Chapter 26 Basic Sewing Skills 451 Press the seam open. Trim all notches and frayed edges. Using a single thread, sew a loose overcast stitch. Do each seam allowance separately. Machine Overcast Sergers and some sewing machines can make a machine-overcast fi nish. Firm, medium-weight fabrics are candidates for this type of fi nish. The stitches are more bulky than hand-overcast stitches. Press the seam open. Stitch through a single layer of the seam allowance. The needle should move back and forth across the cut edge of the seam allow- ance. It should reach only slightly outside the cut edge. Seam Treatments In some garment areas, a regular seam allowance is too bulky. This is espe- cially so in enclosed areas such as necklines, collars, and cuffs. Curved seams and corners also will be bulky. You can eliminate this bulk by trimming, grad- ing, and clipping seams. Trimming Trimming is cutting off part of the seam allowance. To trim a seam, cut away part of the seam allowance, leaving a ⅛ - to ¼ -inch seam allowance. Curved areas, such as the underarm section of an armhole seam or the center back seam of pants, are usually trimmed to ¼ inch. Trim corners and points before turning and pressing them. Collars and cuffs, for example, will lie smooth and fl at if you trim them before turning. To trim a right-angle corner, cut diagonally across the seam allowance. Cut close to the stitch- ing, but not through it, 26-14. Grading For heavier fabrics or for places with three layers of fabric, grading is better. Grading involves trimming each seam allow- ance to a different width. This prevents a ridge from show- ing on the outside of the garment. Enclosed seams— such as collars, cuffs, pockets, and facings—are good candidates for grading. When grading a seam, make sure the seam allowance closest to the outside of the garment is the widest. This will prevent press marks from showing on the fi nished side of the garment. Trim this seam allowance to ¼ inch. Trim the other seam allowance to ⅛ inch. If a corner has a sharper point, as the one in 26-15, cut diagonally across the seam allowance. Then make another cut on each side of the corner to remove the extra fabric. Clipping and Notching Curved seams will not lie fl at unless they are clipped. Clipping is making straight cuts into the seam allowance. It is done after the seam is trimmed or graded. 26-14 To remove bulk, trim seams to ⅛ inch or ¼ inch. Trim corners at right angles. Goodheart-Willcox Publisher