Most readily available papers, such as those sold in stationery shops, are machine made. As the fibres in the pulp are drawn into the machine they tend to lie in the direction of travel. The paper-making machine, which is as long as a football pitch, or more, winds the completed paper into rolls. The grain of the paper runs around the roll, not across it. Any roll of paper that has an appreciable length, will have such a grain: sticky paper tape; bulk-buy brown kraft parcel paper; newsprint.
Normally such papers are made as wove, where the surface is smooth. Sometimes an extra roller (a Dandy Roll) is used at an early stage in the machine. This acts as an extra sieve, to enable water to drain away. It is made of a fine mesh of many wires, all lying along the roller. These wires are held in place by supporting wires, called chain-lines. It is the chain lines that indicate the grain direction of the paper. The more conspicuous narrow mesh from the Dandy Roll is sometimes mistaken for grain markings. It is the opposite.
The picture below has been enhanced to make the almost invisble lines show up. The chain lines run from left to right, as does the grain.
The paper has been torn, once with the grain, the other against the grain. It is easy to see that one of the tears has a tendency to veer off and take the easy course of following the grain.
