All patterns have an arrow marked on them to show how to place it on the grainline of the fabric. This arrow is the Pattern Grainline and needs to be align with the lengthwise grain of the fabric.
This means that the arrows of the Pattern Grainline always run parallel to the selvedge edge.
If there are arrows at each end of the line, this means that it can be placed in either direction on the fabric. If there is only one arrow, this means that the pattern is placed in one direction only (for fabrics with naps).
For all examples the pattern grainline is marked in pink for emphasis.
The pattern grainlines are parallel to the Center Front and Center Back seams, which is the most common way for the pattern grainline to be placed on skirts. See the next image for how this is placed on the fabric.
The pattern pieces are placed on the fabric with the Pattern Grainline parallel to the selvedges of the fabric.
In this next example, the same pattern piece has the Pattern Grainline placed three different ways.
The first one has the Pattern Grainline placed parallel to the Center Front of the garment, the second has the Pattern Grainline running at right angles to the Center Front, and the third has the Pattern Grainline running at 45 degrees to the Center Front line.
Below find explanations of the effect of the Pattern Grainline on the three different pattern pieces.
This way the pattern grainline was marked on this pattern piece means that the lengthwise grain (or the straight grain), which is the strongest grain with the least stretch, runs down the Center Front of the top. This is the most usual way for the pattern grainline to be placed on pattern pieces. The crosswise grain, which generally has more stretch, runs across the bust.
The way the pattern grainline was marked on this pattern piece means that the lengthwise grain (or straight grain), runs around the bust. It is not common for the pattern grainline to be marked on a top like this. The effect it has is that there is more stretch going up/down than there is going around the body. What is more common, especially in stripey fabric, is for part of the top such as the yoke to be marked this way, and main part of the top to have the pattern grainline parallel to the Center Front. See the next image for an example of this.
The top part of the bodice (the yoke) has a different pattern grainline to the main bodice piece.
The way the pattern grainline was marked on this pattern piece means that the fabric has been cut on the bias.
Certain fabrics work best cut on the bias, and gives a different drape to the garment. Cutting on the bias can cause confusion when it is marked cut on fold. See the next example.