Fabric Bias and Binding Handout

Fabric Bias and Binding
presented by Honorable Lady Simona della Luna
at King’s College 2016 in the Barony of Namron, Kingdom of Ansteorra
m.k.a. Star Maddox Star.Maddox@gmail.com  

loom illustration by Pearson Scott Foresman, from Wiki Commons
original woven fabric illustration by PKM at English Wikipedia, modified by Star Maddox

A glossary and a list of additional resources may be found at the end of this handout. The most up to date version of this handout may be found at http://lavorodellaluna.blogspot.com.

What is bias
When woven fabric is made, the loom is set up with long warp threads. Then the weft thread is passed from left to right and back agin, forming the cloth. Sometimes the warp and weft threads are the same fiber, strength, and spacing, and sometimes they are different. The far left and right edges of the cloth are woven in a slightly different style, forming the non-fraying selvage edges. If a strip of cloth or pattern piece is on the straight of grain, it is in line with the warp threads. If it is on the cross grain, it is lined up with the weft threads. If it is on the bias, it is oriented at a 45 degree angle to the warp and weft threads. The grain line marked on pattern pieces is intended to be matched to the straight of grain, though for some fabrics the cross grain will work as well, as long as the warp and weft threads are the same.

Bias tape
Strips of fabric can be cut on the bias, creating bias tape. This tape may be 1/2” to 3” or more. It may be left unfolded, or it may be simple fold, single fold, or double fold.

Why use bias tape
  • As trim, especially to go over a slightly curved area like a bodice front. If there’s a lot of curve you may be better off using a more flexible cord, or cutting the trim fabric into the curved shape.
  • Finishing the edges of unlined items (especially necklines, arm holes in sleeveless tops)
  • As a colorful design element
  • To finish raw edges of seam allowances, a practice called a Hong Kong finish. This can add structure to an unlined jacket or trousers.
  • As reinforcement to areas that may take heavy wear, as when bias binding is applied to the inside of the armhole seam of a tailored doublet or suit coat, even though that area will be covered by a lining.
  • To finish and encase the edges of multilayer items, like a quilt, padded arming coat, or corset
How to make bias tape
Most stores that carry fabric and sewing notions also carry a wide range of pre-made bias tapes, with a selection of sizes and colors. Store bought bias tape is convenient and relatively inexpensive. However, many makers prefer to cut their own. Home made bias tape allows the maker to choose exactly the right color, material, and size for the project, and often gives a more durable result because you can use a higher quality of fabric than most store-bought bias tape is made of.

Since the fabric grain is so important to bias tape, don’t rely on the cut edge from the fabric store. Wash, dry, and iron the fabric. Then at one cut end, pull a thread for a straight line: carefully clip into the edge of the fabric near the cut edge, and separate out a single weft thread. Gently pull on it, sliding it out of the fabric. If it breaks, use scissors to cut in the gap left by the thread that did come out, and re-start the line. Continue all the way across the fabric. The result is an edge that is perfectly straight, grain-wise. If the fabric seems somewhat warped, use a steam iron to straighten it. A tutorial on this technique is listed in the Additional Resources section below.

Determine the cut width required for the bias tape. This depends on both the desired size of the finished bias tape, and the type of bias tape, since some styles are folded smaller. For double fold bias tape, the cut width is the desired finished width multiplied by four. So if the finished garment should have 1/4” of binding showing on the front, the cut width would be 1”. Wider tape is less fiddly to work with, but can be very difficult to make lay nicely when going around sharp inside curves.

Using a straight edge, cut along the bias near one cut edge. Offset the line by the cut width and cut again, repeating to make more strips. Be careful to keep an even width, and do not allow the straightedge to become slightly tilted. Cut enough strips to run the needed length, plus at least the width of the tape per seam required to piece together the needed number of strips, plus another 6” to allow for joining the two ends when they meet up again (for a binding a neckline, quilt, or hem).  

To join the strips together, pin the ends of two strips right sides together, at right angles to each other, offset by the 1/4” seam allowance. Stitch a seam at a 45 degree angle to the two strips. Clip the excess fabric beyond the 1/4” seam allowance and press the seam open. Attach the next strip in the same way, making sure that all seam allowances end up on the same side. A method for making continuous binding is listed in Additional Resources. It is a more complicated process, but much more efficient for making large quantities of bias tape.

If the freshly-cut strip of bias fabric is folded it in half lengthwise (right side out), the result is simple fold bias tape. Simple fold bias tape might have a cord stitched into its fold to make piping, or it might be used as binding. If instead the fabric has its left and right edges folded toward the middle (but not meeting), the result is  single fold bias tape. If single fold bias tape is folded nearly in half lengthwise (with the fold line just slightly off from the middle), the result is double fold bias tape. The off-center fold gives one side slightly more length to accommodate stitch-in-the-ditch when attaching to an item, so the longer side must end up on the back side of the item. 

A bias tape maker is a small somewhat cone-shaped metal tool that aids in the folding of single fold bias tape. A cut strip of bias fabric is inserted into one side, and the tool is gradually slid down the length of the strip, followed close behind by an iron to set the fold. They are available in a variety of different sizes, since each different size of bias tape requires its own size of bias tape maker. I find I only ever use the 1/2” size.






