Get Familiar with FabricGrain

By Janet Wickell, About.com Guide

About Fabric Grain

The term fabric grain refers to the way threads are arranged in a piece of fabric. Grain is one of those quilting topics that you might not think is important, but the way you cut your quilting patches in relation to the grain can produce quilt blocks that are accurate and easy to assemble--or blocks that just won't do what you want them to do.

Let's take a look at grain components.

Warp Threads

Long threads, called warp threads, are stretched on the loom and secured. They become the fabric's lengthwise grain, the threads that are continuous along the length of your yardage as it comes off the bolt.

Weft Threads

More threads, called weft threads, are woven back and forth, perpendicular to the warp threads and along their entire length. These weft threads make up the fabric's crosswise grain.

Straight Grain

The lengthwise grain and crosswise grain are both regarded as straight grain, sometimes called straight-of-grain.

Selvages

Selvages are the bound edges that run along the outermost lengthwise grain. They are formed when the weft threads turn to change direction as the weaving process travels down the warp.

Fabrics are very tightly woven for a half-inch or so from the selvages inward, keeping the edges stable while fabric is on the bolt.

Fabric Bias

True bias is defined as the direction at a 45-degree angle to the straight grains, but in quilting we refer to any cut that doesn't run along a straight grain as a bias cut.

Advantages of Straight Grain FabricCuts

Straight Grain Cuts Are Often Best

Straight grain patches, fabric pieces with edges cut parallel to either straight grain, are less likely to stretch out of shape than pieces with edges cut along the bias, because the interwoven threads give their cut edges extra support.

Cuts along the lengthwise grain are less stretchy than crosswise grain cuts:

  • Unlike the moving weft threads, the warp threads were firmly attached to the loom during the weaving process, holding them in place and enhancing their structure.
  • The interlaced weft threads help stabilize the warp threads.
  • There are usually more warp threads per square inch than there are weft threads. The extra density adds strength.

When to Use Straight Grain Cuts

  • Fabric squares and rectangles are nearly always cut with their edges along the straight grains to minimize stretch during sewing and handling.
  • Because they do not stretch easily, long strips cut on the lengthwise grain make good quilt borders and sashing. They can stabilize and help you square-up the outer edges of blocks or quilt tops.
  • Sashing strips with long edges along the lengthwise grain add stability to blocks.

Using Bias Cuts in YourQuilts

There are no threads to stabilize fabric along the bias, so cuts with their edges along the bias are quite stretchy. The stretch can work for you or against you:

Helpful Bias Edges

  • Long, stretchy strips cut along the bias are easy to apply as binding to a quilt with curved edges.
  • Thin tubes made from bias cut strips can be shaped to form stems and other delicate shapes for applique.
  • Bias cuts can be turned under easier for some curved and slanted applique shapes, like hearts.

Problem Bias Edges

  • Bias edges placed along the outer edges of quilt blocks or other components can stretch out of shape as you handle the quilt during construction, making it difficult to match and sew pieces together accurately.
  • Triangles always have at least one bias edge. Analyze the pattern to determine the best placement for it--usually on a block's interior and sewn to a straight grain piece when possible for stabilization.

There will be times when you decide to cut a patch with bias edges in the "wrong" position in order to use a specific part of a print or to make it flow with its neighbors. Occasional wayward patches are fine--just pay attention to where the stretchy bias edges are and handle them with care.

An Easy Stretch Test Illustrates FabricGrain

You can see the difference in stretch when a square of fabric is stretched along the lengthwise grain, the crosswise grain and the bias.

Fabric Grain Stretch Test

  1. Cut a small square of cotton fabric with edges parallel to the straight grains.
  2. Tug on the fabric side to side, along one straight grain, then tug from the other direction. Do you feel and see a difference? Did you notice slightly less stretch in one direction? That was the lengthwise grain.
  3. Now tug on the square from corner to corner--along the bias. It probably stretched quite a bit, and if you tugged too hard it may have become permanently distorted.

Becoming accustomed to stretch differences helps you identify lengthwise and crosswise grain in scrap patches with no selvages, like those small squares quilters love to swap!

Experiment with fabric grain. It won't take long until you understand the best ways to place grain in your quilts in order to achieve the results you're looking for.