There’s lots of stuff that can go wrong when you hem a lightweight knit on a sewing machine.

Knits, especially lightweight knits, get stretched out of shape far too easily, and it’s common for thin knits to get caught under the throat plate of a sewing machine.

And then when you finally get thread into the fabric, stitching on stretchy knits often is puckered or uneven or creates unsightly “tunnels.” What’s more, because ready-to-wear knit clothes are ubiquitous — hello, cheap AND comfy — eyeballs can spot a *slightly* wonky me-made T-shirt in a blink.

Don’t fear, knit sewist! There is hope.

With careful finishes, patient techniques, and the right tools, it’s possible to sew handmade — not homemade — lightweight knit garments that make you feel accomplished and look fashionable.

This article is split into three info-packed chunks:

  1. Tools: Gear I own that I’ve found useful when sewing lightweight knits
  1. Top tips: Two things to keep in your head before you start sewing a hem
  1. Stitches: Which stitches give you the best results

P.S. Read until the end to find out how you can get practice sewing slinky, thin knits. I got you!

This post features affiliate links chosen for you. If you click through and make a purchase, I may receive a commission at no additional cost to you. Affiliate advertising is the main way I earn income from Sie Macht, and I thank you for your support! 💙


RELATED: What Does Weight of Fabric Mean?


Tools for Sewing Hems on Lightweight Knit Fabrics

My love of sewing supplies is well documented on this website, so it should come as no surprise that I’ve got a WHOLE buncha stuff for sewing knits.

The notions and whatnot I’m going to talk about in the tools section can be used in combination OR solo. It’s entirely up to you, based on your unique fabric, sewing machine, and, honestly, mood that day.

For example, even though it does a great job with knits, my walking foot isn’t used a lot because I’m usually too lazy to switch out my presser foot. (Just being honest.) It’s a good tool that delivers great results, but… most days I’m confident I can get what I want (or close to it) without it.

OK, with that caveat, here are my top tools to have in a lightweight-knits-sewing toolbox (in no particular order).

Duckbill Scissors

This also is called an applique scissors. If you’re cutting two layers of fabric, the funny shape keeps you from cutting the bottom layer (it kinda pushes it away). The scissors are good for trimming down hem allowances after a hem is sewn.

Starch

Want to fake a fabric that’s easy to sew? Spritz some spray starch on a thin knit to add body. The starch washes out and you’re left with a well-sewn hem.

Fusible Web for Knits

There are a few versions of this type of product. For this article, I used Heat n Bond Lite Soft Stretch fusible web adhesive.

The idea is that you press up your hem, slide a strip of fusible in the turned up bit, glue it all together with your iron, and stitch the hem in place. Many sewists on the internet like using fusible tape on knit hems because the tape gives them a crisper hem with more body.

Wooly nylon thread and stretch-fabric-specific fusible web.

Lightweight Paper

This tool kinda gives me the heebie-jeebies, but I’ll suggest it anyway. If sewing a lightweight fabric is going sideways for you — tangles, poor tension, snags — you can try putting a piece of THIN (e.g., tissue, tracing, wrapping) paper between the feed dogs and the fabric as you sew.

The paper will help move the fabric under the needle in a way that doesn’t make you feel murdery. Once stitching is done, you pick the paper off the bottom of the fabric.

The paper trick makes me uncomfortable, because I don’t like putting non-fabric stuff in my sewing machine. I worry that paper will jack up something internally. (A sewing machine is a finely calibrated machine!)

I’ve changed my tune a bit, though, on using paper because I recently noticed that my very own sewing machine manual recommended this trick! So, check YOUR manual, do a little research about the risks (if you’re risk averse like ME), and choose your choice. Lots of sewists use this trick.

Walking Foot

The feed dogs and presser foot of a sewing machine move at *slightly* different rates. In my experience, the feed dogs are faster.

When you use a walking foot, the presser foot and feed dogs move AT THE SAME SPEED, which means the layers of fabric underneath the presser foot (theoretically) stay even. Use a presser foot slowly for best results.

Should you be interested, before I had a serger, I tested different combos of needles, presser feet, and upper thread tension to figure out the best configuration for sewing knits with a sewing machine. The walking foot played a critical role in success.


