Knit fabrics are great to wear and fun to sew with but they can be a little tricky to handle. I was intimidated by them for a long time but with a lot of practice and a few tricks I picked up along the way, I’ve been able to conquer those stretchy beasts. Today, I’m going to share my favorite method for topstitching knit fabrics plus some tips and insight on why knits can be so bothersome. And don't worry, you don't need a fancy machine, this can all be done on a conventional sewing machine.
TIP ONE: Feed your fabric.
The big difference between sewing knits and woven fabric is the stretch. A basic sewing machine does a great job of feeding your woven fabric under the needle but it can be challenging to feed a stretchy knit fabric. The fabric can bunch up, get stuck in the throat plate and the stitch length will be uneven and wobbly.
I have two methods for helping feed your fabric through a conventional machine. Option 1, use a walking foot (on left in photo above) when stitching knits. The walking foot has feed dogs on the top that help move the fabric evenly under the needle. Option 2, (if you don’t have a walking foot) place strips of tissue paper underneath your fabric as you stitch. When you’re done, gently tear the paper away. The paper creates a stable base for the fabric that the feed dogs can grab onto and push under the needle.
TIP TWO: Stitch with stretch
Your fabric is going to stretch as you wear it, so you want your stitches to stretch too. If the thread can't stretch, the stitching can break (you can actually hear a pop when this happens). To create a stretchy topstitch, use a twin needle or a zig zag stitch. The twin needle has two threads on the top and one on the bottom (the bobbin). The bobbin thread will be slightly stretched between the two top threads. I like to use wooly nylon (or fluff thread) in the bobbin. It’s a stretchy thread that will help your stitching lay flat. The zig zag stitch is also a great option for topstitching. It looks a little less professional than the twin needle but if your thread matches the fabric quite well you probably won't be able to see the stitching anyway. And sometimes the zig zag looks really cool.
USING A TWIN NEEDLE
My machine (Brother CS-6000i) has specific threading instructions for using a twin needle and I recommend reading your manual to make sure you do it the way your machine likes. I first tried a twin needle when I was in high school and I just couldn’t get it to work. I bet if I had read the manual (or if sewing blogs existed back then :) I would have been able to make it work. I was scared to do it again for a long time after that because it didn’t work just that one time. But I finally gave it another go, read the manual and now I love it.
A twin needle is the best way to get two lines of stitching that are perfectly spaced from each other. There are varying widths of twin needles so you can have a little fun and try different looks. Above you can see the 2mm on the left and a 4mm on the right. I really love the wider needle but if I'm topstitching a narrow seam allowance in place (like on a neckline) I prefer the narrower needle. The wide needle can end up topstitching with one needle on the seam allowance and one on the outside which then creates a ridge.
WOOLY NYLON THREAD
Discovering this thread was something of a revelation. The wooly nylon thread is a stretchy thread that's made up of multiple strands. I've read that it's often used when serging and with undergarments. So far I've only used it in the bobbin when topstitching and I totally love it. When using regular thread in the bobbin, the two top threads can pull together a little and create a ridge. The stretch of the wool nylon lets the two top threads lay flat. Yay! I have one spool in off white and one in black and that's so far worked well for any project.
Now that you have all the background you’re ready to topstitch your knits! You don’t need a fancy machine but I do recommend a few supplies. This method can be used on hems or to finish a neck or arm binding.
How to Topstitch Knit Fabric
2 spools regular thread (You don't need to buy to full spools of the regular, just wind up a bobbin with the regular thread to use as the second "spool.")
Wooly Nylon Thread (aka fluff thread)
Sewing Machine with Walking Foot
(or if you don’t have a walking foot, some strips of tissue paper as discussed above)
1. By hand, loosely wind wooly nylon thread around bobbin.
2. Attach walking foot to machine and insert twin needle. Thread machine according to your machine’s manual.
3. Set your machine to a straight stitch. (I like to use a 3.0 stitch length, just slightly longer than normal.)
4. If you are starting at the edge of the garment, place a strip of tissue paper under the garment with a tail hanging out the back. (This will help prevent the fabric being pushed down into the machine by the needle.) Place garment under needle, lower presser foot and stitch.
5. At end of stitching, raise presser foot, pinch garment at stitching line and pull away from the machine about 8 inches. Cut thread leaving a 4-5 inch tail. Gently pull the ends of the top threads to the wrong side and tie in a knot with bobbin thread. Trim ends. Repeat with threads at beginning of stitching. (This will secure the threads and create a clean look on the right side of the garment.)
I hope these tips will help you in your sewing adventures. And remember it's ok if your topstitching isn't perfect. Mine rarely is! If you want more info on sewing with knits I recommend a couple of books that have really helped me: Sew U Home Stretch by Wendy Mullin and The Colette Guide to Sewing Knits by Alyson Clair. Do you have any tips or tricks for stitching knits? Please share in the comments. Happy sewing!