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Sergers & Overlockers

8 Serger / Overlocker Stitches Explained Simply (+ Photos)

If you’ve ever looked at a serger listing online (also called an overlocker), you’ve probably been confused by all the stitches it can do!

Like a “flatlock”.

What is it? What does it look like? When would you use it in the real world?!

So what types of stitches can a serger do? Here are the main ones:

  • 4 and 3 thread overlock = used to create seams and stop fraying.
  • 2 thread overlock = a lightweight stitch used to finish the edges of lightweight fabrics.
  • Rolled hem & narrow hem = finish the edge of a single layer of fabric.
  • Mock flatlock = join 2 pieces of fabric with a flat seam. Often seen on shop-bought sportswear. A serger can’t do the real thing, just a decorative stitch that looks similar.
  • Blind hem = Finish your hems with this “invisible” stitch (in my experience, it’s difficult to make it invisible).
  • Picot edge = a decorative way to finish the edge of a single layer of fabric.

(Note: a “seam” is a line of stitching that joins 2+ layers of fabric together).

Most people only use the overlock stitch, and maybe the rolled/narrow hem.

They often don’t know the other stitches a serger can do.

Today I’m going to show you close-up photos of 8 serger stitches.

I’ll explain what they do in more detail, when to use them, and the pros and cons of each.

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overlock serger stitches

Contents list:

Related article: How to Choose a Serger or Overlocker: 21 Factors to Consider (+ Checklist)


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Overlock stitches

This is the main stitch you buy a serger for.

  • It joins 2+ pieces of fabric together to create a seam.
  • It can be used for knits (stretchy fabric) and wovens (non-stretchy fabric).
  • An overlock stitch can stretch! So when you’re sewing knit fabrics, your overlocked seam won’t break when stretched.
  • It finishes the raw edge of fabric to stop fraying, so your finished item will last longer.
  • You’ll often see this stitch in shop-bought clothes and textiles.

All sergers can do 3 or 4 thread overlock stitches.

Only mid-range and high-end sergers can do a 2 thread overlock.

4 thread overlock stitch

4 thread overlock stitch

Pros

  • Use 4 threads when you need a strong seam.
  • The 4th thread acts as a “back-up” line of stitching. This means you’re less likely to get a hole in your finished project.

Cons

  • Because it uses more threads, it creates a bulkier seam.

3 thread overlock stitch

3 thread wide overlock serger stitch
Note: the looper threads (red & blue) should be tighter here. We don’t want the loops hanging off the edge.

Pros

  • Use 3 threads when you just want to finish the raw edges of a seam.

When you’ve already made a line of stitching on your sewing machine, you don’t need a strong overlock stitch. You just want to stop fraying.

  • If you’re making an item that won’t be put under much stress, like a loose-fitting t-shirt, you can use a 3 thread overlock to create seams too.

2 thread overlock stitch

2 thread wide overlock serger stitch

Pros

  • This is a nice way to finish lightweight fabrics. It uses fewer threads, making it a lighter and finer stitch.

Cons

  • This isn’t normally strong enough to create a seam. It’s for finishing raw edges only.
  • I rarely see budget sergers that can do 2 thread stitches. You normally have to buy a more expensive machine for it.

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Rolled hem

rolled hem on a serger / overlocker

It folds the edge of the fabric under, then wraps it in threads.

This stitch looks really “full”, which is beautiful.

Here’s how to use it in the real world:

  • Finish the edges of a silk scarf.
  • Finish the hem of a bridesmaid/prom dress made from chiffon or tulle.
  • Finish the edge of a ruffle.

Pros

  • This is a beautiful way to finish the edge of a single layer of fabric. The aim is to stop fraying. It’s not used to create seams.
  • It works best on lightweight fabrics.

Cons

  • It uses a lot of thread, so it’s bulky.
  • Because the stitches are so close together, it takes longer to sew.

Narrow hem

narrow hem on a serger / overlocker

Like the rolled hem, the serger folds the edge of the fabric and wraps it in stitches.

So what’s the difference between them?

They look different.

A narrow hem has a “line” running along the edge of the fabric (where the blue and red threads meet). It also has more gaps between each stitch.

Pros

  • Like the rolled hem, this is used to stop the raw edges of one layer of fabric fraying.
  • It works best on lightweight fabrics.
  • Use it to finish the edges of ruffles, napkins, and scarves.

Cons

  • It tends to have a less “full” look, so you’ll get more gaps between each stitch.

For this reason, if you’re working with a fabric that frays a lot, I would choose the rolled hem over the narrow hem.


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Mock flatlock stitch

flatlock stitch on a serger / overlocker
The front and back of a flatlock stitch on woven fabric. Here 2 pieces of white cotton were joined with a flat seam.
close-up of a flatlock stitch made by a serger

This joins 2 pieces of fabric without creating a seam allowance that sticks out.

It creates a flat seam.

Pros

  • It’s popular in sportswear. You don’t want a seam allowance rubbing against your skin during exercise. It might cause chafing. So a flat seam is more comfortable.
  • Amy Alan, a serger teacher, recommends this stitch when you want to join thick layers of fleece. A flat seam is great here because it reduces bulk.

Cons

  • Unfortunately, a domestic serger can’t make the real flatlock stitch seen in shops. That’s a much more complex stitch.
  • We can create something similar looking, but don’t expect it to have as much strength. According to manufacturer Pfaff, it’s more of a decorative stitch.

I gave my flatlock sample (pictured above) a good tug and was surprised it could handle it. So it’s not a completely weak stitch.


Blind hem stitch

blind hem stitch on white cotton fabric
The blind hem on a woven fabric. Not pretty! The yellow stitches should be even. However, this was the best sample I had after a lot of trial and error. Serging a blind hem is tricky.
serger blind hem on stretchy grey fabric
A blind hem on a stretchy fabric.

Pros

I normally always hem on my sewing machine.

However, technically you can sew blind hems on a serger.

  • You can hem a dress or trousers made from woven fabric.
  • You can hem a stretchy t-shirt.

Note: no settings for knit fabrics were in my manual. So you’ll have to do a lot of experimentation!

You want the hem to stretch with your fabric, so making sure your needle thread isn’t too tight is important.

Cons

  • Serger manufacturers normally boast it creates an invisible hem, but in my experience, it’s not easy to achieve this!
  • It creates a much bulkier hem than a sewing machine. That’s because it uses a lot more threads.
  • You’ll need a special foot to do this stitch. It’s called the blindstitch foot. It’s included with many sergers, but not all.

So I personally don’t love this stitch. It’s tricky to sew and uses a lot more thread than a sewing machine.


Picot edge stitch

[image coming soon!]

This is a decorative way to finish the edge of 1 layer of fabric.

The serger folds the edge of the fabric, then wraps it in threads.


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