The French seam is a bulky, self-finished seam that is great for delicate fabrics that fray.
It is used on garments that are washed a lot like lingerie, and blouses.
You will also find French seam used on children's and babies clothing.
It is found on babies clothes for two reasons, one, so that the seam allowance doesn't rub up against the baby's soft skin.
A traditional seam allowance will have a zigzag finish or serger finish that can be rough on a baby's newborn skin.
And two, it holds up well with clothes that are washed often.
With a French seam, the raw edges are completely enclosed within the seam.
It should not be used on bulky fabrics or curved seams.
Unlike, most seams made in garment making where the fabric is sewn pretty sides together, the French seam is made by sewing the fabrics wrong or ugly sides together.
How to Sew a French Seam: To sew a French seam pin the fabric wrong sides together and sew a ¼" seam allowance.
Trim the seam allowance but be careful not to cut into your stitches.
Press the seam allowance to one side.
Turn the fabric so that the right or pretty sides are together and roll the seam between your fingers and thumbs so that the stitching line is right on the edge.
Press flat.
Stitch in place.
Press both wrong side and right side of fabrics with the seam lying towards the back of the garment.
Notice there is no raw edges or fraying.