How to Sew Knit Fabrics: Sewing With Jersey 101
Babies love wearing cozy knits! Ladies love wearing cozy knits! The Season of Cozy is upon us, but when we asked the Prudent Mamas, we discovered everyone is nervous about knits. We get that! Since we have a bunch of cute patterns for knit jersey dresses and such planned for you, we thought we'd start by getting everyone comfortable with sewing knits. Let's start with a little primer, including what equipment you need (or don't need), the different stitches, and some basic tips to help you get on your way to Cozytown.
From the feedback on our facebook page and twitter, we see that the Prudent Mamas have concerns about stretched out seams, popping threads, and slippage while sewing. The overall conclusion was that knits are scary. No! Knits are just stretchy. Let's take the mystery out of sewing these stretchy beasts.
Then you can make these cute dresses I share a pattern and tutorial for here: Beginner's Jersey Baby Dress!
Learn the basics of how to sew with knit jersey fabrics after the jump...
How to Sew Knit Fabrics: Sewing With Jersey 101
First we'll talk about FABRIC, then GEAR, then STITCHING, and finally TIPS for sewing with knit jersey. Here we go...
Knit Fabric 101
There are ten trillion different knit fabrics out there. To understand the basic difference between cotton and knit, let's look at some diagrams. Cotton is woven:
Knits are, well, knitted (with loops):
(thanks for the illustrations, threads magazine)
There's single knits, double knits, and rib knits. Some look different on each side. Some look the same on both sides. Some stretch a lot. Some stretch a little. Some are blended with rayon or acetate or (as Scarlet calls it) "sparkle thread." Some are thick. Some are so thin you can see through them. There are so many fun options and you can sew them all! First you need to examine your fabric. Let us do so. Which way does it stretch? Stretch on the cut edges, then from the selvedges. One way will almost always stretch more. Make a note of it and cut the pattern as directed with the more stretch facing the right way. Sleeves are usually cut width wise (most stretch), same with shirt body. Some patterns are bias cut (on the diagonal) for a lovely drape.
In these pics I'm sewing with one of my husband's old hanes t-shirts, and with stretchy Robert Kaufman panda knit, which I absolutely adore. Don't you just want to snuggle up in it?
So now you've got your fabric. What else do you need to start sewing knits?
Knit & Jersey Sewing Gear 101
There is some gear that makes sewing knits much easier, but you don't need all of it to sew with jersey. Let's go through it and I'll tell you what's not absolutely necessary and what's a must-have.
A Cover Stitch Machine.
Hi, almost no one has one of these at home. I sure do want one though. A commercially sewn knit item usually has a hem with a double row of stitching. A coverstitch machine hems these up quick and neat in one step. But no worries, you can simulate this look with a regular sewing machine.
I adore my Brother 5234 PRW. If you have a serger you can thread all four needles, then sew your jersey and cut your seams at the same time. But NO, you do NOT need a serger to sew jersey.
Today we will focus on how to sew jersey with a sewing machine instead.
Here are some things that are affordable to get and will help you enormously when sewing knit jerseys.
A Twin Needle
Many machines come with a twin needle, or you can purchase one inexpensively.
If your machine can zig-zag it can usually accommodate a twin needle. The benefit of a twin needle is that it builds stretch into your seams by creating two lines of straight stitches on the top of your item with a zig zag underneath. No popped seams, no trying to precisely stretch your fabric as you sew. Let me show you really quickly how to thread a twin needle so you understand the concept. When you use a twin needle, you'll use two spools of thread on the top. Your machine probably comes with an extra spool pin that fits on top of the bobbin holder you normally use while winding bobbins, like this:
But even if you don't have an extra spool pin, you can jerry-rig it by placing the second spool of thread somewhere nearby (on a thread rack, in a cup) where it won't get tangled or resist unrolling while you sew. So once you've set up your spools, you'll run both threads through the machine as you normally would the one thread. You thread the needles manually, the left one with your normal spool, and the right one with the second spool. I did them in two colors so you could see (the normal spool is black, threaded through the left needle).
