We are going to sew these two pieces of fabric together:
This is the part that feels strange. Line up your fabric with WRONG sides together and sew a 3/8" seam:
Measuring 1/8" out from the sewn line, trim off the seam allowance.
Fold the fabric on the seam so that right sides are together and iron it down.
Stitch another seam at 1/4" (this part feels normal again, because right sides are together--whew!).
When you open it up, it looks like this:
And from the back, it looks like this--see, no raw edges!!! Why all the precise measurements? To get a perfect 5/8" seam, of course!
If you can think of any ways that you would use or have used the French seam, PLEASE leave a comment.