Coverstitch 101: a Q and A with Bernina | The Button Jar
Julie Veck, Bernina’s National Product Educator, has been kind enough to answer some of my questions about coverstitchers! This little question and answer between us looks at some of the very basic questions about these machines. I’ve also included a bibliography at the end with links to other websites that have more useful information.
BBB: So this really is starting with the basics, but what is a coverstitch?
Julie: A coverstitch is a separate machine from an overlocker (or serger) machine. It gives a professional hem for garments, a flat seam, which is great for babies garments and a chain stitch for a durable seam (although you have to make sure the chain stitch is tied off correctly).
A coverstitch is also known as a coverseam. Coverstitchers and overlockers belong to the serger family of sewing machines.
BBB: Oh, can you please describe a flat seam for me, as opposed to a flat-felled seam? I haven’t heard of them before.
To make a flat seam on the coverstitch you have two layers of fabric both right sides up and you are joining and topstitching in one step. The raw edges are covered by the stitch.
A flat-felled seam is a two-step seam done on a sewing machine, like on the inside leg of your jeans. The raw edges are encased.
BBB: Oh cool, thanks for that! When is it worth it for a home sewist to get a coverstitch?
J: This is a difficult one to answer for everyone, but it’s not something that you need at the beginning of your sewing journey. When you see in yourself that you’re committed to sewing and this will be a big part of your life then it’s worth looking into. You might start to feel that the finishing on your hems just doesn’t look professional, and having a coverstitch will solve this. It is so much easier for stretch fabrics, as it neatly covers the raw edge at the back and gives your two or three rows of neat stitching on the front
BBB: Ah! I guess they’re so named ‘cover’ stitches because they cover the hem. But why can't I just use a twin needle on my sewing machine?
J: You can, but a twin will give you a zigzag on the back, rather than the two or three thread cover over the raw edge. The twin needle sewing is more of a decorative stitch than a structural stitch, and doesn't have the same ability as a coverstitch to stretch with a knit fabric, making it more likely your stitches will break: if you’ve ever heard the pop of a thread while pulling a twin-needle stitched jumper over your head, you’ll know what I mean. The twin-needle can also cause problems with ‘tunnelling’—where the tension of the zigzag is too tight, causing the fabric between the twins to bulge like a tunnel.
BBB: So when would I use a one needle stitch, a two needle stitch and a three needle stitch? And what about a narrow stitch versus a wide stitch? —Is that just aesthetic or is it function?
J: The one-needle will give you a chain stitch. A two-needle stitch is good for finer fabrics, and will keep the fabric from tunnelling as you see with the twin needles. And a three-needle stitch is good for sturdier or thicker fabrics. However, it does also depend on the final look that the sewist desires, so these are just guidelines.
BBB: Um, what is the chain stitch for, exactly?
J: When it’s properly knotted it will give you a strong, durable stitch. You can see chain stitching on various parts of ready-to-wear jeans. But it can also function as a basting stitch, as it is easily undone, or even as decorative stitching.
BBB: Oh, good to know. So can you use it for wovens as well as knits?
J: When used with the correct needles, you can use a coverstitch for all types of fabrics, from crepe and tricot to denim, corduroy and jersey.
BBB: This is a question from Instagram: I want to do topstitching on stretch jeans; can you get over really thick seams with a coverstitch?
J: Yes, depending how thick your fabric is, but you will have to test sew first. It can be difficult to get over the thicker bumps of fabric. There are suggestions that you can hand-crank over thick seams, which is okay as long as it’s only for a few stitches. We don’t recommend doing this over a long seam.
BBB: I’m making some jeans at the moment so I’ve been paying a lot of attention to my last (dying) pair of RTWs, and there is a huge amount of chain stitching in them, so I too have been playing with my coverstitcher for jeans-making—something I didn’t anticipate when I first got it! And another question from Instagram: can you use the chain-stitch for sewing up toiles?
J: Yes, providing you knot the chain-stitch correctly or it will unravel.
BBB: So, do I need to buy three or four spools of thread? It feels like I have to buy a lot of thread, but might not use it all.
