French Seam
Sympkyn
A french seam is something my mother taught me, that she was taught to do to prevent fabric from fraying before the invention of the overlocker. I now use this method for medieval hand-sewn garments. I don’t actually have any evidence that it is “”period”” or historically accurate, but given that it’s a practical solution to fraying edges I see no reason to think that people in the past wouldn’t have used this technique. It’s elegantly simple. First, with wrong sides facing, pin and sew a running seam about 5mm from the edge of the fabric (approximately! Can vary depending on all sorts). I often sew this seam about 10mm in and then trim the rough edge back, if there is room to do so.
Then turn the right sides together and pin, enclosing the rough edges.
Sew another final seam to finish off. This last seam probably should be back-stitched if you want it very strong, but I tend to simply do another running seam, but neater and smaller stitches than the first. Sew far enough in that you are only sewing through two layers of fabric and are capturing all the edges inside the pocket being created.
The thing to be aware of is that this method uses about twice as much extra seam allowance all around than if you were overlocking the garment’s edges, so allow for this when cutting out and fitting.