How to sew stretch fabrics with a regular sewing machine
Hey y’all, continuing with the month of sewing knits, today we’re going to talk about different sewing stitches for knits. Stretchy fabrics seem to scare people new to sewing, and I’ve seen new sewists avoid knit fabrics even though they love to wear them. So let me reassure you that even beginners can work with knit fabrics using the tips in this series. Keep reading and watching, and soon you’ll be sewing your own knit garments.
Sewing Stretch Fabric 101
For those that are beginners to sewing knits, two main tips for success are to use a stretch stitch and a stretch needle. The reason you need a special stitch to sew knit fabric is because knit fabric stretches. Which means you need a stitch that stretches.
If you use a straight stitch the fabric will stretch and the stitch won’t, which means popped stitches. That is an experience I’ve had personally. So I thought that if I stretched the fabric as I sewed, I could use a straight stitch without my stitches popping. While that works to keep your stitches from breaking, it can also make your fabric stay stretched out and wavy.
The next idea I often see floated is to use a thread that stretches, like an elastic thread. It’s a logical thought. While this can also work, it can be hard to control the amount of stretch the machine’s tension dials add to the thread, especially in the bobbin thread. Which can result in seams that get gathered without you meaning to. It’s the opposite problem from stretching the fabric as you sew.
So if stretchy thread or stretching your fabric as you sew aren’t great solutions, what should you do instead? The answer is to instead use a stitch with side to side or back and forth motion.
Now that we know to use a stretch stitch, what kind of stitch stretches? And do you need a special machine to make it? The answers to those questions are the subject of the video below, where I demonstrate several stitches. If the video won’t load, you can also watch it on YouTube here. And if you’re not a video person, I’ve got a discussion of the stitches below.
Stretch Percentage and Recovery
Before we get into a discussion of how to sew knit fabrics, we need to talk about stretch percentage. Stretch percentage means the amount a given knit fabric can stretch before it severely distorts. So for example, below I have a 10 inch strip of knit that I can stretch to 14 inches before it starts getting really distorted. Those 4 extra inches divided by 10 (the total starting length) means that this fabric has 40% stretch. Now that we know this, we’ll be better able to compare the stretchiness of stitch types.
Recovery simply means how well/whether the fabric snaps back to its original shape. As you can see above, this fabric (a 95% cotton 5% spandex knit jersey) also has good recovery. For more about different types of knit fabrics, see this post.
Basic Stretch Stitches
Now let’s take a look at some stretch stitches. The basic stretch stitches that a regular modern sewing machine might include are zigzag, stretch or lightning bolt stitch, triple stitch, and twin needle stitch. Machines with many stitch choices might even have stretch buttonholes and a stretch blind hem. Your machine manual will be helpful in determining which of these stitches you can do with your sewing machine, as we won’t cover every possible stretch stitch in this post. With other types of sewing machines, you can also do a cover stitch, a chain stitch, and an overcast or overlock stitch.
First of all, you don’t need a special machine to sew knits. You can do it with your regular sewing machine as long as it can do a zig-zag stitch. The side to side motion of a zig zag means that it is a stitch that can stretch. In the video above, I compare the default zig-zag on my machine, which has a stitch length of 1.4 mm and a stitch width of 2.5mm, with a longer and more narrow zigzag stitch (3.5mm and 1.5mm). The first stitch is the stretchier of the two zigzag stitches, because the more back and forth the needle does, the more the thread has room to stretch.
Some machines, mine included, also have a specific stretch stitch. It looks like a lightning bolt, and it works kind of like a zig-zag, except the needle goes back a little bit to overlap the previous stitch. This means that the stretch stitch can look more like a straight line. You might see this stitch called a lightning stitch.
If your machine does both a zig-zag and a stretch stitch, I advise you to play with both of them. The zig-zag is often faster to sew, but it can look more “home-ec project” than a stretch stitch, which looks closer to store bought finishes. On the other hand, the stretch stitch is harder to seam rip than a long, narrow zig-zag stitch.
Some machines also do a triple stitch, which can look like thick topstitching. It places three stitches side by side next to each other before advancing forward. And in my experience this is the hardest type of stitch to use and the one most likely to make a hole in your fabric. Just because of the high number of stitches in a small area, it has the potential to pull your fabric into the throat plate. It’s also very hard to seam rip because of the high number of stitches. Proceed with caution if you decide to use a triple stitch.
Another stretch stitch you can do on a regular machine is a twin needle stitch. And instead of a long discussion of that, I actually have an entire post about twin needle stitching here.
The best way to figure out the best stretch stitch for your project is to use scrap fabric from your project and experiment with it.
Using a Serger and Overlock Stitch or Cover Stitch Machine
While you can sew knits with a regular sewing machine, I’m not going to pretend that specialty machines aren’t useful. Both a serger (also know as an overlocker) and cover stitch machines can be very handy for stretch sewing. In fact I use my serger for the vast majority of knit sewing.
As a side note, you can get an overcasting presser foot to simulate on a regular sewing machine the overlock stitch that a serger does. It’s an OK option, but as it only uses 2 threads instead of the 3-4 that a serger uses, it’s not quite the same.
An overlock stitch (made by a serger) has thread looped around the edge of the fabric. It also trims your seam allowances, so a serger is useful for woven fabrics as well to finish seams. Because of these loops, the stitch is very stretchy. However, because a serger cuts the edge of the fabric, it can only be used on seams, not for topstitching. So it’s not useful for hemming. (Unless you’re doing a flatlock stitch, which is another discussion and not always the sturdiest stitch).
Hemming is where a cover stitch machine shines. Some sergers even convert to cover stitching. On the top, it does what looks like a straight stitch, but instead of a bobbin it has a looper kind of like a serger for the wrong side. Which again makes the stitch super stretchy. And it doesn’t cut the fabric, so it can be used for hemming and topstitching. A twin needle stitch can get close, but it’s not as stretchy as a cover stitch, which is why most ready to wear knits are finished on a cover stitch machine.
Most cover stitch machines can even do a chain stitch, which looks like a regular straight stitch on the right side, but has a series of loops on the wrong side. This kind of stitch, when properly secured, is both stretchy and strong. This is also the type of stitch that used to be used on the tops of dog food bags, where you could pull the string and rip out the whole stitch easily. Because it can be easily ripped out, a chain stitch can also be handy to baste.
So there you go – depending on your machine, you have lots of choices when sewing knits!
Want to read more about sewing with knits? See these posts: