Fabric Sewing Tips: Sewing Stretch Fabrics

Stretch knit fabrics are sometimes difficult to sew, but with the right needle, thread and technique, you can have do it.

Once you've learned to sew, you might think that all garment sewing is the same, but each type of fabric that you sew presents a new and different challenge. For sewing knit fabrics, the needle might have to be changed from your last cotton or denim project. Lightweight knit fabrics often require a size 10 needle, but for very thick knit fabrics, you might need a size14. The thread will also need to be different, most seamstresses opting for nylon thread rather than cotton. If you're using cotton thread, though, you'll need to loosen the tension on the machine. On most machines, you'll turn the tension knob to the left to loosen the tension, to the right to tighten. For knit fabrics, loosen the tension, and sew on a scrap piece of the fabric that you will be using for this project. Remove from under the presser foot and look at the stitches. The stitches should lay almost flat but be raised slightly, and when stretching the fabric, the stitches don't break. If you stretch the fabric and the stitches don't lay flat, you will have to tighten the tension just a tad. If you stretch the fabric and the stitches break, you'll need to loosen the tension a little more.

One obstacle when sewing knit fabrics is that seams tend to pucker. It's particularly true when sewing long straight seams, like the side seam of a dress, or when having to sew in a circle, like the insertion of a sleeve into the armhole of a shirt. There are machines which are made specially for sewing knit fabrics. They come equipped with a differential feed system which feeds each layer of the fabric through individually. The typical household sewing machine has a single feed which feeds all layers through at the same time. One way to test if your fabric will feed through evenly is to take two pieces of fabric, the exact same size. Sew a seam down the fabric, remove from under the presser foot and check the edges of the fabric. If they are still aligned, your feed is working well. If one edge of the fabric doesn't meet the other edge, your feed is pulling either the top or the bottom piece faster than the other. If your machine will allow you to adjust the feed, check which piece of fabric ended up shorter, and adjust that feed. When possible, sew stretch fabrics on a machine which has the differential feed, but if one isn't available, there are some tips and tricks you can use to sew the fabrics on a single feed machine. First of all, try to make the seams as uncomplicated as possible. If they are to be sewn once, then opened and top stitched, you will tend to see more puckering than if you just sew it once. Also, for single feed machines, ease the pressure on the presser foot and use the lightest weight thread possible for the fabric, to further prevent bunching. One more thing that will help prevent seams from gathering after laundering is to pre-shrink your fabric. Cotton fabrics shrink somewhat after laundering, but knit fabrics have a tendency to shrink considerably, so wash and dry the fabric before sewing.

Some other helpful suggestions are:

1. If your machine comes with accessories, check to see if there is a feed dog plate with a very small hole. This is the best plate to use, since it prevents stretchy fabrics from being shoved down into the hole when the needle hits the fabric.

2. Adjust your stitches-per-inch; smaller stitches allow less puckering at seams.

3. Whenever possible, cut the pieces so that they can be sewn on the bias.

4. Loosen the bobbin tension, but not loose enough for the stitches to form "loops" rather than stitches.

5. If these suggestions are followed, and there is still gathering at the seams, try changing the needle to an even smaller needle and try changing thread types.

It's best not to begin the project until you've perfected your stitch on a scrap piece of fabric of the same type that you will be actually sewing. When you start the actually seaming, thin bias tape is often a big help when going around necklines and armholes and there are some who even use it for side seams. Also, don't pull the fabric through the feed, even slightly. Allow the machine to feed the fabric, but guide it by placing each hand down flat on the fabric, one hand on each side of the presser foot. Hold the fabric down flat, but don't pull tight. You can have success when sewing stretch knit fabrics, but you might have to practice, switch notions and make other adjustments before seeing the best results.

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