Clues and Knowhow: Office Paper: Clue No. 5: Check paper grain
In paper production the paper´s fibres orientate themselves parallel to the direction of the production. This alignment long grain has wide influence on the paper`s behaviour.
In direction of production paper will extend very little when traction forces affect it (usually: long side of the sheet). Rectangular to this direction it can extend much more (usually: short side of the sheet).
Branded goods as a rule have very little extension in the direction the paper is fed into the printer. This can be different with "no-name" products. So, if you plan to use the latter, you should check its grain before you buy a lot of it.
There are several methods how you can do that:
Tear test: Take a sheet of office paper and tear it crosswise (left picture). The fissure will not be straight, if the long grain is in machine direction.
If you tear it 90 degrees to the previous dirction, the fissure should be relativly straight, because it runs parallel to the direction of the fibres (right picture).
Droop test: Cut two strips of paper of the same size from the long and the short side of the sheet. Hold both next to each other between your fingers. One strip will droop more than the other.
The one with less droop comes from the machine direction.
Moisture test: Wet a sheet of paper and let it dry. There will be less waves in machine direction than rectangular to it.
Folding test: Fold the sheet along the long side and across it. One crease is smooth (left picture), the other shows numerous cracks right picture). The smooth fold is in machine direction.