Knits are one of the most comfortable fabrics to sew into garments, but their seemingly mysterious ways can frustrate a someone who’s new to sewing. This complete beginner’s guide to sewing with knit fabrics will demystify them and allow you to successfully finish any project.
We’ll start with with an overview of of knit fabrics and wrap up troubleshooting tips. Along the way, this post will answer your questions and guide you through a complete project.
What is a knit fabric?
When it comes to fabric, you generally have two options: wovens or knits.
Woven fabrics are, as you might guess, woven on a loom, with vertical and horizontal threads (called the warp and the weft). Knit fabrics, on the other hand, are knitted, meaning the fabric is made up of interlocking loops.
How can I tell if a fabric is knit?
Unlike most woven fabrics, a knit fabric will stretch when pulled. Some stretch side to side, giving you a two-way stretch. You can also find a four-way stretch fabric that has side-to-side as well as up-and-down stretch. Knit fabrics are comfortable to wear and easy to fit because they will stretch over the wearer.
How do I know which knit fabric to use?
There are many weights of knit fabrics, and each stretches a different amount. They also each have their own drape.
A good tip is to look in your closet and find a favorite knit garment that feels, stretches and drapes the way you’d like — then check the label and write down the type of fabric it uses. Find this fabric type and weight at your local fabric shop or online. You could even take the garment with you to compare the feel of it in person.
Tip: If you’re a beginner knit sewer, it is best to choose a heavier knit with less stretch. It will be easier to sew and will give you practice and a win on your first projects.
Do I need a special sewing machine to sew knits?
Your regular sewing will do the trick! You’ll need to make sure you’re using the right needles, presser foot and stitch settings. Keep reading to get all the details!
Some more experienced sewers choose to use a special machine called a serger or coverstitch machine for sewing knits. These machines create stitches that stretch with the fabric. While a serger certainly makes sewing with knits a bit easier, it’s far from necessary, especially for beginners.
Which needle should I use for sewing knit fabric?
A ballpoint sewing machine needle (also called jersey needles) is essential for successfully sewing knit fabric. These needles are available in your local shops and online in many types and weights.
Unlike a sharp regular machine needle, ballpoint needles have a dull tip. The needle’s point slides through the knit weave, allowing the threads to stay together. A regular machine needle will cut through the knit fabric and you will soon have tiny holes along your seam line.
What other tools and notions do I need to sew knits?
Consider using an even foot or a walking foot.
This foot (two names for the same thing) feeds the top and bottom layers of fabric through the machine evenly.
The stretch in knit fabrics can cause the layers to separate as you sew — especially if you are stitching in the same direction as the fabric’s stretch. A walking foot has an extra set of feed dogs for the top layer of fabric that work with the bottom feed dogs in your sewing machine to help keep everything in place.
Try sewing with a twin needle.
A twin needle stitches a seam that will stretch and move with the wearer. Despite its unusual look, a twin needle is easy to use and readily available. The needle uses two threads to create two lines of stitching on the top of the fabric with one thread in a zigzag pattern, connecting them on the back.
Tip: As a bonus, twin needle seams look more professional, mirroring the look of a hem or top-stitched seam on a knit ready-to-wear garment. They are available in many different widths.
Clear elastic can help stabilize your seams.
Turn a favorite ready-made tee inside out and you are likely to see clear elastic stitched into the shoulder seam. This specialized elastic stabilizes the seam and helps to keep it from drooping with wear. It is simple to use and can be sewn directly into the seam wherever you want less stretch.
Try fusible knit hemming tape.
Hemming with fusible knit hemming tape is like magic, especially if you encounter trouble with wavy seams on your knit garments. Once this tape is fused to the raw fabric edge, the fabric is stabilized with less stretch and you can proceed to stitch the seam as usual.
How do I prepare to sew knit fabric?
Pre-shrink your fabric.
Before cutting out a garment, it is always important to pre-wash the fabric. This will pre-shrink it so the garment will stay the size you need after future washing. Knits can shrink in unpredictable ways, even when the label indicates that they have been pre-shrunk.
Note the stretch amount.
Before choosing a pattern size, take note of how much your knit fabric stretches. Each type of knit fabric is different, and this will greatly affect the fit of your finished project. Most patterns suggest which knits will work best, and some will include a stretch gauge so you can predict how the garment will fit once it is sewn.
Find the direction of stretch.
When cutting out a knit using a pattern piece, you must always note the direction the fabric stretches most. Usually, the direction of most stretch will need to go around the body, not up and down. Your pattern pieces should indicate the correct stretch direction. Line up the pattern piece parallel to the stretch direction carefully before cutting.
How do I set up my machine to sew knit fabric?
Use a stretch stitch.
Knit garments are made to stretch and fit over the body — and this means the seams must also stretch to fit.
Most sewing machines come preprogrammed with one or more stitches made especially for knits. These are called stretch stitches. Your sewing machine manual will tell you which one to use for heavier or lighter weight knits. Stitches 4 – 12 in the photo above are stretch stitches included with my Janome 2030 QDC.
If you do not have a specific stretch stitch, you can set your machine to sew a long, narrow zigzag (pictured above.) This works best on areas of the garment that need to stretch a lot, like necklines and armbands.
Tip: You may also have good luck sewing a very long straight stitch, especially when you are sewing against the direction of most stretch, such as a side seam or loose fitting hem.
Use your feed dogs.
The feed dogs on your machine feed the fabric through evenly. When sewing a knit fabric, it’s important to let the fabric feed itself under the presser foot without pulling the fabric. If a knit is stretched while sewing, it will generally stay stretched after it is sewn as well. This creates an undesirable and unprofessional finish.
Sew a test run.
Layer small scraps of your knit, just as they would be when you are sewing your garment. This is usually two layers, but you can also test a hem or topstitch with three or more layers.
Stitch using your chosen stretch stitch following the direction of stretch you will use on your garment. Test a few stitches until you are happy with the results. This little test can save you a lot of trouble and lots of time unpicking a troublesome seam!
How can I fix a wavy seam?
Press with an iron.
A wavy seam will benefit greatly from a good press. This is different from ironing, where you move the iron back and forth over the fabric.
To press the wavy seam properly, first lay it out flat on an ironing surface. Then place the hot iron on the seam and leave it for a few seconds without moving it around. Lift the iron straight up and move on to another section of your seam. Leave the garment in place until the fabric has cooled for best results.
Change the presser foot pressure.
Many machines allow you to lessen the pressure of the presser foot. This will help the top layer of fabric to slide through more quickly and evenly. Check your manual to find instructions for your specific machine. Sometimes it also helps to “release the pressure” on your fabric every few inches by raising and lowering the presser foot in place while the needle is down.
Tip: Remember to reset the pressure before you sew your next project!
Try the tissue paper trick.
If you’ve tried all of the above ideas and your machine is still causing wavy seams, here’s another trick you can try! Cut a 1″ wide piece of tissue paper (the kind you wrap gifts with) and place it over the top layer of fabric. Stitch the seam as you would normally, right through the tissue paper. The tissue paper layer slides differently under the presser foot and the fabric will not be able to stretch as much.
Tear off the tissue paper once the seam is sewn, being careful not to pull the threads too much. Try placing tissue paper above and underneath the layers of lighter weight knits, especially on unruly hems.
I’m inspired to sew!
Knits are a joy to work with and will expand your ability to create useful wearable garments. As with most skills, practice is key. No matter what sewing machine you have, there are tips and hacks available to help your journey proceed with success. You can find more tips for sewing with knit fabrics and more about the Soleil Dress on my blog.