J: Depending on whether you’re using a two or three needle coverstitch, you will need up to four spools of threads. However, you can get away with using loaded bobbins, which can reduce the amount of thread spools you need to buy.
BBB: I often see a lot of fear about CS machines online. Why are people scared of CS machines? What puts people off using them?
J: The main thing that concerns people are the threading and also figuring out tensions, but these days the cover stitch machines are not so scary.
BBB: Yes, I know what you mean! Threading up the coverstitch is a lot simpler that threading up an overlocker. So what are the main causes for skipped stitches?
J: Usually, it’s not using the correct needle for the fabric or the needle is blunt. So it’s worth investing in coverstitch needles at the size appropriate for the fabric you’re using, and change your needle frequently.
BBB: I find the Fabric, Thread and Needle Chart in the instruction manual is very helpful when working out which needles. But I’m curious, why is it important to use specifically designed CS needles?
J: It’s all to do with the shape of the needles, the front, back and point. They’re designed for the specific motion of coverstitching, which is different to overlocking and sewing.
BBB: There’s an excellent description of the parts of needles in general on Episode 37 of the Love to Sew podcast that I found fascinating! For such little things they are very complex. And there are different needles for coverstitching wovens vs coverstitching knits?
J: Yes, just as with your sewing machine and overlocker, you need to use the correct needle for the fabric. For example, if you sew your stretch garment together with a sharp needle it will cut all of the stretch and your garment will eventually ladder or fall to bits. Bernina has two coverstitching needles: there’s ELX705 SUK for knit fabrics, and ELX705 CF for woven fabrics.
BBB: This is another from Instagram: testing stitches takes forever! I would love recommended settings for different fabrics to use as a starting point when testing.
J: Unfortunately with a combination of needles, threads, fabrics, stitch length, 1 2 or 3 needles and differential feed, it is difficult to give a starting point, testing is the only way. However, there is useful information in the instruction manual to help guide you, and lots of patient practice will give you the feel for the coverstitch to speed this process up.
BBB: Learning a sense for these sorts of machines does take time, but I’ve starting keeping a notebook where I staple a swatch of the fabric, and note the tensions and settings that I’m happy with for that fabric. It, at least, gives me a starting point for when I’m testing a new fabric. So do you have any other top tips?
J: Yes, learn the difference about needles as they play a big part in sewing all fabrics on all machines.
Also I’d suggest using the same brand thread across the machine. With different brands having different makeups, mixing threads can cause tension issues.
And finally the differential feed is a sewist’s best friend when stitching stretch fabric: no more wavy seams or hems!
BBB: Thank you so much, Julie for taking the time to answer these questions!
If you want further information on coverstitchers, here’s some websites I’ve found useful:
This article from Seamwork, A Guide to Coverstitch Machines, is a great overview with some useful general instructions and a troubleshooting section.
I’m planning on taking this Craftsy class, Coverstitch, Basics and Beyond, to help up my coverstitch game.
If you fancy nerding out on needles, have a listen to Episode 37 of Love to Sew, or check out How to Choose Sewing Machine Needles on Craftsy. This diagramme, from the SCHMETZ website, shows how coverstitch needles are different from universals (note the extra groove down the front of the needle.
And for the uber-nerds out there who want to fully immerse themselves in all the technical details, here’s the patent for the coverstitch machine: US7111568B1.
As a teaser, here’s the abstract:
In a cover stitch sewing machine which forms double chain stitch seams, needle threads are pulled out from the needle thread tensioning devices, passing over a thread hanging point on a needle thread pulling-up spring and the needle thread take-up completes drawing-up of the needle threads after needle thread loops of the respective needles are seized by the looper. The sewing material is then fed one feed pitch as the needles are moved down and the needle thread take-up draws out the needle threads, while the needle threads are pulled up at the thread hanging point by the elasticity of the needle thread pulling-up spring, thus preventing slack in the needle threads below the needle thread eyes. The threads which are connected with the needle thread loops, are drawn up by the thread hanging point of the needle thread take-up against the resiliency of the needle thread pulling-up spring.”