Bias Bound Seams give a quality finish to an un-lined garment and allow you to make a feature of your seams with contrasting or patterned bias tape, or to finish them neatly with a matching colour. If using a contrasting tape, make sure it wont show through to the right side.
Because bias tape is used, this finish works perfectly on straight and curved seams. See the pictures at the bottom of the tutorial to see how it can be applied to the inside seams of a coat. Whilst this kind of finish is usually applied to garment seams, it can also be used on home decor items and accessories.
A Bias Bound Seam uses double-folded bias tape to finish off a seam edge. The bias tape can be applied to both seam allowances separately (a pressed open seam) or to both seam allowances at once (a seam pressed to one side). This tutorial shows you how to apply the bias tape to both layers of the seam allowance at once. When doing this, keep in mind the weight of the fabric so that the seam doesn’t end up too thick!
How to sew a Bias Bound Seam – Tutorial
The width of bias tape you use is up to you. For my seam below, I have used a 6mm (1/4″) double fold tape. You can use pre-purchased tape or make your own. Either way, make sure you pre-shrink your bias tape. The last thing you want is for your tape to shrink AFTER you’ve put it on all your seams! If you are making your tape, then wash the fabric before you make the tape to sort out any shrinkage.
Sew your seam as you usually would, typically sewn right sides together. If following a pattern, use the seam allowance given in your instructions. You want the width of the bias tape to be less than your seam allowance. I have used a 1cm (3/8″) seam allowance.
If finishing your seam allowances together, press the seam to one side. Otherwise, press the seam open.
Take your bias tape and fold it around the seam allowance. Pin parallel to the seam. If one side of your bias tape is slightly wider than the other, put the wider side underneath.
Sew the bias tape close to the edge, catching both halves of the tape at the same time. All done!
Here you can see the finished seam from either side…lovely!
Above and below are some pictures of a coat I have that has all the seams finished in this way. Note that some of the seam allowances are finished separately, and some are finished together. Also note, that this looks great on curved seams. This finish can even be applied around armholes.