How to Sew Jersey Fabrics on a Domestic Sewing Machine – Part 1: Seams

Many sewers both new and experienced are unnecessarily scared of sewing stretch knit fabrics.

Most knit-phobes believe these popular myths about sewing knits:

1. I need to use an overlocker to sew knit fabrics
2. I can’t sew knit fabrics on my sewing machine
3. knit fabrics are harder to sew than delicate silk fabrics
4. knit fabrics have to be stretched when I sew them
5. it’s hard to cut out knit fabrics accurately
6. I won’t be able to get seams to match accurately using knit fabrics
7. it’s difficult to buy nice knit fabrics
8. I don’t want to make really tight figure hugging clothes.

None of these statements are true!  Let’s go through them again and tell you the truth:

1. No, you don’t need to have an overlocker to sew knit fabrics.  You can and an overlocker will make the job quicker, easier and neater, but if you’ve never used an overlocker before, definitely don’t start on one with a knit fabric!
2. All reasonably modern sewing machines have a selection of stitches specifically designed for stretch knit fabrics.  I’m going to show you the best ones for joining seams in this article.  Even if your machine only does straight stitch and zig-zag a narrow zig-zag stitch will do the job.
3. Some knit fabrics can be a bit more difficult to handle than a standard woven fabric, especially the lighter weight ones, but even a lightweight jersey isn’t going to be as difficult as a slippery lightweight silk.  A few more pins when cutting out and a bit of tacking when you might just have pinned are the only extra steps you’ll need.
4. I’ve actually seen this recommended in some of the bigger commercial pattern brand’s pattern instructions.  This is absolutely the last thing to do unless you’re after stretched wavy seams!
5. When cutting stretch knits you need to make sure the fabric isn’t hanging off your table because it will stretch the fabric, resulting in pattern pieces that ping up a lot shorter once you’ve cut them out!  If you don’t have room for the whole length of fabric on your table, pile it up over the back of a chair beside the table. Also use a few more pins than you might do normally to hold your pattern pieces accurately in place.  Using a few weights (or tins of beans!) to hold your pattern in place while you pin it will also help.
6. To match seams accurately pin them first and if necessary tack them. Also use the nature of the fabric to your advantage…..it stretches, which means it’s very forgiving if something doesn’t quite match perfectly and you can get away with a bit of stretching to fit (as long as that bit of stretch is spread out along the whole of the seam).
7. Have a read of my previous blog post about where to buy stretch knit fabrics, the different types of stretch knit fabrics available and their uses – knit fabric is a broad category.
8. You can make some really flattering, draped styles using stretch knits.  They’re not just for leotards and leggings!  Think about the clothes you own that you enjoy wearing…..I’ll bet a lot of them are made from knit fabrics.

So, hopefully I’ve made a start at converting you and you’re willing to have a try.  The first thing I’ll show you is some stitches to use for seams.  I’ll go through hems and finishing edges in separate posts.

NEEDLES

The first thing you need for any machine is:

a pack of jersey or ballpoint needles.  They’re a bit more blunt on the end than a regular sewing needle meaning that they won’t ladder the knitted structure of the fabric.  You can see they also come in different sizes like regular sewing needles.

Here’s a guide for which size will best suit which fabric:

70 – very lightweight silk or viscose jersey

80 – light t-shirt weight cotton jersey

90 – interlock, ponte roma, some cut and sew knits.

MACHINE SETTINGS FOR SEAMS

The first and easiest stitch to use for seams is the stretch straight stitch:

This stitch is useful when sewing with thicker knits whose edges don’t need any neatening and where you need to be able to press your seam open.

A stitch we use a lot for sewing knit fabrics in my classes is the overlock stitch:

This stitch mimics an overlock stitch and can join the seam and neaten the edges in one go.  You can trim off the excess seam allowance close to the stitching as shown in the second picture.  The seam then has to be pressed flat to one side rather than open, so it’s not suitable for more bulky fabrics.  It works well on most t-shirt weight jerseys.

The final stitch for seams is the narrow overlock stitch used with an overcasting or overlock foot.  (See this blog post for more about what an overcasting foot is and how to use it).

Here’s the machine with the overcasting foot attached.

This stitch again joins the seam and neatens the edge of the seam allowance in one go.  By also using the overcasting foot it means you don’t need to then trim off the excess seam allowance after sewing.  It also means though that you can only use it on narrow seam allowances (the overall width of the stitch).  It’s another stitch that results in a seam that has to be pressed to one side and gives a nice neat finish to lightweight jersey fabrics.  It’s not suited to heavier and thicker knits.

PRESSER FOOT PRESSURE

If your sewing machine has the ability to adjust the presser foot pressure, this can be helpful when sewing some knit fabrics to stop them being stretched by the machine as you sew.  You can read more about how to adjust the presser foot pressure in this blog post.

TENSION

As with all sewing, make sure the tension on your machine is set at the right level for the fabric you’re sewing.  If your machine’s tension dial goes up to 9, 4 should be fine for joining two layers of most medium weight woven fabrics.  A lower number means a looser stitch which you need for lighter weight fabric or fewer layers.  A higher number means a tighter stitch which you need for thicker fabrics or more layers.  You shouldn’t need to adjust the tension up or down by more than one number, meaning you will usually stay within the range of 3-5.

Most lighter weight knit fabrics eg. t-shirt jersey and lighter need a looser tension of around 3.

So there you are – how to sew seams in a range of knitted fabrics on your sewing machine.  I hope you’re turning from a knit-phobe into a knit-fan!  In my next article I’ll show you how to get nice hem finishes on knit fabrics using a sewing machine.

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