tutorial: sewing knitwear using (mock-)serge stitch

Here is a self-drafted top I made Phoenix, yesterday afternoon. It took me about a half hour. I particularly love the marriage of fabrics, both very soft cottons:

The day before, I made this in a different colorway of the same Michael Miller clown stripe line:

Despite their simple construction, knitwear – as in leggings, t-shirts, and undergarments – can be rather difficult for the beginning stitcher. Yet most machines have good knit functionality. If you’ve a sewing machine less than thirty years old or so, chances are it includes stretch stitches. These are scary-looking stitch settings many new and intermediate stitchers don’t mess with:

On my Pfaff, you can see them in the 20-range:

20 through 29 are easily what one would hear called stretch stitches; however, ten through 19 can qualify too. Why? It’s simple. If you think about a stretch stitch, its job is to stretch along with the garment as strain is applied to the seam (think: pulling a hooded sweatshirt over one’s head). A straight lockstitch would pop. But almost anything that has some zigzag can stretch with the fabric, then recover. If it is a version of a straight stitch that meanders, like Program 19, or doubles back on itself, the resultant seam might be sturdy enough to withstand seam strain without stretching much or at all.

But it’s a little more complex than that. Knowing whether the seams will need to stretch or not is key. Some stretch garments are made with so much wearing ease that you don’t need a very elastic seam. Take, for example, the Kwik Sew knit cardigan pattern below. First, imagine you have a pin-sized head and large 80’s-esque shoulders and hair fashion. Then, think of how little strain these garment seams endure – for instance, you could easily make this garment in a drapey woven fabric and not utilize stretch fabrics at all:

In contrast, imagine wearing a swimsuit and how much strain the stitches are subjected to while you wear it. And finally: different seams in a garment need different behaviors. The side-seams in a loose-fit crewneck t-shirt won’t likely need to be very elastic, whereas the neckline will definitely need this capability!

Therefore: when it comes to sewing knits, experience is the best teacher. Sewing is after all a three-dimensional, structural, form of engineering!

Recently I’ve enjoyed sewing with stretch stitches, as opposed to my oft-used narrow zigzag, for a few reasons. Here’s my list of considerations to use stretch stitches, or to avoid them:

Possible Benefits

1. These stitches make a sturdy, good-looking seam. You can sew and finish the garment in one step, using one spool of thread and bobbin.

2. If you cut accurately and practice, you won’t have to do any trimming after you sew. You will end up with a lovely finished garment with very good-looking inner seams. If you love sewing, chances are you love good-looking seam finishes.

3. Mastering these stitches means you don’t have to invest the time and space of a serger or even a coverstitch machine. There are lots of good reasons to own these pieces of equipment, but there are also reasons to be able to do without them.

Possible Disadvantages

1. These stitches use more thread than a zigzag (but not more than a serger); this means more thread cost, more wear on your needle and machine, and more lint. However, even an entire shirt won’t eat a whole bobbin’s worth of thread.

2. These stitches take longer to stitch than a zigzag. If you’re used to “whipping through” a garment (a phrase I loathe, by the way), it might take a bit to get used to a slower stitch pace.

3. These stitches can stretch the fabric in unbecoming ways, which is why you will read people complaining online about knitwear ending up “wonky”. Yes, this can happen – UNLESS YOU KNOW MY AWESOMESAUCE TRICKS to avoid this [she said, triumphantly]! Read on:

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Let me walk you through sewing up a couple of tops. I used two stitches – Program 20 (which was referred to as the “closed overlockstitch” in my manual) and Program 12, a double-zigzag (more in a bit, on that stitch).

Supplies

1. A proper needle (stretch, ballpoint, or jersey) and polyester or polyester-core thread
2. Your sewing machine manual. I PITY THE FOOL who sews without one! I don’t even.
3. Water-soluble stabilizer. This stuff is worth its weight in gold for sewing with knits and it is the BASIS OF MY TRICKSY-est TIP in this tutorial. Buy some at your local sewing shop or buy it online. As you sew you will have all these strips married to the garment seams and it will look assy. But when you wash the garment, they will disappear and you are left with coolness. (Tangentially: using stabilizer is also how I add woven or knit appliques to knit fabrics, even thin and stretchy knits).
4. Your garment pieces, cut out with about 1/4″ seam allowance

Directions

1. Make sure you have a good needle, inserted properly, and that the machine is threaded and tension-balanced.

2. Cut strips of water-soluble stabilizer into 1″ widths. Over time you will get the hang of how much to cut per garment, although I use these strips so much I have a bunch of them in my supplies. Obviously, for the most part, you are cutting the same length as the seams you’re sewing, so you can do a rough pattern-edge measurement.

3. Start sewing, feeding the water soluble stabilizer under each seam. Take special care starting and finishing the seams. Knits are so fast to sew, so make the time to get a secure sleeve hem, et cetera. Here you see me at the end of the seam, using the overlockstitch (Program 20) and a width of 4.5 mm (a very scant 1/4″):

The glowing green lights are buttons I have engaged: the left button is “Needle Down” (meaning when I release the foot pedal, the machine will stop with the needle in the fabric – very handy) and the right is “Reverse”, as I’m about to back up the seam to secure it. Upon the “Reverse” button, my Pfaff performs the stitch pattern in reverse unlike my Juki, which merely stitches a small straight stitch backwards. I like securing the HELL out of my seams at the beginning and end, yes even if I am going to cross this stitchline with another seam later. Please note: using your sewing machine provides you with a better seam-securing backstitch option than most sergers:

4. I am using Program 20 for these construction seams. I used them to make the whole garment, including fastening the hood to the neckline. However, for the hood’s face edge, I used a double-zigzag. Here you can see it after I finish it on the machine, then from the RS of the garment after the stabilizer has been washed out, then the WS:

This stitch (#12 on my Pfaff Program, see above photo of my machine) is identical to a triple-zigzag except it only ‘bites’ two stitches while travelling in the zig or the zag. I like the way this zigzag looks and it is a great, stretchy, sturdy seam. Please note, if you have to apply elastic to a garment, as in the top of the hood or ruching, triple-zigzag is BAWSE.

For this simple black-and-white striped hoodie, the only real complexity is the two-layered sleeves and attaching the hood at the neck.

Let’s talk necklines first. I love using the overlockstitch for necklines. It is super-simple, easy to secure at the beginning and end of the stitching line, and only takes one simple step whether you’re attaching a hood, a band, a turtleneck, whatever. Check it out on the self-bound neckline of the orange-and-raspberry shirt:

By the way if you’re thinking I OWNED aligning stripes on these shirts, you’re right!

Now: sleeves. Specifically, two layered seams. You can sew the sleeves into tubes and apply them, or apply them simultaneously in the flat, as I did. I simply pinned at the edges of the seams and at the shoulder (three pins per sleeve) and sewed slowly. What’s the rush? You’re almost done with the shirt already!

Remember your stabilizer! You will be glad you did, when you wash the stuff out and your shirt drapes beautifully. Check out these seam finishes, too:

What about hems? What about them? I hardly ever do them for knits. An unhemmed sleeve and garment edge looks great and feels great. If you insist on making them, use a stretch twin needle and more stabilizer, or some form of stretch-stitch and stabilizer. For a slim-fitting garment like this, you’ll want a hem that has a little give.

Now: enjoy your super-soft knit garments LIKE A SIR