We have lots of knit patterns at Closet Core and we can't imagine a wardrobe without them! Undies, t-shirts, sweats and jumpsuits... there are so many garments you can make once you get some experience under your belt. While the principles of sewing knits are similar to sewing wovens, there are a few tricks that will make your experience a little smoother. From prepping your fabric to setting up your machine, a few key adjustments when sewing knits can make all the difference. If knits are totally new to you, start with this blog post on understanding knit fabrics to get started on the right track!
Choosing Knits by Weight, Fibre + Stretch
When choosing a knit fabric for a project, the most important elements are fibre, weight and amount of stretch. When it comes to weight, you need to take into consideration the silhouette of the pattern. Is it a drapey dress you want to hang and cling to your body (like our Ebony dress)? Or are you looking for something with some structure that can hold the shape of a balloon sleeve (like our Marigold Sweater)? In general, thicker, heavier knits will give you more volume and shape, while a thinner knit will give you a softer drape.
Various fibres will also respond differently. Something like 100% cotton jersey will drape and move much differently than a rayon/spandex jersey, which has much more stretch and drape.
Direction of Greatest Stretch
When it comes to stretch, most knits fall into the category of two-way stretch or four-way stretch. This means that the fabric stretches in either one direction (ie. along the cross-grain) or in two directions (along both the cross and lengthwise grain). In general, most fabrics stretch the most horizontally across the cross-grain (from selvage to selvage) but you should always check your fabric first. We've definitely encountered two-way stretch fabrics where the stretch runs vertically or parallel to the grainline. This is why it's so important to always find the Direction of Greatest Stretch when you're working with knits.
DOGS or Direction of Greatest Stretch refers to the direction in which your fabric can stretch the most, and a well-drafted pattern (especially if it calls for any negative ease) will indicate which direction the DOGS should run in. If called for, make sure to align the DOGS arrow on the pattern piece with the DOGS of the fabric. Otherwise, if you're making a close fitting knit, try to ensure the direction with the most stretch of the fabric goes around the body (rather than up and down).
With that said, our Marigold sweater flips the script on this convention - we wanted to take advantage of the drape of DOGS, so we direct you to cut your pattern pieces in a different direction than what is typically required. For that reason, please refer to the instructions before laying out your pattern!
It's always a good idea to wash your fabric before a project to remove any chemical sizing, but it's especially important with knits. Knits have a tendency to shrink in slightly unpredictable ways, so make sure to wash and dry your fabric in whatever manner you will be caring for your finished garment. Nothing like pulling a brand new pair of sweatpants out of the dryer to find it now fits your kid (true story).
- If your fabric is shifty use lots of pattern weights and a rotary cutter.
- Cut on a single layer for maximum control. Don't forget to mirror pieces when cutting two.
- If your fabric starts curling up at the edges you can try spraying it with some fabric starch. Spritz it on and bake it in with a press from the iron. It will come out in the wash but will give you more control when sewing your seams.
- Grainline can be be tricky to find with knits. The best tip is to fold your fabric in half and match your selvages. Pick your fabric up by holding the selvages together - If the fabric is off-grain, you'll see rippling along the fold of the fabric where it's hanging. Shift one side of the fabric selvage over until the fold is smooth and flat. Your fabric should now be on-grain.
Setting Up Your Machine
SERGER + OVERLOCKER
The easiest way to sew knits is with a serger. When used with all four threads, you build mechanical stretch into your seams while finishing them at the same time. Most sergers will have settings, especially for knits and you can experiment with which stitch setup you like the look of best. Be sure to turn on "differential feed" - this ensures both layers of knit get pulled through evenly. If you are experiencing wavy, stretched-out seams with your serger, you probably have not engaged the differential feed.
COVER STITCH MACHINE
A cover stitch machine is just for finishing and creates beautiful hems and topstitching, particularly for knits. If you are going for the professional look of ready-to-wear and you sew a lot of knits, this machine is an excellent investment.
You don't really need a special machine for knits. With the right fabric and a little know-how you can tackle most knit projects with a regular sewing machine. Refer to this chart for stitch lengths and types that are suited to various types of seams.
Always choose a jersey or ballpoint needle for sewing knits, as regular needles often result in skipped needles. The dull rounded tip slips between the knit fibres rather than through them and will generally give you a smoother line of stitches. This will also protect the fabric from getting pulls or tears and will leave less noticeable holes if (perish forbid!) you have to rip anything out. You can also try a stretch needle if using fabrics with spandex like swimwear or performance fabrics.
It's important to note you still need to pay attention to the numbers when using any stretch needles. 70s are designed for lightweight knits like diablo or silk jerseys, 80s are perfect for viscose and interlock and 90s will work for heavy things like scuba or Ponte.
Twin or Double Needles
If you want the professional look of a cover stitch machine without the actual machine, consider a double needle. Twin needles are just what they sound like, two needles that share one shank. They give you the super polished look of RTW knits with two even rows of topstitching on top, connected with a zig-zag stitch below for stretch and mobility. They are probably the lowest buy-in for the biggest value, giving you that professional look without any expensive machine upgrade.
Try a Specialty Foot
If you're having a hard time getting perfectly smooth seams or if you are using a heavier knit you might want to try a walking foot (also called an even foot.) Knit fabrics can sometimes start to stretch and shift as you sew them— 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 the layers feeding through the machine at the same rate so your seams stay even and smooth. They are especially handy for matching stripes!
Sewing Tips for Knits
- Use fine pins to avoid putting large holes in your fabric. These ones are super fine and perfect for delicate knits.
- To avoid your fabric getting eaten by your machine, hang onto the thread tails with your left hand when you start sewing. Gently pull them as you begin sewing to keep those curly edges from crawling into your needle plate. You may also want to start your stitching a little further in rather than starting super close to the edge of the fabric.
- Make sure you don't stretch your fabric when sewing seams. Let your machine feed the fabric, holding it flat as it goes under the needle. Stretching knits as you sew them stretch out your seams, creating wavy seams or gathering.
- Use high-quality polyester thread. The slight stretch in polyester makes your seams stronger and is less likely to break or skip stitches.
- To make high-stress seams hold up longer, sew a piece of clear elastic into the seam line. Shoulder seams especially will benefit from the extra support.
Trouble Shooting Wavy Seams
- Try sewing a piece of tissue paper in between layers of fabric. This can help stabilize the seam while you sew it. You can rip it out after.
- If the layers of fabric are shifting too much as you sew, try basting them by hand before you sew. This ensures the best, most stable results.
- Never underestimate the power of heat and steam. Wavy seams will often flatten and shrink back to size when exposed to a little steam (make sure to test when using synthetic fibres).
- Reduce the presser foot pressure if you're able to with your machine - this will help your machine feed the fabric without stretching it.
- Try using the differential feed on your serger. Sergers have two sets of feed dogs (top and bottom) and you can adjust the speed of both to help correct any tension issues causing waves.
Now go and sew all the stretchy things!!
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