Our Sewing Glossary: What is a Bias Cut?

What is a bias? What is the use of a bias cut? Today I will answer these two questions, so if you don’t know what they mean, keep reading. As you might already know spun fabrics are composed of two threads, vertical warp and horizontal weft, that two run from side to side. The lines that draw these threads are known as straight grain. For woven textiles, grain refers to the orientation of the weft and warp threads. There are three common orientations: direct grain, cross grain and bias grain. Today we will focus on the bias grain, but I will cover more on the other grains in next posts. 

So let’s get back to the bias…you will find it by drawing an imaginary line at an angle of 45º with respect to the straight grain. Why is this grain so important? Well, fabric is considerably more elastic in the bias and easily deforms.

Bias of cloth

Source: Wikipedia

Another benefit of cutting the fabric in the bias or bias cut, is that it frays considerably less than the straight grain cut. Actually, I have come across some fabrics that won’t fray at all. And if you are looking to make curved fabrics, bias cut will be great for that, since they can also be sewn into rounded shapes and molded in such a way that they adapt to curves with the use of a steam iron.

Now that is great, but let’s get our hands dirty. How do we bias cut strips of straight grain fabric? Grab your most expensive fabric…just kidding, always when learning use cheap fabric in case you make mistakes. So, once you have your practice fabric, fold it in such a way that the weft and warp threads match. This will result in a perfect diagonal fold. Iron the fold and unfold it. It will be helpful if you mark the strip width you need using the fold line as if it was the edge. Tip! While you are making the cut with your scissors, be careful not to overstretch the bias while you’re holding the fabric. But what if you want to stretch the bias on purpose, for example, when using flexible fabrics such as the chiffon? You can pull the strip along its length and iron it later.

Do you have questions about the bias or bias cut? 🙂

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