T-shirts, sportswear and other commercial garments made from knit fabrics are generally finished using a cover stitch machine. While you can purchase a cover stitch machine for home use, Holly Willis shows you how to achieve the same finished look using a standard sewing machine.
Cover stitch
A cover stitch is a double line of stitching on the right side and on the wrong side it looks like several zig-zags. This stitch stretches slightly, making it the ideal finish for knit fabrics. A cover stitch, rather than a straight stitch, is used on any area of a garment that will be stretched or stressed, as a straight stitch will most likely break. It is good to have knowledge of knit vs woven fabric in order to know what kind of seam finishes are best to use.
Twin Needle
Having proper sewing needle knowledge and knowing about the different types of sewing needles available can help make sewing projects easier. Holly demonstrates how to achieve the look of a cover stitch using a twin needle on a conventional machine. A twin needle, sometimes referred to as a double needle, is two needles attached on one shank. Twin needles come in various sizes, much like single needles, and are labeled on the needle package. There will be several sizes indicated, one is the needle size and one is the distance between the two needles. Twin needles can be spaced anywhere from 2 to 6 mm apart. When using a twin needle, ensure both the presser foot and throat plate of the machine have a large enough opening for the twin needle.
Threading
When using a twin needle to create a mock cover stitch, two spools of thread will be needed. Holly shows you how to thread your machine for using a twin needle and gives you tips on how to ensure the thread does not become tangled or twisted.
Stitching
Once the machine has been set up and threaded, Holly shows how easy it is to create the look of a cover stitch. She shows how to measure and fold under the edge to be stitched and how to line the raw edge up along the center of the twin needle. She then demonstrates how to ensure your fabric stays lined up while stitching.
I have done a cover stitch on many projects. I have found that I frequently get a seam that does not lay flat when using a double needle. It feels like the thread tension is too tight and causes a puckered seam. I cannot get the seam to lay flat, especially if I am sewing on lightweight knit fabric, and even though I make adjustments to the tension. What suggestions do you have for me?
Hello,
To avoid getting puckering or tunneling on your seam when using a twin needle, here are a couple things you can try:
Increase the stitch length slightly (However, keep in mind the more you increase the stitch length, the less stretch will be built into the seam.)
Use a layer of lightweight stabilizer behind the seam (For lightweight knits, I particularly like the Extremely Fine Fusible Stay Tapes from Emma Seabrooke (https://emmaseabrooke.com/product-category/tapes/) .)
Make sure your double needle is not dull by changing it out to a fresh one.
This forum (https://sewing.patternreview.com/SewingDiscussions/topic/91944) has a lot of great ideas from other sewists as to how to solve this problem, as well.
Hope this helps!
Best,
Nicki
This is a excellent tutorial and very easy to follow. Your filming technique is one of the best I’ve ever seen. I’ve been sewing for over 60 years and have been using twin needles for a long time in order to hem knits, it works beautifully and the only important difference between using twin needles on a standard machine is that a cover stitch machine is much faster. But I don’t mind the speed difference, it beats the cost of a cover stitch! Because I use a variety of machines, both modern and vintage, I hope you don’t mind if I offer a few suggestions:
A. Certain machines require a slight variation in how you thread it. If it does, you’ll find the information in the manual. I have a Brother quilting machine on which right-side thread must be set just a little differently, and it also has a specific setting for twin needles. If I forget to activate this setting, yuck! It makes a mess. Then I have a little old Kenmore 158-1040 that doesn’t care – run those threads through and off she goes, working like a dream.
B. I often thread separately because my old eyes don’t always work well enough to keep the threads separate as I do it. But that’s just me.
C. On some machines, I’ve found that it works best if the upper tension is loosened slightly. This of course, will vary from machine to machine.
D. Lastly, do NOT stretch your fabric as you stitch it. You’ll end up with a sloppy looking waviness that you won’t like. Just let the machine do it’s thing without pushing or pulling.
Good day, the sewing team,
I ‘ve read through all comments but still unsure. What stitch do I use? Regular straight stitch or straight stretch or something else altogether?