Then you use your zigzag foot while sewing.
A ballpoint needle has a slightly rounded tip that allows it to slip through the fibers of your fabric, rather than ripping them as a regular needle would. There are also stretch needles that have a deeper indentation (so the needle can create a longer thread loop before forming the stitch, decreasing the chance for a slipped stitch). I have never bothered to get stretch needles, but for a very delicate fabric I would. There are also universal needles that say they are for both woven and knit fabrics, but I have not tried them. Now, you may want to give sewing jersey a shot with a regular needle. You can try it out if you are desperate. On a stiff men's t-shirt (like your basic Hanes or what have you), a regular needle may work. But on a stretchy or delicate knit, it's going to create tiny tears in the fabric that will get worse as you wash and wear. So I say definitely get ballpoint needles.
Ballpoint is on the left, straight is on the right.
I like to sew knits with my walking foot, especially if they are very stretchy. A walking foot moves both the top and bottom layers of fabric at the same time. This makes it a lot easier to avoid stretching the fabric out too much. They run $15-20 and you'll use it a lot once you get one (for quilting and such). You can sew jersey without a walking foot, but it will take more trial and error with each new fabric to see how much you need to guide/stretch that specific fabric to avoid stretched seams. Here is what a walking foot looks like from the front:
And from the side:
Let's do a comparison. Here I am using my stretchy panda knit fabric. I used a ballpoint needle and stretch stitch (explanation of stretch stitch and the other stitches you can use for knits later in this post), and in this first pic I used a walking foot.
Looking good, laying flat. In this next pic I used all the same setting, but with a regular foot.
See the difference? A walking foot just makes it much easier to keep the seams from becoming stretchy and sloppy, especially with very stretchy fabrics.
I don't often use interfacing when sewing with jersey, but sometimes it helps to stabilize a seam that will get stretched/pulled during use (for example a shoulder seam). You don't want to use regular old interfacing, you want to find one for knits that is more flexible. Try to match it to your fabric's flex as close as you can. But for beginners, don't worry about interfacing just yet.
Stitches for Sewing with Knit Jersey Fabric
Ok, let's talk stitching.
As we've mentioned, knits and jerseys have varying degrees of stretch. If you just sew them together with a regular old straight stitch, then you have stretchy fabric with a not-stretchy seam. What do you think will happen when you stretch the fabric out? That's right, the seam will pop. Here's a pic of my panda knit stretch jersey with a straight stitch - I pulled on the fabric, check out how not-nice it looks...
One more pull and what do you think will happen?
That's right: It will pop right out. We don't want that to happen to our clothes, which should be able to move with us as we gallivant around town. So we don't want to use a straight stitch. I do want to be clear that you CAN use a straight stitch to sew knits, BUT it requires a certain skill because you have to stretch your fabric *justright* as you sew to ensure the straight stitch seam has the right amount of stretch built in. It is much easier to use one of the following stitches until you get more experienced or find your groove with knit sewing.
If you are sewing with a twin needle, you can use a straight stitch, since the twin needle straight stitch has stretch built in. Here's what that looks like on the front (the black is the left needle, the taupe is the right needle, just so you can see the difference):
And here is the back of the twin needle straight stitch, with black thread in the bobbin:
That sure looks nice. But if you don't have a twin needle, don't fear.
You can sew knits with one needle, no problem. Ideally, your machine has a stretch stitch. Which one is the stretch stitch? It is the one that looks like an offset zig zag. This stitch goes forward, then back a bit, to create a seam that can stretch with your fabric. Here is a pic of the stretch stitch diagram on my machine, it's #4. I call it the lightning bolt.
Stitch #3 is a triple stretch stitch, especially good for armholes or other areas that take a lot of abuse and may need more strength built in.
If you don't have a stretch stitch, no fear. A narrow zig zag stitch will do the trick. Set the width and length very low (2.5/.5 is a good starting point) and test it on your fabric scraps to find the best setting to make sure it lays flat. The zig zag will allow your fabric to stretch.
