open them putting a lot of pressure on the spine.
Secondly as materials expand and shrink, with different materials adhered to opposite sides of boards the grain can result in a pull which warps the boards (remember, bookbinders call the covers boards). If the boards warp head to tail a lot of stress will be put on the hinges at the spine and eventually these hinges will give way and the boards will be detached from the book.
There are a lot more things to learn about grain on your bookbinding journey, but to start with you just need to follow the rule of always checking grain direction and making sure it runs head to tail, for paper, board and cloth.
How do you find the grain direction?
Try folding a piece of paper in both directions. It will fold easier in the direction of the grain. If it is not obvious with a single sheet, often it can be determined with multiple sheets of paper.
Paper tears in a nice straight line in the direction of the grain. Try tearing the paper in both directions.
Moisten the edges of a piece of paper in a corner. Because the edge of the paper across the grain will expand much more it will crinkle. The direction that doesn’t is the grain direction.
An elegant method from Johnson, which I never use, is to cut two narrow strips of paper from a corner and wet one side on each. The piece that stays standing is from the corner going with the grain.
There are other methods, which use the same properties of folding and expansion with moisture. Sometimes you can’t destroy or damage a piece of paper being tested and the gentle fold method is really the only one available.
Other things a new bookbinder will soon learn is that paper frustratingly often has the grain direction which results in it not being possible to use the papers as efficiently as possible. The next thing you learn is that printers care more about efficient use of paper than binding and will print resulting in the wrong grain direction. Finally, grain direction becomes part of the mechanics of binding so that when confronted with handmade paper a new set of challenges come up.
For more information about using the paper grain read the article Grain to Advantage.
DAS Bookbinding 