Creative articles about sewing

Which thread do you use in an overlocker?

When you’re about to start with an overlocker, the question arises: Which thread do you use for your project? Of course, you can choose a thread color that matches your fabric. But did you know that there are also different types of threads for your overlocker?

When I first started using the BERNINA L 460, I wasn’t sure where to begin with thread. I used a thread from Mettler that I had lying around on large cones. While searching for a new thread color, I discovered that there’s not just one type of overlock thread available.

Image of BERNINA L 460.


The BERNINA overlocker L 460 offers up to 1500 stitches per minute and ensures beautiful and flexible stitches. The BERNINA L 460 is the perfect overlocker/serger for the creative sewer of knitwear.

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It was high time to find out what’s available and what kind of thread to use when in an overlocker.

In this blog post, I’ll discuss the three types of threads I most commonly came across when searching for overlocker threads: universal thread, thin shiny thread, and fluffy thread.

These types of threads are available in various brands and qualities. I got to choose some threads from Mettler to test. In their range, I found the three different types of threads that I’ll discuss in this blog: Seracor, Seralene and Seraflock.

Types of Threads

Of course, there are more than three types of threads that you can use in an overlocker. And for each type of thread, there are various variations in composition, thickness, and other properties. However, these three types of threads are the main categories I encountered most frequently. And they are also the types of threads I’m most likely to use in my projects.

Universal Thread

When you search for ‘overlock thread’, this is what you’ll come across. Polyester thread, on large spools, in many different colors. This thread is available in many different price ranges and qualities. I’ve been using Mettler’s Seracor for a while for sewing other (quilt) projects. I’ve also quilted quilts with it on the BERNINA Q16.

So, this was the thread that went on my overlocker first because I had it lying around. And this thread works great on the many projects I’ve made with jersey fabric. The thread is not super thick or super thin, it doesn’t have a high sheen. It’s a very nice universal thread.

The thread is suitable for different types of fabric. I’ve used it a lot on jersey fabric in children’s clothing, and it works very nicely.

Thin Shiny Thread

This category might have a specific name (please let me know in the comments!), but I think ‘thin shiny thread’ sums it up nicely. By this, I mean the thread that is so beautifully smooth and thin that it almost falls off the spool when you’ve released the starting end. It’s very suitable when working with thin fabrics.

What immediately struck me after sewing with this thread, after sewing with the universal thread, is that it’s a lot thinner. It feels smoother and more supple. And because it’s thinner, especially when sewing with a matching thread color, it will hardly be noticeable. This thread is very suitable for thinner, smoother fabrics.

Wooly Thread

This fuller thread is also called ‘Wooly nylon’. It’s a loose thread that opens up a bit when you look at it up close. It’s used for elastic seams in underwear and swimwear but is also very nice for a rolled hem.

What I learned about Wooly Nylon, or mousse thread, is that it doesn’t go into the needles of your machine. For a regular sewing machine, it goes in the bobbin. And for an overlocker, this thread goes into the loopers. So, you only need two spools if you want to try this thread.

This thread is soft. And that’s immediately the reason why I’ll definitely use this thread more often when sewing jersey children’s clothing. The entire seam feels cuddly and soft. Especially for a tank top or summer dress where the seams are against the skin, this thread will feel nicer than universal thread.

Summing Up

When you hold the seams next to each other, the differences become clear. Here you see the thin shiny thread at the top, the universal overlock thread in the middle, and the fluffy thread at the bottom.

Rolled Hem

The thread from the last category, the fluffy/mousse thread, is also very suitable for making a rolled hem. This thread fills the hem more than universal thread or the thin shiny thread. Below you can see a comparison of the three types of threads in a rolled hem.

At the top, you see the fluffy thread, in the middle, the universal thread, and at the bottom, the thin shiny thread.

In a real project, you would, of course, use a matching color for a rolled hem. Then such a rolled hem will look even nicer.

In the close-up below, you can clearly see the difference between universal thread and fluffy thread. The fluffy thread spreads out, filling the space between the stitches nicely.


It’s fun to try out the different types of threads. With the same stitches, the same machine settings on the same fabric. This makes the differences between the threads clear.

For my jersey projects, I will definitely continue to use universal thread as it goes well with that. But for baby and certain children’s clothing, I’m now going to add fluffy thread to make the seams softer. And I’ll definitely keep fluffy thread nearby for rolled hems too.

What’s your favorite thread for the overlocker?

Until next time!

Difficulty level: Beginner
Time to Complete: Evening
Used Material: Cotton jersey, mettler seracor, Mettler Seraflock, Mettler Seralene
Used Products:

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  • Mary Teague EditEditing comments on the BERNINA blog is only possible after logging in with a blog user account. Sign up now or create a user account if you do not have one yet.

    I love Mettler thread, but I haven’t compared the types in this way. Your post and especially the photos are very helpful. Thank you!

  • Sabrina Kaindl EditEditing comments on the BERNINA blog is only possible after logging in with a blog user account. Sign up now or create a user account if you do not have one yet.

    Hello Irene, thank you for your blogpost. It was very helpful! Now I know what I can do with the fluffy thread I was gifted with. I started using an old overlocker of my mom shortly. For my childrens clothes and shirts for me. For a summer skirt with jersey-leggins underneath and sewn together I will try the fluffy thread, too. Normally I use universal thread on mini cones which I can use on the overlocker and for little seams on the sewing maschine, too. For example seams to put on a little bag in front of a hoodie. Love to read and view more of you – about sewing and quilting 😀 Greetings Sabrina 

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