Bias 101 - Threads


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Bias 101

Add drape to fabric by cutting it on the bias
Straight grain vs. bias.
Three steps to change straight of grain to bias
Add drape to fabric by cutting it on the bias

Add drape to fabric by cutting it on the bias

by Marcy Tilton
from Threads #76, pp. 34-39

The bias is spoken of in hushed, reverential terms in the fashion world. Only a few designers ever master the bias cut, and very few home sewers dare to take the plunge. But by choosing a stable fabric and a simple pattern (a combination I call my "bias training wheels"), and by following a few step-by-step guidelines, you can be assured of success with bias-cut garments.

Straight grain vs. bias Straight grain vs. bias
The bias runs at an angle to the straight and crossgrains, with the true bias running at an exact 45-degree angle
Add drape to fabric
Add drape to fabric by cutting it on the bias. If you start with a stripe, you can also create beautiful chevron effects at seams. Above, bias binding adds a contrasting detail at the neck edge; you can also use a corded piping. Photo: Laura White.  

Grain refers to the straight and crosswise direction of the yarns making up a woven fabric, with bias running at any angle to the straight and crossgrains and the true bias running at a 45-degree angle to these grains, as shown in the drawing above. Garments cut on the bias appear softer and more fluid, have more stretch, and are more supple than those cut on the lengthwise or crosswise grain. The fabric also appears "thinner" than the same fabric cut on the straight grain.

Bias garments need more fabric than the same garment on the straight grain, and are best cut one layer at a time so the grain doesn't distort. Working on the bias requires a bit more time, a careful selection of fabric, as well as some alternate fitting and sewing techniques, which I'll explain in detail.

I suggest starting with a simple top or a sleeveless tank or shell. Cutting the top on the bias instantly makes the shape more fluid and gives the fabric a more interesting character. Use a pattern you've sewn before, or make it up quickly in muslin to test the fit before you begin.

Safe fabric choices for bias
Begin at the fabric store by unfurling a few bolts of fabric and folding each on the diagonal to get a feel for the way the fabric responds and feels on the bias. Compare different fibers, weights, and textures. Notice how much the fabrics stretch on the bias, how a plain weave takes on a new texture, a twill weave loses its definition, and plaids and stripes become diagonal lines.

For your first few bias-cut tops, pick user-friendly, natural-fiber fabrics with "tooth" (the layers tend to grab each other), like cotton, linen, silk broadcloth, or wool challis. I look for fabrics with a plain weave and minimal texture, and I love the effect of stripes cut on the bias. Beginners, however, should choose a narrow, 1/4-in. or smaller stripe so it doesn't have to be matched.

The short list of fabrics to avoid for bias includes most rayons (stretches like crazy), silkies and polyester (slippery and hard to handle), twills (lose definition), and fabrics that are heavy or stiff, like duck or poplin. Silks and sheers like crepe de chine, charmeuse, and georgette are beautiful on the bias, but these hard-to-handle fabrics aren't a good place to begin. Move up to silky fabrics once you've conquered the stable ones.

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Comments (5)

Thornie Thornie writes: What an excellent post!! I was struggling along with a skirt pattern I just made, knowing it should really be bias cut but feeling a little lost and unsure when I found this. Thanks for the clear instruction!
Posted: 5:10 pm on January 29th

Dooner Dooner writes: In a bias cut skirt, are the unseen inside pouch-pockets cut on the bias also?
Posted: 7:51 am on April 29th

rumpole rumpole writes: i have been looking for instruction on how to cut a simple skirt on the bias. i made the skirt on the grain and it is nice but not 'floaty'. what do i do next?
Posted: 2:21 pm on September 20th

narrawallee narrawallee writes: I haven't sewn on a bias for years but after I read your article on sewing on the bias I gave it a go again and I love it I have made a couple of tops and I am going to make more and I love the feel of the material cut on the bias.

My projects website has a picture here: http://www.cathysews.com.au/Album/Tops/slides/bias-front.html
Posted: 7:03 am on April 30th

kapnoel kapnoel writes: Ever since I read your article, I have been changing lots of pattern pieces into bias. I absolutely love that! If cut generously a bias front on a blouse works wonders for my not so little tummy! Thank you!
Posted: 9:27 am on August 4th

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