Grain lines indicate thread direction in fabrics. There are two different grain lines: crosswise grain and lengthwise grain. Cutting fabric diagonally creates a bias edge. This article explains what grain lines are and how quilters use them to make quilts lie flat.
Glossary Terms for Grain Lines
- bias cut
- crosswise cut
- crosswise grain
- lengthwise cut
- lengthwise grain
First we need to understand how threads are woven into fabric. Refer to the diagram below.
- Each warp thread is a continuous thread running the length of the fabric. Warp threads are parallel to the selvage edge. This creates the lengthwise grain.
- The weft threads are woven through the warp threads from side to side. This creates the crosswise grain.
The warp threads are tight and impossible to stretch. This makes the lengthwise grain strong. Cut along the lengthwise grain to make a lengthwise cut. This cuts the weft threads, making the crosswise grain slightly weaker. The lengthwise grain remains strong.
Weft threads are woven and have a very slight stretch. This makes the crosswise grain slightly weaker than the lengthwise grain. Cut along the crosswise grain to make a crosswise cut. This cuts the warp threads. The lengthwise grain may be slightly weaker but it is still very strong.
Cut along the diagonal to create a bias cut. This cuts both warp and weft threads. Bias cuts have a large amount of stretch. Bias cuts can be useful for adding curved elements to the quilt design. One way to use bias is for making bias binding to bind curved edges. Bias can also be used to make undulating vine or leaf elements in applique.
Where you don't want bias is along the edges of fabric pieces, units, blocks and borders. The stretching caused by bias cuts can cause the edges to wave and distort. The edges will not lie flat. Bias can create wonky
Whenever possible, grain lines should follow the edges of pieces, units, blocks and borders. Here are a few guidelines:
- When cutting strips to sub-cut into smaller units, cut along the crosswise grain (selvage to selvage). This is often called Width of Fabric (WOF) cuts.
- If working with a bias edge is your only alternative, consider using spray starch or a starch alternative. Starching fabric makes it stiffer and less likely to stretch out of shape.
- When attaching borders, don't take a long piece of fabric and sew it to the sides. Always measure the quilt top first. Cut the borders to the required size and attach.
Article – Lengthwise Grain Borders and Binding
Video – Strip Piecing Basics by QuiltNotes (5:40)
Video – Understanding Fabric Grain Line by Jinny Beyer Studio (2:13)