While a serger can make sewing knits easy, it isn’t a necessity. With a few pointers, knits can definitely be sewn on a traditional sewing machine. Successful results can be obtained on all kinds of knit fabrics – from stable knits like Ponte Roma to drapey knits like ITY and rayon jersey, to high stretch knits like swim fabrics. Sewing knits on a sewing machine doesn’t have to be intimidating!
1. Use a ballpoint needle
The first thing to remember when sewing knits on a sewing machine is to use a ballpoint needle. Ballpoint needles are made for use with knits. Their rounded tips push through the knit fibers, whereas a sharp needle could cut the delicate knit yarns. Choose the size of the ballpoint needle according to the weight of the knit you are sewing, using a lighter weight needle like a size 65/9 or 70/10 for lighter weight knits, an 80/12 for moderate weight knits, etc.
2. Try a twin needle
When hemming knits, a good (but not necessary) option is a twin needle; a ball-point twin needle is available in different sizes and can produce a very professional looking hem on knits. The twin needle also has the added benefit of creating a hem that stretches, so there won’t be the worry of popped stitches. Twin needles work best on medium to heavier knits, since lighter weight knits have the tendency to bunch and cause a tunnel-like appearance. Finding the best settings to use with it takes a little bit of practice, though, so be sure to test it out on scrap pieces of your fabric first.
2. Use a stitch that stretches
When sewing knits, we want the stitches we make to stretch along with the fabric we are using. Several stitches will give us this result. A narrow zig-zag to achieve this, with a width set between 1.5-2.5mm, can have quite a bit of give. When sewing with negative ease, as in swimwear, you can add a second row of zig-zag stitching to provide a little “insurance” against popped stitches! Another option is to use the stretch stitch setting on your machine. This stitch uses a lot more thread and punctures more holes into the fabric, though, so may be best saved for dense and more stable knits. If used on a tissue weight or thin knit like an ITY, it could stretch or damage the delicate fabric.
3. Use a longer stitch length
A longer stitch length has more give and will help your seams give more as well! Whereas we might use a stitch length of 2.5 on a lightweight, non-stretch woven, a stitch length of 3-3.5mm may give you better results when sewing knits.
4. Consider using a helpful foot attachment
One tool that I really like using for almost all my machine sewing, but especially knits, is a teflon sewing machine foot. The teflon just glides across all fabrics like a dream, and I don’t have to worry about fabric bunching up under the foot. Also, it can be purchased for a minimal amount of money, so giving it a try isn’t too big of a financial investment! Some people like using a walking foot when sewing knits. I have tried both on my Singer sewing machine, and while I have been happy with the help it provides on fabrics such as minky or vinyl, I have not found it to be necessary. Also, a walking foot is a little pricier than a teflon foot. With either foot, be sure to buy one that works with your sewing machine.
5. Start your stitches with a piece of tissue paper
A common mishap with sewing knits is that at the beginning of your seam, the feed dogs can have a hard time gripping the fabric in order to move it forward. Also common is the feed dogs can pull the fabric under the needle plate. Neither one of these is an ideal situation, and the latter can cause a big, bunched mess of fabric and thread, sometimes even tearing a hole in your fabric. One solution is to put a small piece of tissue paper under the first inch of your fabric. Leave an inch or two hanging out in back of the fabric in order to give you something to gently guide your fabric through the first few stitches. This also prevents the feed dogs from pulling your fabric under!
6. Avoid pulling or forcing the knit fabric through the machine
Knits need special handling at the machine. Always allow the feed dogs to do the pulling – don’t pull the fabric from the back or you’ll risk stretching it. Also, when sewing large pieces of knit fabric, always support the weight of the fabric that hasn’t gone through the feed dogs yet. If you allow it to hang without support, it can also stretch the fabric and leave you with a wavy seam.
7. Test your stitches on your fabric
It is always a good idea to test your stitches and settings on your fabric! This is the time to test out different stitch types, needles, feet and threads to see which gives you the best result. Following this step can save your fabric and also save a lot of seam-ripping time from your project! Don’t be tempted to skip it!
8. Press and stabilize hems
When hemming knits on your machine, press the hem first. Many knits can benefit from the added step of using a wash-away tape. Wash away tape is truly a lifesaver when it comes to hemming lightweight or drapey knits. The product is a little 1/4″ tape that comes in a roll. You first press your hem, then use the tape to hold the hem in place instead of using pins. It works like double-sided tape, just stick in place, peel the backing off, and press the other side of the hem in place. The tape stays in the seam and washes out in the laundry!
9. Don’t backstitch at the ends of seams
An alternative to backstitching at the start and end of your seams is to reduce the stitch length to a very short length, like 0.5-1.3 mm, for a few stitches. This will stop your seam from opening without the risk of being pulled into the feed dogs the way that can sometimes happen with backstitching.
10. For extremely stretchy knits, use a stretch needle
A stretch needle is made for sewing with lycra knits and is the best choice when using extremely stretchy knits like swimwear fabric. To determine if it is needed, test out your ballpoint needle, and if your machine is skipping stitches, a stretch needle may be your best bet.
11. For extremely stretchy knits, use stretch thread in the bobbin
Another helpful tool when sewing lycra knits is wooly nylon, or stretch thread. These types of thread cost a little more than multi-purpose thread, but are worth it for the added stretch they offer! Wooly nylon is available from multiple manufacturers. Maxilock makes a stretch thread, and it is made of textured nylon as well. It’s yarn-like appearance and texture allow it to stretch and can be used in the bobbin of a regular sewing machine. An important note: be sure to wind the bobbin by hand to preserve the stretch in the thread for your seams! Many sewists have had success sewing with wooly nylon in the bobbin even using a regular straight stitch on knits due to the added stretch from the stretch or wooly nylon bobbin thread. You can experiment to see which stitch works best for your project!