All About the Grain Line of Fabric

In weaving fabric, manufacturers place the lengthwise threads (warp) tightly in the loom to eliminate stretch. The crosswise threads (weft) are then woven into the lengthwise threads, but are not stretched as tightly, leaving a little "give" in the finished fabric. Fabric pieces cut diagonally across the grain line (on the bias), are susceptible to stretching because there are no stabilizing threads along the edges.

• The crosswise grain runs perpendicular to the selvage. It is sometimes referred to as the cross grain. The crosswise grain is usually looser and has slightly more stretch than the lengthwise grain.
• True bias intersects the lengthwise grain and crosswise grain at a 45˚ angle, but any line that runs diagonally between the two grain lines is called the bias. It has more stretch and flexibility than either the crosswise or lengthwise grain.
• When the lengthwise grain and the crosswise grain intersect at a perfect right angle, the fabric is said to be on grain, or grain perfect. If the grains don't intersect at a perfect right angle, they are considered off grain and the threads are distorted.

• A fabric that is slightly off grain is still usable. However, significantly off-grain fabric will require careful handling during assembly and heavy quilting to stabilize it in a finished quilt.
• If the design motif can only be cut on the bias, backing it with a lightweight fusible web can help to stabilize it.
• Unless it is for decorative purposes, do not use the selvage edge (the tightly woven finished edge) in a quilt. When washed, the selvage, because it is so tightly woven, may shrink more than the rest of the fabric.
• The arrow on a pattern piece or template often indicates which direction the fabric grain should run. Because one or more straight sides of every fabric piece should follow the lengthwise or crosswise grain, it is important that the line on the pattern or template runs parallel to the grain.