|This isn't a new finish, its an old one remembered. Before zig zag machines and overlockers it was used a lot, but I'd forgotten it, until I needed to think of a way of neatening a seam in my 'my pattern contest' entry. I used it on the shoulder because the cut of the armhole could mean that in movement you might get a glimpse of the inners. Its a neat finish, neater than zig zag, not as bulky as overlock and no problems finding those huge spools of matching colour for a one off. I'm putting it here in case its useful to anyone else. You simply turn under a scant one eigth of an inch, 3mm,at the edge of the seam allowance, and straight stitch it, on each side of the seam, trimming back to the stiches. A cocktail stick really helps to control a slippery unobliging fabric as you feed that tiny turning under the machine foot. It makes it quite quick and painless. My first thought had been french seams, but on the fabric I was using the double seam made the shoulder area too stiff. This seam presses out flat, but looks neat, with only a line of straight stitch, and no fray.