RELATED: Beginner Serger Supplies: What You Need for a New Serger


Correct Sewing Machine Needle

If you’re sewing with knits, you MUST use a ball point, jersey, or stretch needle. These types of needles pass through the knits and purls of a knit fabric instead of breaking the yarn. Passing through = stretchy properties remain intact.

And you’ll want a small needle — probably size 70/10 or 75/11 — for a slinky, delicate knit. A needle that’s too large will mash down the fabric.

When I’m having trouble sewing lightweight knits, the first thing I check is the needle. Sometimes, even if you know the needle is fresh out of the package, ya gotta swap it for a different one. Why? Who the heck knows, guys.

Iron and Press Cloth

To coerce a naughty knit into the proper shape for a tidy hem, give the hem a press BEFORE you sew it. This gives the fabric a “memory” and makes it easier to sew.

It’s REALLY easy to overdo pressing with a lightweight knit, and when you go too hard, you can melt the spandex in the fabric and create shiny spots and/or stretch the fabric into an undesirable shape. I’ve done both.

To avoid this, I suggest:

  • Using a low temperature
  • Using a press cloth
  • Pressing on the wrong side (to better hide shiny spots)
  • Using up-and-down movements more than side-to-side movements with your iron
  • Not lingering in any place
  • Using a clapper to set those folds (vs. the potentially damaging heat, weight, and steam of an iron)

Be gentle. Tiptoe with the iron; don’t stomp and drag your feet.

Basting

You can baste hems by hand (with a running stitch) or use a long straight stitch on your machine. Sometimes this is preferable to gobs of pins. Don’t sleep on basting; it’s like taking a practice test before the real exam.

Washable Glue Stick

When I sewed a swimsuit, I discovered that washable glue stick was the best basting tool ever. It adds a little body and nicely holds together layers of thin fabric.

Wooly Nylon Thread

Wooly nylon thread is fluffy. It’s not plies of thread tightly wrapped into a single yarn (like an all-purpose poly thread). Because there’s no tightness to it, this floofy nylon thread has more give, which is what you want in knit garments.

To use fuzzy nylon thread in your sewing machine, wind it BY HAND onto a bobbin. Remember, the remarkable characteristic of wooly nylon is its flexibility, and it can’t be flexible if it is wound too tight.


RELATED: How Do I Choose a Knit Fabric?


My Top 2 Tips for Hemming Stretchy Fabric

Before we examine stitches, here are two things to keep in mind when you sit in front of your machine, ready to make your first stitch:

1.) Be Gentle

The most important thing to remember when sewing lightweight knits is to use a gentle touch. Let the sewing machine, presser foot, and feed dogs do the work of moving the fabric. Avoid pulling at all costs. Because when you rage against the machine, it’s the fabric that suffers.

And when your fabric looks like it’s been chewed up and spit out, that’s a dead giveaway for a homemade T-shirt. (And we want better than that, right? RIGHT.)

2.) Be Critical

Take a hard look at the hem. If the hem doesn’t need to stretch — i.e., it fits over/around the body without need of expansion or compression — you don’t necessarily need a stretch stitch. (For example, the hem of a knit circle skirt doesn’t need to stretch.)

But, if you don’t use a stretch stitch, the stitches are more likely to break. And, if a non-stretch stitch IS expanded but DOESN’T break, it can be stretched out and end up looking baggy/wavy and lose the tension that keeps the stitch balanced in the fabric.

Best Hem Stitches for Thin Knit Fabric

Before I could declare which stitches result in the most successful hems for slinky knits, I needed to decide which stitches to test.

I looked through my sewing manual and picked stitches that have:

  • A lateral (side-to-side) component to create slack (and stretchability)
  • Little (or no) backward movement, because lightweight knits don’t have enough stability for multiple stitches in the same location

The fabric used in the stitch samples is a bamboo-rayon knit — very drapey, bouncy, and lightweight. (Should you be interested, the fabric is featured in an article comparing knits vs. wovens.)

Unless otherwise noted, all the stitches share the following in common:

Without further ado, here are the best sewing machine hems for lightweight knit fabrics.

Classic zig-zag back. With many fold-and-stitch hems on knit fabrics, you can cut away the extra allowance.
Classic zig-zag front.

Classic Zig-Zag

  • 3.5 mm width/3.0 mm length
  • Used Heat n Bond Lite Soft Stretch fusible web adhesive

It’s a tidy zig-zag stitch — not too big, not too small. Longer stitches generally are better with lightweight knits. There’s not enough body in these fabrics to support shorter, more satin-like stitches.