How to use bias tape
Attaching bias tape is usually done with two lines of stitching. First the bias tape is pinned in place on the garment. If an edge is to be bound with double fold bias tape, line up the narrower edge of the bias tape with the raw edge to be enclosed, with both right sides of the cloth facing each other and the bias tape laying on top of the garment. Machine sew a line of stitching to attach the bias tape. The seam  allowance you use will determine the amount of bias tape that is visible from the outside of the garment. Next, fold the bias tape along its pre-marked fold lines, wrapping it around the garment’s raw edge and folding the raw edge of the bias tape inside. The uneven fold of the bias tape will cause the inside edge of the bias tape to project slightly past the first stitch line. From the outside of the garment, stitch in the ditch - carefully run another stitch line through all the layers, staying in the crease of the first stitch line and catching the longer back fold. The second stitch line is visible from the inside of the garment, but not the outside, and the result is clean and tidy looking.

If you are using a machine to sew, but would prefer not to have any visible machine stitching (even on the inside) you can use a whip stitch or blind stitch to secure the second stitch line, being careful to go only through the inner layers of fabric, and not letting the stitches show through to the outside.

Another option that may work better for hand sewing would be to use flat bias tape, without a pre-made fold. To encase an edge and give a facing on a garment that will have a lining inserted, first line up one cut edge of a strip of un-folded bias tape with the raw edge to be enclosed, with both right sides of the cloth facing each other and the bias tape laying on top of the garment. Stitch the bias tape in place with a running or back stitch. The seam allowance you use will determine the amount of bias tape that is visible from the outside of the garment. Next, fold the bias tape to the inside of the garment, wrapping it around the garment’s raw edge and smoothing the remaining bias tape flat against the garment. Carefully whip stitch the cut edge of the bias tape to the inside of the garment, using small stitches through the interlining that won’t show on the outside of the garment. When you insert the lining, fold the cut edge of the lining to the inside of the garment’s layers and whip stitch or blind stitch it in place. 

Mitered corners are often used any time the bound garment has a sharp corner. The bias tape is attached in a way that gives a diagonally folded line at the corner. This method gives a much nicer finish than simply stitching the bias tape across the corner with horizontal seams. A video tutorial showing how to do a mitered corner is in the additional resources section.

Glossary
bias, or bias grain - “true” bias runs at a 45 degree angle to the warp and weft threads, to give maximum stretch and drape. “Slight” bias may be less than 45 degrees. If unspecified, the intent is the full 45 degree angle.
bias tape - a strip of fabric, usually 1/2” to 3” or more, cut on the bias. It may not be folded, or it may be simple fold, single fold, or double fold.

cross grain - in line with the weft threads, aligned from one selvage edge to the other. Sometimes also called straight grain, though this is not technically correct, and it can mater on some fabrics with a difference in texture or stretch.
double fold bias tape - single fold bias tape which has been folded again lengthwise. The fold is off-center, giving one side slightly more room for stitch-in-the-ditch when attaching to an item.
mitered corner - a corner with a diagonal seam running from the inside of the corner to the outside point, and no horizontal seam
selvage - the non-fraying edges of a length of cloth as it comes from the loom
simple fold bias tape - bias tape that has been folded in half along the center, lengthwise
single fold bias tape - bias tape that’s had its left and right edges folded toward the center; the edges may have a small gap between them rather than meeting
stitch in the ditch - a sewing technique where a new line of stitching is laid down at the join of two previously-attached pieces, with the new stitches partially hidden by the “ditch” formed by the previous seam.
straight of grain, or straight grain - in line with the warp threads, aligned along the length of the fabric as it is rolled on the bolt. Sometimes cross grain (see above) is also called straight grain, though this is not technically correct, and it can matter on some fabrics with a difference in texture or stretch.
weft - the threads woven by the shuttle of the loom, going from one selvage edge to the other
warp - the threads that run the entire length of the cloth as it is rolled on the bolt (can be 10 yards or more, depending on the mill)

Additional Resources
Ripping a straight edge, pulling a thread, lining up your pattern:
Correcting the grain on woven fabric, if it’s gotten a little warped:
Making continuous bias binding, with instructions and the math behind it all:
Video tutorial on joining binding strips, mitered 90 degree corners, and finishing the join:
Finishing a neckline with hidden bias binding (none shows on the outside of the garment):
Further description of bias, making homemade bias tape, and sewing it to an item:
Video of how to use a bias binding foot:

This work is licensed under the Creative Commons Attribution-ShareAlike 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/4.0/
You should read all the specifics on the website, but the quick version is that you can use this document, or part of it, as long as you say where you got it (text author is Simona della Luna m.k.a. Star Maddox, image credits are either same as text author or are noted with the images), and as long as you let other people use the thing you make with this work (“share alike”). So if you want to use this handout for your class, please do! It’s not required, but if you find this handout useful or have suggestions, I’d like to know. Email me at star.Maddox@gmail.com. 







1 comment:

Subscribe to: Posts (Atom)