Stretchy clothing has never been more popular. Leggings, bicycling and other sportswear, recreational and even some formalwear all take advantage of the freedom of movement offered by versatile knit fabrics that never wrinkle or fray.
Although knits are lovely to wear, they can be tricky to sew. In fact, if you’re a novice making your first garment ever, stretchy is not the recommended way to begin. Even sewers with years of experience are always learning new things about successfully using stretchy knit fabrics.
Before beginning to sew with knits, there’s a lot to learn about at least the most basic types of materials and how to handle them. The more you know, the better the finished product.
Where the Stretch Comes From
There are two basic types of fabrics, woven and knit. If you ever had one of those looms for making potholders when you were a kid, you know what weaving is. And if you know how or have ever watched someone knit or crochet, then you know the basics of how knit fabrics are made.
Woven fabrics are created by drawing straight threads left to right, under and over, through perpendicular straight lines, like basic basket weaving.
Knitted fabrics are made by manipulating loops of fabric through each other. Because of the way the threads are joined, the results have more room for give (stretch). Hand-knitted or crocheted items will generally stretch in multiple directions. Manufactured knit, or stretch, fabric comes in two types:
- 2-way (horizontal)–Some knits stretch only one direction, left to right. To confuse matters, these are sometimes called 1-way stretch fabrics.
- 4-way (horizontal/vertical)–These knits stretch both ways. They are sometimes called double knits or 2-way stretch fabrics. T-shirts and leggings are made from 4-way stretch material.
Types of Stretch Fabric
The back of most patterns offers a list of recommended fabrics. Before beginning a stretch project, it’s good to familiarize yourself with the various types of knit materials. Then you can make the correct choice at your local fabric shop or when purchasing online.
There are too many types of knit fabric to cover here. In-depth articles are available online to cover the topic in more detail. But I will mention some of the most commonly used choices.
- Jersey knits: This is probably the most popular 4-way stretch knit. Just some of the uses for jersey knit are leggings, T-shirts, and tank tops. If you look closely at jersey knit, you will see its resemblance to hand knitting. Jersey consists of straight rows of knitted thread, resembling a knit one row, purl the next combination. The lines seem to run vertically on the front and horizontally on the back of the material. The lightest knits are generally jersey knits, though heavier threads create heavier fabric.
- Rib knit: Up close, rib knit looks similar to a cuff or the bottom of a knit sweater. It is made with a knit-2, purl-2, or comparable combination in knitting. Consequently, rib knit has more obvious vertical lines. Rib knit is often a medium to heavy material.
- Interlock knit: Interlock knit looks the same on both sides. It is created using only a knit stitch and is available in varying weights.
These are the three basic knits. As mentioned, differences in raw materials create a range of fabric weights. And there are some knits without well-defined lines, such as boucle, Hatchy, polyester mesh, spandex, french terry, and lycra. It’s best to closely follow pattern suggestions until you have learned how different types of knits perform when worn.
Choosing the Right Stretch Factor
Since not all knits stretch the same amount, checking the actual stretch capacity is necessary before choosing the material for your pattern. One way to test the stretch is with a foot-long ruler and a 5-inch wide piece of fabric. Or line up a larger portion of cloth to cover only 5 inches of the ruler.
Hold the fabric firmly at the beginning of the ruler. Then grasp the end of the material and pull it along the ruler until it resists further stretching. Logically, if you can easily extend 5 inches of fabric to 10 inches, your fabric has a 100% stretch capacity. If it stretches to 7 ½ inches, it has a 50% stretch capacity, etc.
Along the side back of patterns used with stretch fabric, there is often a “pick-a-knit” rule that can be used to ensure at least 50% stretch capacity. The rule can be conveniently used at the fabric shop when purchasing a pattern and material during the same trip.
If you’re unsure about the complexity of the pattern and how it might behave with a knit material, you can try making a “test” garment with an inexpensive knit or even a light muslin fabric.
Choosing and Cutting Out Patterns
The best patterns for knit have simple lines and a minimum of extras such as darts or buttonholes. Stretch fabric is most commonly used for casual clothes and sportswear. But because of the soft drape of some knit materials, it can also be used for dressier garments.
Prepare the fabric by pre-washing it to avoid shrinkage issues later. However, it’s not necessary to pre-wash fleece, and washing could be damaging to knit vinyl.
Lightweight knits may curl along the edges, making it difficult to cut out patterns. One way to prevent this issue is by lightly applying spray starch and ironing. The starch can be washed out later if you desire.
Use a sharp cutting implement for knits to prevent snagging. Although they don’t fray or ravel, they do run. Don’t pull the edge as you cut or sew. Always cut patterns out on a flat surface for control and accuracy. Hold fabric in place with ballpoint pins or clips that won’t grab flexible fibers.
Fabric weights are also an option. Just be careful not to stretch the fabric as you place them. I love my weights, but they are more expensive than pins or clips. I have polished or tumbled rocks mixed in with my weights that work just as well. Use only smooth weights for stretch fabric.
If your pattern calls for interfacing, use a stretch product. Regular interfacing will pull the fabric out of shape as you move or tear away, losing stability and undoing the desired effect.
Machine Essentials and Stitches for Stretch Fabric
If you have one, a serger is the most recommended choice for sewing knits. But don’t worry if serging is not an option. Almost every basic machine has at least one stretch stitch option.
A coverstitch machine is also ideal for sewing stretch garments because it is designed to create the side-by-side parallel stitching hem found on T-shirts and leggings. It’s an idea to consider if you decide you really do love to sew knits.
Machine Presser Feet
There are also some handy presser feet to help feed knits evenly into the stitching area. You’ll have to research whether such feet are available for your model machine.
