Here are some of my ‘oh at last I understand that’ moments.

(‘Serger’ is the US name, ‘overlocker’ in the UK.)

After many years of incomprehension, I recently did feel I know enough about what is involved, and bought an overlocker myself. I’m not at all a ‘jump in and have a go’ person 😀
And now I have one I’m finding there’s much more you only learn by using one !

Choosing your machine
If you can, find an (on-line) manual for any serger/overlocker model you’re thinking of buying, or a video, and see how the loopers are threaded.

Most modern machines have threading aids, such as :
– coloured dots mark the threading path.
– ideally, during threading, a lever moves the lower looper so it is easier to get at – a machine with this aid may be more expensive. (Jaguar machines have the feature of fully opening up so you can get at both loopers easily.)
Beware product descriptions which say something like ‘self threading lower looper’. Look at the manual carefully, this phrase often means there’s some help with getting at the lower looper while threading, but there’s still much for you to do, including getting the thread through the final hole.
– check the instructions are easy to understand.
I got a machine which has particularly clear videos about looper threading : well lit and close focussed with good camera angles, a revelation ! Enlarged videos can even make it look easier than it is. There’s a lot crowded into a small area near the needle : upper and lower loopers, stitch finger, cutting blade.

It’s also good to have a machine on which you can adjust : stitch length, stitch width, presser foot pressure, and differential feed (see below). More expensive machines allow you to make a wider range of adjustments : more widths, more lengths, etc.

Air threading of the loopers may be much recommended for removing all threading problems, and most machine companies now have a model. These machines are not just ‘press a button and watch’. It’s only the last phase of the looper threading which is ‘automatic’. You do still have some input to the process, including threading the needles. These machines are about twice the price of other models, and I have heard that they are the type of machine most often brought in for repair.

Which thread does what ?

Here is a tutorial on the types of stitches, from Threads magazine.

This image (from that Threads post) shows the 4-thread stitch.
Used for seams on knits, seam finishes on wovens.

yellow – left needle
green – right needle
blue – upper looper (above fabric)
purple – lower looper (under fabric)
These are just the colours in these diagrams, there is no standard use of colours. My machine colours are red, yellow, green, blue. Even different models from the same brand may have the colours used differently !

Note the two sides of the stitching look different – the needle threads (yellow and green in the diagram) only show on the right side of the fabric. So if you want all your overlocking to look the same on a project, it all needs to be stitched from the same side of the fabric.

Decorative stitches are mainly made by using thicker thread in the upper looper.

Below is the 3-thread stitch, using one needle and both loopers.
Left needle for a wider stitch (often used on heavier materials,
right needle for a narrower stitch (often used on lighter materials).
It is important to remove the other needle and thread.
Used for seam finishing.
3 thread stitch

My basic machine has a couple more stitches based on the right needle 3-thread set-up.
Remove the ‘stitch finger’ which holds the thread from pulling in, so you get an even narrower stitch.
A ‘rolled hem’ is made by also increasing the tension of the lower looper thread.

2-thread stitching uses one needle and the lower looper. Not available on all machines. The converter takes the upper looper out of use. Used in various ways, see Threads article.

Many other stitches explained in the Threads post.
5-thread machines have more options for special stitches.


Most modern serger/ overlockers use the same needles as domestic sewing machines. As you will probably be using this machine both for finishing seam allowances on woven fabrics and for making whole garments in knit fabrics, use Universal needles so you don’t have to keep changing needles.
But do check the manual, as some machines use special overlocker needles. These come in different lengths and shapes. It is essential to use the right ones if your machine is set up for them. The wrong shape needles will not hold firmly in the needle holder, and too long ones can cause much damage !

Thread and thread colours

It’s not necessary to use stretch thread when sewing knit fabrics using a serger/ overlocker, as the stretch is in the stitch.
But you could choose to use stretch thread in the loopers as it’s softer.
“Wooly nylon” is also softer, and thicker so the result is bulky, recommended for babies and children.
Polyester thread has a little natural stretch and is stronger than cotton.