Thank you for your help,
Marianna
Hello Marianna,
Thank you for contacting us. 
You use a regular straight stitch to create the mock cover stitch using the double needle. The bobbin thread makes a zigzag on the wrong side, which builds stretch into the seam.
If you have any other questions, please chat, email, or call Customer Service. 
Sincerely,
Sarah
National Sewing Circle Video Membership
Hello there, I would like to know what’s the name of the thicker fabric used in the demonstration. Thanks, Ileana
Hello Lleana,
Thank you for contacting us.
This is a medium weight knit fabric, similar to sweatshirt fabric.
If you have any other concerns, please contact us at 1-855-208-7187, or chat with us on our site.
We greatly appreciate your business!
Sincerely,
Lindsay
National Sewing Circle Video Membership
Why is my thread getting shredded in my bobbin area. I’m at a 3.5 stitch length.
HA HA I had not threaded it all the way (half way through my threading the machine) 😛
I did exactly what this video said, however, my bottom stitch came out really tight and was NOT at all a zig zag. Do I have to literally take the bobbin out and loosen the tension with that little screw?
Hi, Sharon. You should not have to loosed the bobbin tension. I would recommend consulting your machine manual to see if your specific machine has a setting that needs to be changed before using a twin needle. Most do not, however there are some machines that do.
Hi, a different Laurie. When I got my first Pfaff, I was trying all the new stitches, including the double mock coverstitch. I was so disappointed when it came out with a tight stitch that had a pintuck, instead of lying flat. I realized I would have to loosen the bobbin tension and didn’t want to mess with my new machine that much. I got over it though. Still have that 1471 Pfaff and still use it. I am thinking of getting a new coverstitch machine, could live without it, another sewing machine, but would be handy. Good video. I do use an interfacing that was referred to me as “iron on jersey” it goes by other names. It has a shiny knit with a light stretch and has many uses for me besides this, but I use a 1inch wide strip all the way around on the raw edge, helps tame those pesky knits especially the super light ones. Also makes it easier to sew a nice looking hem. I always practice on my husbands discarded work T-shirts just to be sure whatever new technique for knits I find before I work on a customer item. Also now you can get narrow double sided tape which might help. I just prefer the quality of my hems when using iron on jersey.
So cool! Thank you so much for this! I have been doing two rows of loose stitches. I always wondered how to use a double needle. Can’t wait to try it!
I watched this twice because the fabric being sewn seems to be thicker than the piece it was cut from as well as white on the back. Is there a iron on backing for support? I sometimes use an iron on stretch jersey on flimsy knits.
Hi, Laurie. The fabric that she is showing when she first explains what stitch she will be teaching is not the fabric that the piece she sews is cut from, rather it is a t-shirt that she is using to show what the stitch will look like. The piece of fabric that she demonstrates the stitch on does not have any kind of backing. It is a sweater knit, sometimes called ‘sweatshirt fabric’ at some fabric stores, which is why the back is a lighter color.
wouldnt you use a stretch stitch for this hem?
Hi Elizabeth. The great thing about using a double needle for this technique is that it creates a stitch that can stretch with the fabric without having to make any modifications to the type of stitch you are doing.
Did you use the bobbin thread to thread the needle? Which sides of the needle go with which thread?
Hi Nancy. When you are using a double needle you will be sewing with two spools of thread on the top. No changes need to be made to the bobbin. Thread both threads through your machine just as you would if you were only using one, then at the needle, thread one through the right side needle and one through the left.
Hope this helps!
It would be helpful to mention which stitch type to use – you won’t get the back zigzag with just a conventional stitch. Not every machine is computerized as well…so you can’t just imput “mock cover stitch” and have at it.
Hi Diane. Thank you for your feedback. Your comments are important to us and we will forward your comments on to the proper department.
Does the mock coverstitch stretch?
Hi Cherie.
Yes, the mock cover stitch stretches slightly with the fabric.
Hope this helps!