One of the most common tasks in altering is changing the length of a hemline. The first step is to take out the old hem and press the allowances flat. Next, determine exactly where you want the hem to be. Then press the hem allowance under along this new hemline.
Before you can decide how best to hem the garment, you need to determine how much flaring or tapering is going on at the bottom couple of inches of the garment. Check for this by laying your garment flat and folding the edge up a couple of inches. If the width at the bottom edge is equal to the width of the garment where it's lying, your hem allowance will lie flat. If the bottom edge is wider, your garment flares. If it's narrower, your garment tapers.
Straight Hem Allowances
Exactly how you proceed will depend on the weight of the fabric. Heavyweight fabrics, such as jeans or denim skirts, should be hemmed to minimize bulk. Hems on jeans are usually turned twice. Press the raw edge up to the desired length. Trim the allowance to 1″ of your fold line. Fold the raw edge almost to the fold line. Machine-stitch the hem in place with a straight stitch, using a heavy-duty needle.
An alternative is to trim the hem allowance to ½″ and finish the raw edge with a zigzag or other finishing stitch. Fold the hem up and machine-stitch. You will still need a heavy-duty needle but will be sewing through two layers instead of three. A neater version of finishing the raw edge of heavy to medium weight fabrics is to overlap the very edge with seam tape. Machine-stitch the tape to the edge and stitch the actual hem along the other edge of the tape. This will hide the raw edge on the inside while allowing you to stitch through fewer layers of the dense fabric.
Lightweight fabrics are nearly always turned twice. Trim the hem allowance to anywhere from 1 to 2. Turn the raw edge under ½″. Pin the hem in place and hem with a machine hemstitch or by hand.
Machine hemstitch: Fold the fabric carefully so your stitches are even.
If you have a hemstitch on your machine, this would be a perfect time to try it out. Adjust the pins so they run parallel to the edge instead of perpendicular. With the wrong side toward you, fold the hem back under the main fabric, exposing about ⅛″ of the hem edge. Stitch along this edge as shown in FIGURE 4-5. The hemstitch consists of three or four straight stitches that go through the hem edge, followed by one zigzag stitch that extends over onto the main fabric. On the outside, it will look much like a hand-stitched hem. Care must be taken to keep the fabric folded so that the zigzag stitches extend into the main fabric at approximately the same distance.
If you prefer to hand-stitch your hem, refer to the hand hemstitch illustration and description earlier in this chapter.
When raising a hem, the temptation is to fold over an existing hem in case you want to lengthen the garment later. Do this only for a fast-growing child and only if you are confident the article won't wear out before it's outgrown.
Flared Hem Allowances
If your hem allowance is flared, you will need to gather the edge of the fabric slightly to make it fit. The best way to minimize this is to make the hem as narrow as possible. Also, because the gathers will add bulk, finishing the edge with zigzag stitches or seam tape is preferable to folding the edge under on any but the lightest weight fabrics. Lace seam binding can be helpful here. Stretch it slightly as you stitch it to the raw edge.
You will have to be especially careful pinning the hem in place so your gathers along the hem edge will be at the appropriate places to make the finished hem lie flat. Extremely flared hems will be difficult to ease in with the machine and should be hand sewn. If you are using seam tape or lace, take a running stitch, that is, tiny in-and-out stitches in the tape edge between the stitches that go through the fabric underneath. See FIGURE 4-6.
Stitching flared hems with binding: Gather the excess allowance until it fits between the pins.
If you are folding the raw edge of your hem allowance under, use the longest stitch setting on your machine and stitch along this single fold. Pin your hem in place. With a pin, pull a few of the stitches between the anchor pins to gather the edge. See FIGURE 4-7. Hem with the regular hemstitch by machine or by hand.
Stitching flared hems with turned edge.
Tapered Hem Allowances
Tapered hems are the most difficult. Essentially, you need to gather the garment to fit the hem, but you don't want it to show that you've done that. If you were constructing a new garment that tapered, at the point where you wanted the hem to fold, you would flare out your garment pieces to make up for the taper. With a ready-made garment you are altering, it's too late to do that. Instead, make the hem as narrow as possible and place your stitches a little farther apart to minimize the pinched look on the outside.
Lowering a Hemline
If you want to shorten a ready-made garment, you will have plenty of hem allowance to work with. Lengthening a garment is a different matter.
First of all, there has to be enough fabric in the hem allowance to work with. Unless it is a garment that lends itself to some creative inserts, trims, or ruffles, you'll want the lower hem to be part of the garment fabric itself. After ripping out the original hemstitches, use seam binding to minimize the amount of fabric you will need. Sew the seam binding to the raw edge so it just barely overlaps onto the fabric. Fold the seam binding under enough that it doesn't show and hem. This will use only about ¼″ of fabric.
The other problem with lowering hems is the crease from the old hem. The crease can be difficult to press out even in new garments, and garments that have had some wear will almost certainly have a permanent crease line. If these are everyday clothes for a growing child, ignore the crease. If you are altering dress pants to fit a taller person or a skirt to reflect a new, longer style, consider whether the finished product is going to be satisfactory enough to make it worth the effort.
To tell if a crease is going to show before you take out the old hem, separate the two layers of fabric at the hem. If the fold line appears lighter than the fabric around it, it's going to show.