Tips for Sewing Bias Edges
A bias edge exists when we cut fabric at an angle (like for triangles), and it is very stretchy. Without care, this stretch can cause puckers in our quilt blocks. Keep reading for a few of my best practices to prevent distortion as you piece our quilts.
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Quilting cotton is woven with threads perpendicular (at right angles) to one another: the warp and the weft. A bias edge is created when we cut our fabric across these threads at an angle (like for triangles). A bias edge is very stretchy, so if we aren’t careful, it can cause warping, puckering, or pleating as we piece our blocks and quilt top.
Fabric Preparation
While I am often a bit lax about pressing my fabric before cutting, if you are going to be cutting bias edges, it is important to slow down and prepare your fabric. Press the fabric and use a spray bottle with water to steam out any wrinkles or folds. Then, spray the reverse of the fabric with starch (I prefer true starch here, not pressing spray). Spray thoroughly (but don’t over soak), allow the starch to rest and settle into the fibers for a moment, then press again. Working with bias edges is definitely the time to starch your fabric “crispy”!
If you’ll be laying your bias edges across any straight edge cuts to piece (like laying a triangle over a square for a stitch-and-flip block), I also recommend starching the fabric you’ll be using for the squares. It will make it easier to line your pieces up later without stretching them.
Cutting
It is always the best practice to move your fabric as little as possible when cutting, but that becomes even more important with bias edges. Place the ruler carefully, and avoid dragging, tugging, over-handling your fabric as you cut. If keeping the ruler steady as you cut is a challenge, you may find the SewTites Magnetic Cutting System helpful (Use code QUILTINGROCKSTAR for 10% off!)
Piecing
If you guessed that I am going to recommend pinning, you’d be right! But before that, let’s talk about positioning your fabrics. You want to lift-and-lay your pieces together. Not oochie-scoochie and tug on them. Every tug and pull can stretch that bias edge, so be very, very careful. Then, pin the pieces together. I pin my fabrics with the pin perpendicular to my sewing line so it’s easy to grab my pins out with my right hand as I sew.
Pressing
As with long strips, truly pressing, not ironing, is key. Fabric becomes more pliable when heated. It is what allows ups to press seams flat, but it can also contribute to warping. The debate around pressing versus ironing is probably as old as quilting itself, and this is a situation where avoiding drag on the fabric is quite important. Lift the iron and set it down the fabric rather than dragging it down the seam or pushing across the seam and distorting the fibers.
I like to “set” the seam by pressing it exactly as I pieced it. This warms the fibers to make them easy to position. Then, I gently finger press the piece into place. Then, I press again with the iron. Finally, I use a clapper (block of wood) to pull the heat back out of the fibers and help the piece stay flat. You can starch again during pressing if desired.
Closing Thoughts
Triangles and other pieces that use bias edges get a bad rap for being “hard” because they require attention to detail when it comes to bias edges and points. Follow these, tips, though, and I think you’ll find that they just require a bit of care to come out sharp, crispy, and very satisfying.
