The "French" seam joins and encloses the seam allowance. It is used on sheer, fine fabrics, where the seams will show. Place the fabric wrong sides together, aligning raw edges. Pin if desired. Join the fabrics using a 3/8" (1 cm) seam allowance. Trim the seam allowance to 1/8" (3 mm). Fold the fabrics right sides together, along the seam. Press. Sew a 1/4" (6mm) wide seam, enclosing the previously sewn seam allowance. Press the seam allowance in one direction.