Bias Bound Seam – Binding Seams in 3 Steps

A bias-bound seam is a professional seam finish in which bias tape is sewn over the raw edges of the seam to prevent fraying and create a clean, decorative interior. This couture-inspired seam finish is especially popular in unlined jackets, skirts, coats, and tailored garments where the inside of the garment deserves just as much attention as the outside. Bias-bound seams not only strengthen and neaten seam allowances, but they also add beautiful color and pattern details inside garments. In this tutorial, you’ll learn how to sew a bias-bound seam step by step, the difference between bias-bound seams and Hong Kong finishes, and the best fabrics to use.

What is a Bias Bound Seam?

A bias bound seam is a seam that is finished with bias binding, so the raw edges are covered and will not fray. The binding can cover both edges of the normal seam together in one operation, or the bias can be sewn to each side of a pressed open seam. The choice depends on the thickness of the material and the desired overall effect for the inside of the garment.

If you are learning decorative seam finishing techniques, explore the full types of seams guide to compare enclosed and bound seam finishes.

This bias bound seam technique suits unlined jackets, skirts, and garments that could have been lined. The bound seam does the trick of finishing the seams and adding interesting colors and patterns to the inside of the garment. Imagine spots, stripes, or even pretty flowers inside your garment. It is generally more economical than double fabric sewing a full lining.

How to Sew a Bias Bound Seam (Step by Step)

Here are the step-by-step instructions to bind a seam:

1. Sew the Seam

Put the right sides together and sew the seam with a wide seam allowance. The stitching line should be at least 1/2 inch (12mm) from the edge. Decide if you want to bind the seam allowances open or sew them together with one binding.

Then select the bias strips you plan to use. The most common type of binding used to bind seams is 1/4 inch (6mm) double-fold bias tape. If you have some 1/2 inch (12mm) single-fold bias in your sewing room, you can save money by pressing it in half. But don’t forget to press with the bottom edge slightly wider than the top.

If you are adventurous, making your own bias binding provides endless possibilities for choosing contrasting colors and patterns to finish off your seams.  Measure up and make sure you cut enough to finish the job.

2. Encase the Raw Edge

Open your strip of bias tape and encase the raw edge, making sure to put the slightly narrower side of the tape on the top of the seam. This means that when you sew through the tape, the underside, being the wider side, will automatically be caught in.

3. Stitch the Bias Tape

Stitch the edges of the bias with a straight stitch. Note that you are only sewing the seam allowances. The main fabric underneath is not caught in. Repeat for the other side of the seam allowance.

Don’t forget to press when you have finished, as the tailored look of the bias bound seam depends on creating neat and clean edges. If you have bound your seam allowances together rather than separately, press them to one side when finished.

Bias Bound Seam vs Hong Kong Finish

These types of bias seams are similar but not the same!! The Hong Kong finish binding is stitched slightly differently, and the end result after stitching into the ‘ditch’ of the seam is that no stitching is visible on the right side of the seam in the garment. See how in the photo below, no stitching is visible on the bias edges.

Play around with both types of seam finishes, and then if you are happy with the bias-bound seam and its stitched effect, go ahead and use that for your flashy jacket. I find the bias bound edge to be the faster of the 2 methods, but the Hong Kong seam tends to look neater.

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Bias Bound Seam FAQs

Bias Bound Seam – In Conclusion

Bias bound seams are one of the most beautiful and practical ways to finish raw seam allowances. They create clean professional garment interiors while adding decorative color and detail that make handmade garments feel truly special. Once you learn how to sew bias-bound seams, you can use them to elevate jackets, coats, skirts, bags, and many other sewing projects with couture-inspired finishing techniques.

More Articles On Bias Tape

1. How to Make Bias Tape
2. How to Sew Bias Tape
3. How to Make Continuous Bias Tape
4. How to Sew Mitred Square Corners with Bias Tape
5. Bias Bound Seam
6. Hong Kong Finish
7. How to Sew a V Neck with Bias Tape