You can use regular spools of thread, but as overlocking uses a lot of thread it’s best to use cones of thread, at least for the loopers. Serger/ overlocker thread may be thinner and weaker than conventional machine thread. So you can use conventional machine thread in a serger/ overlocker, but not the other way round !

Seams : The one thread that might show a little on the right side of your make when you sew seams is the left needle thread. So that is the only thread which needs to be a fairly close match to the colour of your fabric.
Seam finishing : All threads are inside the garment and not likely to seen, except when you take off an unlined jacket or coat. So many people use only a few neutral or favourite colours for seam finishing. Unless you become an enthusiast for these machines, or you like the inside of your garment to look as good as the outside, you don’t need 4 cones each of all possible colours !

‘Couture’ overlocked seam finish

I confess I don’t like the look of the conventional 4-thread overlocker stitch used as a seam finish, even though it’s much used in RTW.

There is a less visible way of making a seam finish.
Personalised clothes from couture companies may be made all by hand, but couture companies do use machine overlocking on their RTW clothes (see this post from Cloning Couture).
For overlocking they use a narrow (right needle) 3-thread stitch and very thin semi-transparent thread, so the stitches are nearly invisible.
The thread used is Gutermann U81 Skala 360 (Skala 240 and 200 are thicker).
This thread is also good for blind hemming (uses a special presser foot, this thread makes this stitching even more invisible). And can be used for overlocked seams in lightweight fabrics.

US sources of this thread : Oshman Brothers (search Skala), Wawak.
UK source : William Gee (click under cones photo for colour numbers).


The easiest way to re-thread is the tying on method. Here’s a photo tutorial from Sarah Kirsten.
A reef/ square knot is more difficult to tie than an overhand knot but smaller. In my test, a reef/square knot would go through the eye of a needle, but an overhand knot would not.

Complete threading
If a thread breaks or you want to use thicker threads such as decorative ones, you do need to know how to thread from scratch.

Threading order
Serger/overlockers have to be threaded in a particular sequence, so the threads lead correctly relative to each other.
If you’re a ‘jump in and have a go’ sort of person and usually ignore instructions, threading a serger/overlocker is one area of life where it’s best to attend carefully !

If you can move the cutting blade on your machine, moving it out of the way while threading makes one less thing for the thread to get caught up on.

Threading the loopers
Threading sequence

I have seen a class, which is otherwise good, say you must thread the upper looper first. Mine needs the lower looper threaded first. So do check with the manual and/or find a good clear video for your specific model.
For an example, imagine the thread leads are numbered 1,2,3,4 from left to right – some machines thread 4,3,2,1, some thread 3,4,1,2, and other variations.
If the order isn’t labelled on your machine, put stickers on it to remind you.

Follow the coloured dots marking the thread guides, and thread the hole at the end of a looper from front to back.
You may need to notice details. For example, on my machine the aid to threading the lower looper only works when the needles are in the highest position.

Threading the holes at the ends of the loopers
Videos show the user putting the thread through the hole by hand, then pulling the thread through with tweezers.
As I have shaky hands, that is not helpful advice for me.
A simple solution : put the looper thread into the hole of a hand sewing needle (I use Clover self-threading needles). I find it best to thread the needle before putting the thread through all the leads, as the movements of threading the needle can move the thread out of place.
upper looper : simply pass the hand-needle through the hole at the end of the looper, when the looper is in the top position.
lower looper : only a small needle will go at all through the lower looper hole on my machine, and a small needle (which is shorter) will also go all the way through.

Threading the needles
Similarly with threading the needles – do it in the order instructed. And, like conventional sewing machines : have the presser foot up, and so tension discs open, when threading.

