I discovered a great technique for finishing seams and underlining in one – it ends up looking like a cross between a French Seam and a Hong Kong finish. It’s a perfect solution for silk or other fabrics prone to fraying, like my recent silk faille Simplicity 2343. I’m not sure from where it originated, but there’s a text tutorial on Pattern Review and a few bloggers have written about it before. However, I struggled to understand the instructions without some photos, so I thought I would put together this little tutorial for you! Hope you find it useful. The instructions below assume that your patterns has a 5/8 inch seam allowance.
1. Cut your underlining 1/2 inch wider than the fashion fabric on each vertical seam (i.e. the whole piece will be 1 inch wider).
2. Sew the vertical edges, right sides together, using a 1/4 inch seam. Because the underlining is bigger, it won’t sit flush to the fashion fabric.
5. Now treat the fashion fabric and underlining as one piece! When you sew it together, you’ll have lovely 1/8 inch wrapped edges. Remember that you trimmed 1/8 inch off the fashion fabric, so sew up the vertical seams with a 1/2 inch seam allowance.