A walking foot is probably the most popular specialized foot for knits or other difficult fabrics. The walking (or even-feed) foot reaches out and pulls material for each stitch evenly along the plate.
It is absolutely essential to use the correct needle for sewing knits. Whether you’re using a serger or regular machine, look for stretch or ballpoint needles in a size appropriate to the fabric’s weight. These needles will slide easily through the material’s fibers without snagging and pulling. Using the wrong needle will cause pulled threads, runs, or puckers in your fabric. Begin a new knit project with a new, sharp needle for the best results.
If your machine can use a twin needle, it will be invaluable for stretch fabrics, especially for hems. Make sure your twin needles are ballpoint or stretch.
Regular weight polyester thread is sufficient for most knits. Cotton thread is not recommended as it will have a greater tendency to break as the material stretches.
Other thread options include American & Efird Maxi-Lock Stretch–with larger spools for sergers or regular machines, CESDes 3 Coats Eloflex, Coats S992-0100 Eloflex Stretch, or Embro All-Purpose for heavier materials.
Besides a basic serger stitch, here is a list of stitches appropriate for knits. Do not use a regular straight machine stitch since it will not stretch with the movement of the garment, resulting in breakage and gaps. Special stitches are needed to extend the expected lifetime of wear for knits.
Keeping scraps of different knit fabrics is a good idea. Use the scraps to test your stitching. Make any necessary adjustments to machine settings, the needle, and stitch choices before you begin sewing.
Since machines differ widely, you’ll need to consult your machine’s owner’s manual to determine the appropriate uses of the stitches available to you:
- Overlock serger–Use either a 3-or 4-thread configuration. Use test fabric to ensure the fabric is not being stretched out during stitching. Check your machine’s instructions for adjusting the differential feed control and use some scraps to ensure correct settings before starting to sew a garment.
- Chain stitch–This stitch looks like a hand-embroidered chain stitch on the backside.
- Cover stitch–As mentioned above, this stitch is available for specialized machines and requires a twin needle.
- Zigzag stitch–Adust your stitch width for a very narrow-width zigzag stitch for knits. This will allow extra movement for the fabric without a crinkly-looking seam.
- Tricot–This is a modified zigzag stitch. A tricot stitch creates three stitches in each zig and zag. Again, the tricot allows the fabric to stretch without easily breaking the stitches. This is also a very commonly available machine stitch.
- Stretch–A stretch (lighting bolt, stem) stitch looks similar to an embroidered stem stitch. The machine skips back slightly alongside the previous stitch for added stretching power. This is the most common stretch stitch and is available on almost all machines. Use a test piece in case you need to make some fine adjustments.
- Triple Straight Stitch–When finished, this stitch looks like three parallel straight stitches close together. The needle moves back and forth to make each stitch, giving extra leeway for stretch. Use scrap fabric to check thread tension for this one. A triple straight stitch is most appropriate for heavier knits.
- Twin needles–If your machine is set up for it, twin needles can be helpful for sewing knits. The needles create side-by-side stitches for extra strength and a more professional-looking hem.
Tips for Sewing Knits
Check Machine Settings
Check your machine settings before you start to sew knits. Run a test fabric for tension, stitch width, and stitch length. Review the instructions for any special adjustments for unusual presser feet.
Pin To Prevent Slipping
Pin or hand baste pattern pieces together to prevent slipping. Anchoring the pieces together is especially important when sewing a stretch to a non-stretch material. The results could be disastrous if the knit becomes stretched along the non-stretch piece.
Begin Away From The Edge
Lightweight knits can easily be drawn down into the bobbin area when you start at the edge. I have found it helpful to begin a little away from the edge. Extend the fabric so that the end is at the back end of the presser foot. You can then turn the piece around and finish the rest of the seam from further along the stitching to the edge.
Try Tissue Paper Underneath
If you find your fabric is simply too stretchy or too lightweight to sew well, try placing a thin layer of tissue paper beneath it as you sew. The tissue adds stability and tears away easily afterward.
DO NOT PULL ON STRETCH FABRIC AS YOU SEW! Pulling will result in a puckered or stretched-out seam. Allow the machine to do the work of pulling the fabric along. Use a light touch to guide fabric evenly through the sewing area.
Don’t Let Fabric Hang Down
It is also important not to let large pieces of fabric hang down, as the weight will pull on the fabric and affect the quality of the seam. Pull extra fabric onto the sewing table, or place an ironing board or small table next to the sewing table to support long pieces.
Choose The Right Zipper
If you need to add a zipper or buttons to a knit garment, use those appropriate for the project. Zippers are not stretchy, but a lightweight one will prevent undue stress on the material. Invisible zippers are also common for stretchy garments. Consult the notions section of your pattern for suggestions.
Use Stretch Interfacing For Buttonholes
Buttonholes are a challenge for some knits. Use stretch interfacing for extra stability. If you see more than one option on your machine, the one with the wider-spaced zigzag along the sides of the buttonhole is the correct one for knits.
It must be noted here that very lightweight knits may require hand-stitched buttonholes. Consider using a different type of closure that does not require buttonholes for such fabrics. For instance, you can use a hook or snap for actual closure and add a button for aesthetic value.
Snaps and Hooks
Snaps and hooks are both popular for stretch garments. Hooks are favored for their invisibility and holding power even as the garment moves around them.
Hemming Knit Fabrics
Hemming can present its challenges, but following the above mentioned tips should prevent significant issues. If you’d like to see hemming methods demonstrated before attempting it, many video tutorials are available.
If there is still a very slight waviness after sewing a seam or hemming, ironing at an appropriate temperature can often restore the garment’s shape for a more professional look. Don’t forget to use scrap fabric and experiment before sewing to prevent mistakes.