Paper grain direction: what it is and why it matters

During papermaking, cellulose fibres line up in the direction the paper machine runs. This is called the paper’s grain direction. Although you cannot see it, grain directly affects the result of printing, folding and binding.

Long grain and short grain

If the fibres run parallel to the long side of the sheet, it is long grain; if they run parallel to the short side, it is short grain. Catalogues usually show this next to the size, for example 70×100 cm (LG), or by underlining the dimension that runs with the grain.

How to check grain direction

• Bend test – gently bend the sheet both ways. It bends more easily along the grain.
• Tear test – paper tears straight with the grain and ragged against it.
• Moisture test – wet one side of a small piece; it curls around an axis parallel to the grain.
• Fingernail test – pull the edge between two fingernails; the edge across the grain ripples more.

Why it matters

Folding

Paper folded with the grain gives a smooth, clean fold. Folded against the grain, especially heavy or heavily printed stock, it cracks along the fold and the ink breaks.

Books and notebooks

In binding, the grain should run parallel to the spine. Otherwise pages are stiff to turn, wave, and the book tends to snap shut.

Moisture and dimensional change

When paper absorbs moisture, it expands much more across the grain. This can cause misregistration in offset printing and warping of boxes and covers.

Packaging and boxes

A box’s stiffness also depends on grain. Correctly oriented board makes the box walls stronger.

Practical tips

• Always ask about grain direction when ordering paper.
• When cutting, lay out pieces so the fold line runs with the grain.
• If you must fold against the grain, score first.
• Let paper acclimatise in the print room for a few hours before printing.

Printshop offers designer papers, board, lamination film, foil and binding materials. For details and prices, call or message us on WhatsApp: 050 890 11 44. Address: A.Salamzade street, Baku.