French seam is a bulky, self-finished seam that is ideal for delicate fabrics that fray. It is used in garments that are washed a lot, such as lingerie and blouses. You will also find French couture used in children’s and baby clothing. It is found in baby clothes for two reasons, one, so that the seam allowance does not rub against the baby’s soft skin. A traditional seam allowance will have a zigzag or overlock finish that can be rough on a newborn’s skin. And two, it holds up well to clothes that are washed frequently.
With a French seam, the raw edges are completely enclosed within the seam. Not for use on bulky fabrics or curved seams. Unlike most seams done in garment manufacturing where the fabric is sewn on the pretty sides, French seam is done by sewing the fabrics on the wrong or ugly sides.
How to sew a French seam:
To sew a French seam, pin the wrong sides of the fabric and sew a ¼” seam allowance. Trim the seam allowance but be careful not to cut the stitches. Press the seam allowance to one side.
Turn the fabric over so the straight or pretty sides are together and roll the seam between your fingers and thumbs so that the seam line is right at the edge. flat press Sew in place.
Press both the right and wrong sides of the fabrics with the seam toward the back of the garment. Notice that there are no raw or frayed edges.