What is a Hong Kong Seam finish
A Hong Kong seam finish is applied using a single layer bias strip that wraps around the seam allowance edges to prevent them from fraying and provide a semi-decorative finish on the garment's wrong side. The bias strip width is chosen based on the fabric thickness- it should be wide enough to securely encase the seam allowance raw edges but not to so wide that it creates unwanted thickness and bulk. Mot bias strips used in a Hong Kong seam finish are a standard 1-1 1/2" wide. The beauty of a Hong Kong finish is that the bias strip excess width can be trimmed down at the end, on the application's underside along the bias strip lengthwise edge left unfinished.
On the application's right side, the bias strip is stitched to create a folding effect over the seam allowance surface. On the wrong side, the other edge of the bias strip is left unfinished and simply stitched down to permanently enclose the fabric seam allowance edge. This final stitch is applied next to the folded bias strip edge on the application's right side such that it looks almost invisible on the face of the finished seam. You can look at a Hong Kong seam finish as a simpler version of a bias bound finish.