Threading the holes in the needles
Most serger/overlockers do not have needle threaders. But you can use the same ‘pusher’ tool to thread the needles as used on a domestic sewing machine. Beware cheap ones, which are a complete waste of money.

Schmetz self-threading machine needles have a Universal point and come in sizes 80 and 90, so are usable for most projects and fabrics. See this link for advice on when not to use them.

Thread breaks
As threading has to be done in a specific order, if one of the threads breaks, you can’t just re-thread that one thread – it may get tangled around the others. Your machine manual may have special instructions for the re-threading sequence, depending on which thread broke. For example on my machine : if the lower looper thread breaks, all the other threads have to be taken out, and the complete threading sequence gone through in the right order.

Best to practice threading from scratch until it stops being a worry. Hopefully if you’ve chosen a serger/ overlocker with good help with threading loopers, this should stop being alarming quite quickly 👍

Or like me you may get much experience with all the places looper threads can get to, apart from where they’re supposed to be ! Even with an ‘easy threading’ machine, all sorts of odd things can happen. Some thread is ‘springy’, and can get looped and caught around every protrusion – and there are many of those in the looper area ! Threads can get moved out of place while doing a later step in the threading. So after adding each thread, check the previous threads are still in the right place.
Do check that all 4 threads lead correctly and freely before closing the looper access door.

And that springiness is also why it is important to ‘chain off’ when finishing stitching, so the threads are held together and can’t work loose and move around.

Stretching and puckeringdifferential feed
Sometimes when you overlock, the edge of the fabric stretches or puckers, especially with a stretch fabric. Of course there are times when you want that effect. But otherwise, the ‘differential feed’ is the fancy name for the mechanism that solves that problem.
Shorten edge : remove stretches / add puckers : control setting number above 1.
Lengthen edge : remove puckers / add stretches : control setting below 1.
Basically – to make the edge shorter – increase the setting.
(How it works : there are 2 sets of feed dogs, one in front of the needle, one behind. The ‘differential feed’ makes them pull the fabric along at slightly different speeds.)

All that fabric cutting makes a lot of fluff, so clear it out of the looper area frequently. More frequently if using fluffy fabrics or threads. At least after every big project. My machine diverts waste into a scrap catcher, but a lot of little bits fall through to the surface the machine is standing on. Vacuum cleaner and brush are good for different cleaning tasks.

The parts are moving very quickly, so some joints of the upper and lower loopers may need oiling. Use the special fine oil for sewing machines. Some machine brands have their own oilers. See your manual for what needs oiling, where, and how often. Mine needs oiling every one or two weeks, depending how much it is used. Just a small amount, or the oil will get full of fluff, not an effect you want in a crucial area ! The Bernina oiler has a fine tip so it’s easy to apply a single drop, I don’t know about other brands.

I haven’t come across any advice about regularly replacing needles, as is suggested for domestic sewing machines. I have seen a note that needles may break because they are blunt.

Why do they sew more quickly than a conventional sewing machine ?

Several reasons :
– Because serger/ overlockers have 2 sets of feed dogs, they can move fabric at speed.
– Although the loopers use a lot of thread, the thread doesn’t move far during making the stitch. Compare with a domestic machine – on those, to make the lock stitch the top thread has to go down and around the bobbin case.
– Stretch stitches have many parts. Serger/ overlockers have 4 threads, which each contribute a different part of the stitch, so each stretch stitch is made in one move. Compare with a domestic machine which has two threads, and needs multiple needle moves to make one stretch stitch.

Special presser feet
My overlocker model has 5 special presser feet available. I think it’s fairly straightforward how to use the feet for gathering, adding piping, pearls, and elastic, if you’re used to the process on a domestic sewing machine. Do read the manual for any special pointers.
The ‘blind hem’ foot needs the same sort of getting your head around as does the one for a domestic sewing machine.
In this video from Sewing Parts Online the sewist does not use a special presser foot (and you don’t need a big ironing device !).
The special foot makes the process easier, here’s a free video from Craftsy.
This foot can also be used to make pin-tucks. Not made in the same way as using a pin-tuck foot on a domestic sewing machine. It’s more like the way you can make pin-tucks on a sewing machine if you have not got a special pin-tuck foot.