Here is a pic of all three stitches on a basic heavy knit mens tee, just so you can see what they look like. The heavy mens' t can take a lot of stitches without doing anything too funky when it's just one layer like this, but when you start to sew two pieces together, they stretch pretty easily, just an FYI. The stitches from right to left are stretch, zig zag, straight.
Whichever stitch you choose, test it out on some scraps of your fabric and adjust the tension as necessary until your stitching lays flat. It gets fancier from here, with stretch blind hem stitches and what not, but we'll stick to these basics for now. Ok, on to the sewing of knits...
Sewing Knit Jersey Fabric
A lot of your work with knits is going to involve some amount of trial and error, so always buy a little extra fabric and do some tests. I'll share some tips to help you have less error as you are doing your trials.
Beware the Stretch
If you are using your walking foot and a stitch with stretch, then you want to be sure you are not stretching your fabric out as you sew. If you do you will end up with floppy seams and stretched out armholes and the like. Let's look at an example on my stretch jersey fabric. I used my walking foot, ballpoint needle, and stretch stitch. The stitch settings are exactly the same in both rows, but on the top row I let the fabric stretch as it went through the machine, while on the bottom row I was careful not to let the fabric stretch.
See the difference? So watch out for stretching while feeding your fabric through your machine.
Let's talk about sewing two pieces of fabric together to create a seam. This example uses cut up remnants of my husband's old hanes t-shirt sewn with a ballpoint needle, walking foot, and stretch stitch. In this first picture, I was careful not to stretch the fabric as it went through the machine:
Looking good! In this second picture, I was not careful and the fabric stretched just a bit. Now look at my seam:
A walking foot and being careful not to stretch your fabric too much are the two best ways to avoid these gaping seams. There is more to this when it comes to finishing necklines, but I will save that for another post while we all practice a bit first.
Finishing Inside Seams
Jersey will not unravel, so you do not need to do anything to finish inside seams except cut them even. However, if you have a serger it does add nice polish to your item to serge the seams, before or after you construct the piece (I usually do it before, but that's just personal preference). If you are sewing with a thick fabric, a seam allowance from 1/2" to 5/8" is fine. If you are sewing with a thin/delicate knit fabric, the edges will roll, in which case you want to sew (or cut down) to a very small allowance, because the fabric has a tendency to curl and a big curl can be uncomfortable to whomever is wearing the item.
You can hem your item the traditional way, but you only need to fold under once, since the edge of the fabric won't unravel (this also reduces bulk at hems) and stitch in place (or just roll under and stitch if the fabric is very thin).
The only issue is that you will have a zig zag or stretch stitch hem, which doesn't always look very awesome. This is a great time to whip out your twin needle, so you can have straight seams with stretch built in. You can also sew with a straight stitch if you think you can stretch your fabric just the right amount to have a stretchy hem that won't break. Or if you are making a dress or skirt, where the hem is unlikely to get stretched out while it is being worn, you can risk a non-stretch straight stitch. Or you can just cut that baby, because as I said, it won't unravel.
Serging a rolled hem is also fun if you can. Or if you are fancy, go ahead and do a stretch blind hem stitch or some such awesomeness.
From here, I am going to share some patterns and tutorials that will allow you to practice all of these skills and learn about finishing necks and armholes, so they look polished like this (it's so not hard at all I promise):
as well as adding sleeves
gathering, and other fun things you can do with jersey.
A good starter project that you can play around with right now is Jacinda's adorable (and super giftable) Top Knot Baby Hat, which comes in three different versions and can be made from recycled tees. It'll give you a good sense of your machine and knits, and you'll get the satisfaction of a completed project of adorableness.
Okay Prudent Mamas, I hope I addressed a lot of your concerns, and took some of the scare and mystery out of sewing with knits.. Let me know if you have any questions about what I've shared here, and I'll add to this post or follow up with more information. I hope this helps you feel a little less intimidated by knit jersey and encourages you to cut up some old clothes and get crafty. Stay tuned for our first jersey dress project and pattern later this week!
Update: Get the pattern and tutorial here: Beginner's Jersey Baby Dress!