Updated: Oct 20
I often answer questions for new quilters that are some variation of “I followed all the instructions, but my blocks still turn out a little wonky.” (Yep, mine too ... but I digress!) There are many reasons that blocks can go a little awry. One of those is misusing the fabric grain.
What is fabric grain? It doesn't have anything to do with gluten and won't add to your net carbs. Grain is the term that describes how the various threads are arranged in a piece of fabric.
Warp threads: These are the long threads that are stretched on the loom and secured. They run the entire length of the woven fabric. They make up the fabric’s lengthwise (or straight) grain.
Weft threads: These threads are woven back and forth across the width of the fabric. They make up the crosswise (or cross) grain.
Selvage: At the edges of the width of the fabric, there is a tightly woven strip on each side called selvage (or selvedge, depending on what part of the world you spell in). The selvage often has the manufacturer, studio, line name, and/or designer printed on it, and sometimes also includes print ink color and registration marks. Generally, quilters trim off selvages and avoid them entirely, but sometimes quilters incorporate the printed selvages into their block designs, and that is a fun way to record your fabric journey.
Bias: A true bias is a cut made at 45 degrees to either the straight or cross grain of the fabric, but for quilters, any angle of cut that isn’t on the grain is referred to as a bias cut.
How does the grain affect my quilt?
Fabric pieces cut on different grains stretch differently. Stretch affects patch/block shape and alignment.
Fabric cut on the lengthwise/straight grain–parallel to the selvedge–has the least stretch because the long threads are secured tightly on the loom and are often stabilized with a glue that's washed out prior to shipping. They have a very strong, well-structured arrangement.
Fabric cut on the crosswise grain has a little more stretch because these threads were moving as the shuttle passed back and forth when the fabric was woven, and they're not quite as tight. It still has much less stretch than fabric cut on the bias.
Fabric bias has neither warp nor weft threads to stabilize it, so it can and does stretch quite a lot. Fabric cut on the bias has an edge that can easily stretch during handling and pressing.
Paying attention to fabric grain when cutting your fabric can definitely help in the accuracy of your block piecing and, consequently, your quilt top assembly. For example, if you plan to include long border strips, you will have less wavy fabric and fewer border ruffles if you cut these pieces on the lengthwise/straight grain. Sashing strips that are cut on the straight grain can help to stabilize the edges of your blocks, which can be particularly handy when you have blocks with bias-cut edges, such as half-square triangles. When cutting pieces for blocks, ensuring that you’re cutting as close to the grain as possible can help to minimize stretch at your block edges and minimize fraying.
So … bias is bad?
Not always. While bias edges should be handled carefully to minimize warping your block, they show up a lot in quilting and aren’t anything to be afraid of. In fact, sometimes the stretch inherent in bias-cut fabric can be quite useful:
When piecing, such as when manipulating fabric for curves;
When turning an applique edge, a bias cut edge will turn under very cleanly;
When fussy cutting a particular part of your fabric print, you may make bias cut(s);
When binding your quilt, you may wish to use bias-cut fabric to curve gently around the edges of your quilt.
If your quilt pattern has bias edges on blocks, be aware and handle them gently. The less you stretch your block edges, the more likely it is that your blocks will line up perfectly during quilt assembly. If you are making half-square triangles, some HST methods create more bias edges than others. Check out our free HST Guide for more info.
Pro tip: If your quilt top has bias edges on the outer edge of the quilt top, you can help to stabilize it by stitching a “stay stitch” line around the entire perimeter of the quilt about ⅛” from the fabric edge. Essentially, your stay stitch gives the quilt edge a grain line anchor to help reduce the stretch.
I’m paper piecing my quilt. The fabric grain is all over the place! Is that bad?
Not at all. When paper piecing, the manner in which the patches all build upon one another as they are added creates stability along the way, and you have very little opportunity to warp the block during construction. When your block is complete, handle it carefully if it has bias cut edges, as you would with any other block, especially if you have used the freezer paper piecing technique and your papers are no longer on your block. Many through-the-paper piecers leave their papers on until the last moment to help keep the block shape exactly as intended.
What about ripping fabric?
Your local chain store fabric shop probably cuts your fabric with scissors. It’s fast and results in a pretty edge, but it’s not likely to get a cut that’s right on the grain. One way to get the fabric to separate close to the grain is by ripping it. Yes, that’s right. Cut a small starter cut (either along the lengthwise grain or through the selvage) and then simply pull the fabric apart with firm, sharp tugs. It will look a little wavy along the torn edge at first, but that presses right out, and it’s a terrific way to get nice long straight grain pieces, especially for borders. It’s only a little traumatic the first time you hear fabric tear. After that, it’s oddly satisfying! Give it a try sometime and see what you think.
As always, drop any questions in the comments, and … happy quilting!