Learning to use one

There are free YouTube videos showing how to use a serger/overlocker, from Sewing Parts Online, 13 short episodes in all, the first one is here.
(The machine used in this demo does not use the same colours as many overlockers. It may be helpful when learning about threading from scratch to use thread colours matching the colour guides on the machine.)

I can understand why people get terrified of these machines. Apart from all the years I took on finding out about these devices, I was far from calm while learning. The videos look as if you can just take one out of the box and go merrily on your way. I’m a careful reader of manuals, but I had a sequence of disasters, every time I tried to do some stitching. Luckily I am a ‘keep trying’ person, as I had a broken looper thread and had to re-thread the loopers in each session. See above as I did not find threading straightforward at first. At least all the stress means I can now do that.

The solution is one of those little things that ‘they’ don’t mention :
when you chain off, keep the threads level with the working surface of the machine, don’t hold/ pull them up in the air – and it’s best to lead the threads straight out to the back.

To stitch around an outer corner, see this video from The Slippy Chicken Company, which also shows the corner turning out method that I like.
If you want to turn a corner and also trim off fabric, then you need this method shown by Sara at Sewing Mastery.

First projects
If you want to do more than finish seam allowances !
Abi’s Den has several easy projects, videos include cutting out instructions, nothing written.
Similar to the first projects suggested for learning to use a domestic sewing machine, see this post.

Not free

Classes for complete beginners :
Beginner Serging from Craftsy.
Sara at Sewing Mastery.
Sew Over It.
Jen Stern at Pattern Review.
Tilly and the Buttons.
I’ve only seen the first, which I found helpful (combined with careful reading of the manual) but have only worked through to using a 4-thread overlock. I can’t comment on the other classes. The Craftsy class does go a bit further than the basics and has 3 projects. The other classes are basic without projects. Which presenter suits you best ?

This course from the former Martha Pullen group of teachers covers techniques beyond the basics, including using some of the special presser feet available.

Marta Alto’s Palmer-Pletsch DVD has good detailed exercises for exploring how to use your serger/ overlocker, such as experimenting with the tension : Sewing with sergers, Basics I and II.

With a conventional sewing machine, you only need to sew straight and zigzag to be able to make clothes. Learning more about your machine is entirely optional, but you can move on to an almost infinite number of ways you can use special needles, presser feet, stitches and threads to make decorative items if you want to.
The same with serger/overlockers – just learn enough to finish woven seams and seam knits, or go on to explore extra presser feet, special stitches, and decorative threads.
Your choice – what would you like to be able to do ?

Most classes mainly teach technique, while I like to learn by making projects.
Deb Canham has two sources of video classes, on making both accessories and garments :
Deb Canham video classes,
Deb Canham video recordings of live on-line classes.

Katrina Walker has two courses with accessory and home dec projects :
a shorter course on the basics, with one project.
And a much more expensive course with 7+ hours of video, which develops skills by making 5+ projects. This course includes an e-book.

Book for garment sewing

The book ‘Simply the Best’ from Simplicity patterns has much information about how to use a serger/ overlocker for nearly all garment sewing processes, Simplicity Simply the Best.

I haven’t tried any books on basic serger/overlocker use, there are so many good videos. Books by Gail Brown and Patti Palmer, and Nancy Zieman, have been recommended.

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Using a serger/ overlocker is not an entirely new world compared to a conventional sewing machine, but there is much to learn.
Good Luck with your own explorations 😀

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Originally written April 2014, links checked September 2022 when I bought my machine.
(That means overlockers worried me so much I spent over 8 years researching before buying one 😀 During the months since then, this post has gone through yet more revisions as I have learned more and more.)

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