How can you determine the grain direction of paper or cardboard?

As explained in our previous post, the grain direction of paper and board is determined by the manufacturing process. The fact is that the paper fibres align themselves primarily in the grain direction of the paper or board machine, i.e. along the direction of movement of the machine’s wire.

If you tear a paper or board sample with and against the machine direction, the tear will always be smoother when made with the machine direction than against it.

This means, for example, that for a sheet of A4 paper with a machine direction of 210 x 297 mm (long grain), the long 297 mm side runs parallel to the machine direction of the wire, and the fibres are therefore essentially aligned in this direction. (see arrow)

If you now tear along the short, 210 mm side, the paper tears along the grain, resulting in a smooth tear. If, on the other hand, you tear along the long, 297 mm side, an uneven tear results, as you are tearing against the grain.