One of those things that experienced quilters assume newer quilters know is what fabric grain is. We often forget that someone, once, had to tell us about it. Some of us may know about the general concept, but not exactly what it is, or, why it matters.
Fabric grain refers to the direction that the threads in the fabric are going. Fabric has been made in the same general manner for a very long time. The basics haven’t changed much. You still have a loom with threads stretched from the bottom to the top and you still have a shuttle that sends threads perpendicular to the original threads. Warp threads are those that stretch from the bottom to the top, which ends up being the length of fabric. Weft threads are those that cross the grain, or go side to side. This is referred to as width of fabric. The very edges where the weft thread doubles back to make the next row is called selvage.
Length of fabric (LOF/Warp) threads are very stable and tend to not have very much ‘give’ or stretch to them. Width of fabric (WOF/Weft) threads have a bit more give. True bias is how we refer to the direction that is a 45° angle to the length or width of fabric. When quilting a bias edge is anything that isn’t parallel to the length or width, no matter the actual angle.
In this picture I am exerting a fair bit of force pulling on the length of fabric. You can’t really see much deformity in the edges.
For my width of fabric picture, I tried to pull with the same force as the first picture. You can see that there is a bit of deformity to the fabric, but still not much.
In this picture I’m not putting much force behind the stretch. Bias grain is very, very stretchy. Even on a cotton fabric.
Now, why should we care about all of this, other than it’s a fun fact to know and share? The grain of your fabric and how it is cut will affect how accurate and easy your piecing is. An edge that has a 90° angle with the threads will not stretch much, but a bias edge will be much more difficult to keep stable and unstretched. There are a lot of fun and easy patterns (particularly being shared around on Pinterest) that utilize the technique of sewing fabrics in squares, then cutting them into triangles, and reassembling back into squares. It’s absolutely awesome that there are free patterns and tutorials out there. It makes learning easy. The downside is that in the effort of making the tutorial short and concise the author (or video producer) often leaves out the little things that we assume all quilters know. This leads back to the above. Experienced quilters know these things, but if you’re new and you’ve never been told those little things… Well, you can’t know.
I’ve found a really cute little tutorial on Pinterest by TeresaDownUnder. You can find her post and the associated video here. It’s a well done, concise video on strip piecing and rearranging. She shows at the end of the video how you can combine these new triangles into a very large number of combinations that look really cool.
Let’s talk about the potential difficulties you could have with this sort of thing (and how to help prevent them).
You can see that the outside edge of the block is all bias edges. Remember, these are all very stretchy. When we press, these are very easy to distort and pull out of shape (particularly those tiny little pieces).
I’ve sewn a block together (I was quite lazy and used the same fabric) after cutting it apart on the diagonal, like TeresaDownUnder shows.Without pressing it, you can see that the edges are fairly nice and square. (Remember, those outside edges are bias now).
After aggressively pressing none of my edges are straight. I won’t be able to sew a straight, accurate 1/4″ seam along any of it. (Side note: This is a good example of how little your thread color matters when piecing. I used black thread and the only place you can see it is on the edges that will be hidden). I talked about how important sewing an accurate 1/4″ seam and a straight seam is in previous posts. If your seam isn’t straight or isn’t accurate at 1/4″ it makes your quilting much less exact and much more likely to have problems in the end (like ruffles or tucks when quilting).
How can we prevent the bias edges from stretching? Some of that is unavoidable purely because they are bias and are very likely to stretch. We can employ good pressing techniques and not scrub at our fabric (think your grandmother ironing a shirt). I promise to do a post on good pressing technique later, but the short of it is pick your iron up and set it down without moving it while it is touching the fabric. This will help prevent the threads in the fabric from warping because there won’t be any force acting on them, causing them to move.
While this works when pressing, the edge is still very likely to stretch when sewing because of the drag from the machine bed and our fingers guiding the fabric. A starch or starch alternative like Mary Ellen’s Best Press is a great way to help. A light spritz of your chosen stabilizer and a little heat from the iron (carefully picked up and set down) will go a long way to helping keep those edges stable.