What are Bias Edges?
Bias edges are fabric edges cut diagonally across the lengthwise and crosswise grain (usually at 45 degrees), rather than parallel to the grain lines. The diagram below shows the three basic grain lines:
The grainline of fabric refers to the direction of the warp and weft threads used in weaving the fabric. There are three grainlines - Straight or lengthwise grain (WARP), cross grain (WEFT) and bias grain as described below.
- Straight or Lengthwise grain runs the direction of the warp threads which run parallel to the selvages. When we cut fabric parallel to the selvage edge, we are cutting on the straight grain. Fabric cut on the straight grain has the least amount of stretching, nearly no stretch at all.
- Cross grain is the direction of the weft threads that run perpendicular to the selvages. When we cut along the width of fabric (perpendicular to the selvage edge), we are cutting on the cross grain. Cross grain has the next amount of stretch, much more than the straight grain.
- Bias grain is when fabric is cut at a 45 degree angle from the straight grain. Bias grain has the most amount of stretch. This is why we need to take extra care when working with triangles or fabric cut on the diagonal. Bias grain is often used when stretch is needed, such as when you need binding for a round or curved shape.
In quilting, we encounter triangles in many quilt block components; half square triangles, quarter square triangles and flying geese to name a few. Below is one of my completed Windmill quilt blocks - notice all those triangles!
Why Does it Matter?
Why are bias edges even an issue? It matters because of the stretch that easily occurs when fabric is cut on the diagonal. Every quilter knows accuracy is paramount in quilt piecing. If we don't take extra care and employ a few simple "tricks of the quilting trade" when working with bias edges, our accuracy suffers, our blocks will not square up and our seams will not match. So, let's take a look at how we can alleviate much of the stretching issues when working with bias edges.
Fabric Matters
As a designer for Island Batik/Lumin Fabrics, I work with batik fabric a lot. I have found that batik fabric stretches much less than non-batik fabric. This is true of both crosswise grain and bias edges. In general, you will experience much less stretching when working with batik fabric. That's not to say you can't greatly reduce the stretching of non-batik fabric, you can, it just takes a little more effort.
Starching
Starch is your best friend! Absolutely, positively, without a doubt, you need to be using a starch based product such as those shown below whenever you are working with bias edges.
How to Use Starch
My favorite starch product is Mary Ellen's Best Press. I prefer it to regular starch or sizing, although I have all three in my arsenal. I use Best Press on my fabric BEFORE I cut it, or before I run it through the Accuquilt. Starch makes my cuts more straight and accurate with less distortion and it reduces fraying.
To apply starch, spray the right side of the fabric evenly and press with a medium-hot iron, NOT steam. You want to keep steam/water away from the fabric until after its pieced or quilted. If I am working with non batik fabric I will use starch on both sides of the fabric.
In addition to starching before the fabric is cut, I also starch during the piecing process (usually at several intervals while making a block) and definitely after the block is done. Always remember to PRESS not IRON when quilt piecing. More on that in the next section.
Pressing vs Ironing
To the layman, the words pressing and ironing are used interchangeably. They are not the same however, and the difference between them can make a world of difference in the accuracy of our piecing.
Ironing is what our mothers did to our father's cotton shirts. It's the process of moving the hot iron back and forth across the fabric to smooth out the wrinkles. Pressing is when you raise and lower the iron as you move from spot to spot. There is no sideways motion in pressing. A hot iron can easily distort fabric and that's a no-no when piecing quilt tops. Always press, never iron your piecing. The only time I iron quilting fabric is BEFORE it is cut.
Bias on the Bottom
If one of your fabric pieces is bias cut and one isn't, always sew with the bias piece on the bottom, against the feed dogs. This will help reduce stretching and distortion. This "trick" can also be used when one fabric piece is cut on the straight grain and the other is on the cross grain, put the cross grain fabric on the bottom.
Be Gentle in all Things
When working with bias edges, keep in mind that even a small amount of stretching can cause major problems down the road for your quilt piecing. Be gentle in everything you do while working with these delicate edges. Pay attention to how you store your cut pieces, how you pick up and carry them, how you pin them, etc.
Conclusion
In time, working with bias edges (and being aware of the grain of fabric) becomes second nature to a quilter. Each quilt lets us expand our skills and teaches us new things, adding "tricks of the quilting trade" to our arsenal. I hope this tutorial has done that for you!
Until next time, happy quilting!
