The tricky thing about sewing knitwear is that the (most of) the stitches on a standard sewing machine won’t stretch enough to keep up with knit fabric.
So the best way to seam knits is with a machine called a serger. If you look at the side seams of nearly any t-shirt, you’ll see what a serger seam looks like.
I bought a serger many years ago as one of my plans to “learn sewing for real this time.” (I’ve tried to “learn sewing” ever since I was in my teens. I make a concerted effort every decade or so, to little success.) These days, I mostly use my serger to finish off the raw edges of handwoven fabric before washing it.
I plan to use my serger for underwear construction
However, there are very few seams in underwear. What there are are a lot of hems. The waist and leg holes are essentially three long hems.
There are ways to make a standard sewing machine make a stretchy stitch: use a zig-zag or serpentine stitch or a twin needle and (depending on the stretch of your fabric) you might get stitches that won’t bind or break.
For a truly stretchy hem, however, the tool to have is a coverstitch machine. Turn up the hem of your t-shirt, you’ll a coverstitch hem.
I’d recently sold a loom, and putting the proceeds towards a coverstitch, trading one machine for another, seemed a worthwhile thing to do.
The first coverstitch machine I was interested in was a Babylock Coverstitch. Unfortunately, they’d just discontinued that model and none of the local stores had any left. Not wanting to risk learning on a used machine (how would I know if problems were me or the machine?) I asked what the new model from Babylock was.
“It’ll sew through anything,” the sewing machine saleswoman told me over the phone. “It’s all-metal construction.”
“It’s the size of a small car,” I said, looking at the Babylock website, and then at my modestly-sized sewing table.
“It sews like a dream, you’ll never regret it. And it’s on sale… ”
It was the pandemic, so I bought it without trying it out beforehand. (Something I do not, in general, recommend.)
What I came home with was the Babylock Euphoria. It is huge, it does only one thing, and it does it very, very well.
Only…now I had to learn how to use a coverstitch machine!
YouTube came to the rescue: GingerHead and Co. and The Last Stitch have some great coverstitch videos. Johanna Lundström from The Last Stitch has a book, Master the Coverstitch Machine, that I am strongly considering buying. I’ve already found at least one of her offhand tips to have made the difference between fail and success with wooly-nylon thread.
And yet, I was intimidated. I didn’t know what tension to set the needles or loopers at, what stitch length to use, or how it sewed… or anything.
However, I’d just given a seminar on using the scientific method for fiber arts. So I decided to follow my own advice and start by sampling, sampling, sampling.
I created ‘research samples’, with no intention of creating anything other than information I could use as a reference later. That way, regardless of the result, it would be a success, because I’d learn something.
In experimentation, it’s good to change as few variables as possible at one time, so I established some guidelines:
- 95% rayon, 5% lycra fabric at 6oz weight
- Fold-over elastic
- Wooly-nylon thread in the looper
Note: The fabric I used for sampling is from a chopped up shirt, which is why you see other seams on the samples.
I chose the rayon/lycra because it’s soft next to the skin and is one of the standard fabrics carried by Knitorious, a fabric printing collective that takes pre-orders for fun geeky fabrics, has them printed, and then sends them out to folks.
Fold-over elastic is one of the easiest way to finish off hems on underwear. I decided to start with this because (a) I had a ton of it, bought from a local fabric store that went out of business and (b) easy is good.
Wooly-nylon thread in the loopers is often used in underwear and swimwear because it’s a fibrous thread that “fluffs out” after it’s stitched and is known for being next-to-skin soft. I like soft, so it seemed a good thing to do.
Because beige is not a color I typically wear, I used up my beige fold-over elastic when I started my experimenting. Then I had the fun discovery that I could write on the light-colored fold-over elastic with a Sharpie pen, making the samples self-referencing. Yay!
The first few samples I tried were scratchy, something I definitely did not want in the seams of my underwear.
I experimented (changing one machine setting at a time) until I came up with the idea of using a chain stitch (a single-needle-and-looper stitch that looks like a regular straight stitch on one side and a series of knit loops on the other.) Since fold-over elastic does not have raw edges, this should work fine!
The settings that seemed least scratchy were: SL 1.0, UT 0, LT 3, DF N
SL stands for stitch length, UT for upper (needle) tension, LT for lower (looper) tension, and DF for differential feed (and N means neutral).
It produced a chain stitch which still had a bit of a scratchy rib on one side. If I put that ridge on the outside of the underwear: problem solved!
Turns out that was not the best stitch to use, as I discovered several pairs of underwear later…