Biased: Introducing Bias Cut Fabric

We talked last time about the construction of fabric and what " straight grain" means.

From Threads Magazine

Basically it means the fabric is cut along the line with either the warp grain( the long threads of the fabric) or the weft grain, (the threads going across).  Fabric is just woven threads. It's not static. The threads can easily shift within the fabric.So it can stretch, warp, or shift on you in a moment's notice.  The straight of grain fabric does that slightly. But what if you cut at a 45 degree angle across the square. The picture shows us a log of thread ends with nothing to hold them in place. That 45 degree cut is a bias cut. And since the threads aren't holding each other in place, it stretches. Not just a little bit. A lot! 

Is that a good thing? Again, nothing is  good or bad but thinking makes it so.

You may think this talk about grain doesn't matter to beginner sewers, or people making simple quilts. But it helps you predict how fabric will react as you sew it. And if you think it through, you'll understand some of the problems involved with sewing bias and some of the solutions.

Elizabeth Hartman from Oh, Fransson!

Remember how we talked about half square triangles, and how many different kinds of blocks you can cut from them? That seam across the half square triangle is bias cut. Any quilt we make with triangles or diamonds by definition has a bias seam, waiting to stretch out before your eyes. 

Before you start to panic, quilters have dealt with this from the beginning of quilting. And knowledge is power. Are you wondering why one square is bigger than the other? Pointed slightly differently? Why the seams don't match. It could be due to bias stretch. Here's some ways to control that,

From Exuberant Color

Bias coping skills

• The simplest thing to do about bias is to remember not to stretch it. Don't pull it through the machine. Don't tug it into place. Don't encourage it to stretch more than it does just in sewing.
•  Cut accurately and trim to even things out rather than stretch a seam to make it match.
• Use a walking foot to make your fabric feed evenly top and back side. A walking foot grabs fabric from both the top and the back side.
• Use pins. A lot of pins
• Don't drag your iron along the seams. Lift it. Place it. Let it steam. Repeat.

If it stretches a little, that's fine. Just don't encourage it to stretch a lot.

From Nettie at aquiltisnice

Is there an upside to bias? Actually yes there is! That curve you see on this bound edge is from cut bias strips. The bias stretches nicely to accommodate the curve. Many quilters use bias binding because that stretch leaves a smoother bound edge.

We'll talk more about bias binding next time!

Sewing Against the Grain: Knowledge is Power

Thermoweb.com

When most of us start to quilt we usually start with projects that look pretty easy. Square pieces, simple straight lines. So why is it that we're sewing along and all of a sudden the seams we pinned don't match and one side is a lot longer than the other.

We think of fabric as being square. That's not really true. Fabric is thread woven. Those threads can and do shift within the fabric. Fabric is only square if we cut it square. And that can change when we pick it up and move it.

Illustration Janet Wickell

The secret is in the weave. The long threads of your fabric going down the length of your cloth  (the weft) are tightly stretched in the weaving. The threads that go back and forth between the edges of your cloth ( the weave) is placed between the stretched weft. They don't have the same tension on them so they are never as tight. What does that mean? The weave edge of your fabric is stretchier than the weft.

When we're cutting our fabric we think of straight of grain. Both weft and weave are straight grain. But they don't act the same way. The weft is much more likely to stretch. And it will stretch right under your sewing machine foot.

Is this a good thing?
A bad thing?
Nothing is good or bad if thinking makes it sew.

Back to our seam. It makes sense if you sew a weft cut piece to a warp cut piece that one will stretch more. Here's some strategies that help us work around that.

• Pin everything well. It will move some. We just want it to move less.

Janet Wickell About Quilting 

• Cut cleanly. Clean rotary cut fabric is  is always easier to sew because it's more accurate. It's impossible to sew torn fabric evenly because the edge stretches in the tear.

• Consider sewing strips and cutting them in segments for construction. It's much more accurate.
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• Even up squares before you stitch them together. You're seams aren't completely even in the block? A swift round of rotary cutting each block to exactly the right size can save you a lot of trouble later.

  

  Amanda Herring The Quilted Fish

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• Sew long strips together from the same side. I know it's awkward. But your strips will stretch the same way and iron much better.
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• Use a sewing machine foot that helps you keep your seams even.  A  consistant 1/8 inch discrepancy in a nine patch makes for blocks that can be 3/4" different in size. Accuracy does count.

  

  Faith Jones of Fresh Lemons Quilts

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• If you have one side of a piece your piecing that is longer, you can put that on the bottom. The top will stretch and the bottom will not.
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• Finally figure out how much accuracy matters to you. You are the only judge here. If you're happy with your results, no one else gets a say about that. My grandmother's quilt seams didn't match either. I'm upholding a fine tradition.

Janet Wickell has a great article fabric grain  at  quilting.about.com.

Faith Jones also has a great article for making seams match on Quilting Gallery. 

Next time we'll talk about the exception to all of this, bias.