Long and skinny triple zig-zag back.
Long and skinny triple zig-zag front.

Long and Skinny Triple Zig-Zag

  • 3.0 mm width/4.0 mm length
  • Used Heat n Bond Lite Soft Stretch fusible web adhesive

This stitch has a decorative vibe to it. The lightweight fabric moves smoothly under the presser foot and doesn’t get jammed up; the feed dogs like this stitch-fabric combo. Because it’s a three-part stitch, it’s strong.

Serpentine stitch back.
Serpentine stitch front.

Serpentine

  • 7.0 mm width/3.0 mm length
  • Used Heat n Bond Lite Soft Stretch fusible web adhesive

The serpentine stitch looks a bit like the triple zig-zag, but its waves are spaced farther apart. This is a cool stitch that should get more play!

Fagoting back. The top has no fusible web; the bottom has fusible web. The bottom stitches have slightly more tension, because the fusible web gave the hem slightly more body.
Fagoting front. The top sample has no fusible web, and the fabric shifted/stretched a bit more under the stitches vs. no fusible web; you can see the stretch in the grain.

Fagoting

  • 7.0 mm width/4.0 mm length
  • Used Heat n Bond Lite Soft Stretch fusible web adhesive

Fagoting is definitely a decorative stitch. It has a wheat-slash-crosshatch-sort-of look. I think this would be good in a contrasting OR matching thread; a matching thread could give a tone-on-tone lewk.

Shell tuck back.
Shell tuck front.

Shell Tuck

  • 7.0 mm width/2.5 mm length
  • Upper thread tension: 3

You make the shell tuck stitch on the EDGE of the hem fold. The needle goes off the fabric to make the lateral stitch. I tried the stitch with fusible web, but it made the fold and decorative “shell” shapes too stiff and straight.

Stretch blind hem back.
Upper thread of blind hem stitch from the back. You can see where the thread takes a tiny “bite” (at the point of the triangles) out of the fold to secure the hem.
Stretch blind hem front. The “bites” from the orange upper thread are invisible from the right side.

Stretch Blind Hem

  • Centered (0.0 mm width)/3.5 mm length
  • Blind hem presser foot

To sew the stretch blind hem, I starched the sample rectangle to give it more body. I also placed a piece of tracing paper under the single layer of fabric (see middle photo above with orange upper thread) to help move it smoothly under the presser foot.

Woven bias tape back.
Woven bias tape front.

Woven Bias Tape

  • Zig-zag stitch: 1.5 mm width/4 mm length
  • Woven bias strip, folded in half

Yes, you can finish a knit garment with woven bias tape. It’s a SLIGHTLY stretch finish, and it adds weight to the hem. I could see it being especially good for a skirt hem, where a little extra mass at the bottom could be nice, or a curved hem. Here’s a photographed tutorial about how to finish a knit with woven bias tape.

Straight stitch with twin needle back.
Straight stitch with twin needle front.

Straight Stitch with Twin Needle

  • Schmetz stretch twin needle, size 4,0/75
  • Centered (0 width)/3.5 length
  • Used Heat n Bond Lite Soft Stretch fusible web adhesive
  • Upper thread tension: 6

Ah yes, the fake coverstitch — straight on the top and zig-zagged on the bottom for stretchiness. I use a thread stand for twin needle sewing; that link goes to a post about my experiments to find the best twin needle sewing setup.

Final Thoughts on Hemming Thin Knits

I PROMISE you can get a profesh-looking hem on a thin knit with a sewing machine. The No. 1 thing when facing this challenge is to sew with tenderness. That means sew slower than you think and never bully the fabric. Don’t pull, and don’t stretch. Let it glide.

With a little practice, some testing, and a gentle touch, you, too, can stitch knit hems without trepidation!

Cass T-shirt call to action

And, I’d like to help you get some practice. You’re invited to check out Sie Macht’s Cass T-shirt, which is designed for lightweight, drapey knits. It’s a relaxed-fit T that accommodates busts up to 66 inches and hips up to 70 inches.

Get your free Cass PDF pattern and get hemming! And if you want more content around Cass, here ya go:

Over to you: What’s your favorite way to hem knits? How do you feel about fusible web such as Heat n Bond? Please sound off in comments! Thanks for reading.