Basic Info About Coverstitching, Part 2
Using the BERNINA L 890, the compact overlock/coverstitch combo machine, in a short series of articles I will show you how beautiful stitching seams can be made and will answer important questions about Coverstitching. Part 1 of the series focused on the behavior of the seam when we sew a sweatshirt with a single shirt, so the effect is achieved by changing the tension of the thread. Also, this article is about thread tightening.
We will look at how everything would change if we took two layers of the single shirt. But before that, we’ll take a closer look at the top side of the stitch, at the needle thread.
Needle Thread Photo When Coverstitching
In the photo above, we have two seams that look quite different visually on the side of the needlepoint, but both are stitched with identical thread tension. Why do the seams look so different?
The vertical seam goes with the straight grain of the fabric, and the needle threads sink into the fabric. That’s why you see them less.
A horizontal seam passes through the grain of the fabric. That’s why the stitches can’t sink in but lie on top.
When we sew the cap stitches, usually at the edges, we are sewing through the grain of the fabric. Thus, we have needle threads resting on the fabric. However, we rarely cover the stitches along the grain of the fabric, for example when we cut a bias or grain length for better stretch, when we’re making topstitching or when we’re doing any other things that sewing hobbyists come up with.
Quite often, I read the tips somewhere, in which case you should reduce the tension of the needle thread. However, if the tension of the needle thread is reduced in such a case, the resistance with which the looper thread is pulled on the wrong side to the fabric is also reduced. Thus, the looper is untied and there is a risk that we will no longer find the beautiful cap stitch stitching on the side of the looper. Or everything becomes so loose that it becomes hazy as you relieve more and more stress.
The solution is as simple as it is hidden elsewhere:
Little Helpers: Sticky Washaway
If you’re familiar with embroidery, you’ll know that it washes the fixatives. Avalon for example is a washable stabilizer that you can place over embroidery so that the stitches don’t sink into it. In high-pile fabrics, the thread likes to sink. Then comes the “hair” through embroidery. Even decorative stitches in high pile fabrics, sometimes even in very thick shirts, often get nicer if you add a layer of washing stabilizer on top of the fabric in addition to the embroidery stabilizer underneath.
In our case, we have the same effect. I put a layer of laundry stabilizer on top as I sew when Coverstitching. Usually, I cut the wash into strips, which wait next to the machine. I just put the strips under the foot as required.
Then, when I wash the piece of sewing I’ve finished, the wash is gone, but the seam rests nicely over the material.
why? Because the laundry additionally settled the seam. Thus, the machine was actually forced to insert additional needle thread into the stitches. The stabilizer increases the thickness of the seam, and therefore more needle thread.
By the way, the same applies if we want to better see the side of the lobe, for example, in fabrics with a loose texture. Then simply place the wash away between the fabric and the stitching panel!
Of course, this is also the case that the thread also lengthens when you stretch the seam very hard. It must, otherwise the seam will break. Whether and how the fabric relaxes to its original shape when not stretched is only due to the fabric and the degree of stretch. If the stretch is too strong, the needle thread may also slip between the fabric again and won’t come back to the surface when rested.
By the way, some form of tunnels are created in exactly the same way. If we stretch too hard, the needle and lint threads are stretched. How loosely the looper thread is now depends on the loops of the needle. Again, this depends on the quality of the fabric and its elasticity.
They are often asked – in front of me a hemmed piece of cloth, stretched in double length, why does it cause a tunnel when it is stretched and then when it is loosened again. This is physics, because we sew with threads, not rubber; s).
The amount of thread in the stitch
What do we learn from this? We can’t deal with physics with every tool. If you are stretching too hard, you need enough thread for the entire stretch. No machine, no matter how good it may be, can then conjure up threads from a fabric of poor quality afterwards.
I know some sewing experts think: The better the machine, the less you can do it yourself. In some cases this may work, but the device cannot detect some cases…you are in control.
Let’s get back to the singles shirt experience:
If we look now at the BERNINA L 890 and our final shots from Part 1 of this series, we will find that the tension on the left needle at 5, and on the right needle at 7. Using the annular thread, we partially bypassed the air thread path and the tension was at 0.
If we specify the same settings for our single jersey, the result will look like this:
I’m hesitant about increasing the tension of the needle thread. why? Because then the seam will probably start digging tunnels. Using our knowledge of sewing with stabilizer, let’s add the laundry away. Then we get the following result, without even touching the tension:
You can see it right away – the top seam is the one that is sewn a wash away. why?
On the one hand, we have absolutely no loops on the right needle thread, and the edge of the seam is perfectly smooth. And we have a lot of screw thread in the seam because it lies well between the left and right needle thread. We can now slightly increase the tension of the loop thread or just increase the tension of the left needle. I mean “or”, not “and”. Because if we increase the tension for both, the solenoid thread and the left needle thread, then we have less toroidal thread and less needle thread.
Thus, a tighter needle thread pulls the stronger lubricant thread more into the fabric, creating the potential for tunneling. This is why I always use either or. In such a situation, you must first increase the tension of the annular thread. After sewing test, check the tension of the left needle thread, it may need fine-tuning.
Choosing the right seam for the fabric
In the world of overlocks, the rule is: the softer the fabric, the narrower the stitch, and the stronger the fabric, the wider the stitch may be. You will not sew 7mm wide silk or 3mm wide denim.
There’s no reason this rule shouldn’t apply to Coverstitching either. The finer the fabric, the less it is able to hold large amounts of constant thread, which is formed in wide seams. In two layers of a single jersey, a narrow jacket stitch is definitely better than a wide one—but a wide two-needle layer is still better than a three-needle wide layer. why? In two needles plus loper there are fewer threads than three needles plus loper.
Now I would like to look again at the narrow stitch. If you take out the left needle and use the center and right needle, the machine indicates a 4.5 tension of the center needle, and the right needle has a tension of 6.0. The looper thread is still in the vicinity of the antenna threader, and its tension is at 0.
The upper seam is washed, the lower seam is without:
So, what do we learn from this example? We have three variants of our seam stitch:
- thread tension
- Thread Looper Wrap
- Supporting materials such as washing stabilizer
The alternate “thread-wrap” of the thread can be designated “thread tension/friction”, because the alternate thread-thread path reduces friction, and therefore results in less tension.
The backing material, the stabilizer, keeps the fabric stable and reduces wrinkling or tunneling.
Why is my seam breaking?
In fact, I sometimes read: “I want the seam to be tighter, but somehow it always rips!” Usually this is the norm, that the possible physical limit has been reached.
If I only have 30cm of looped thread in a 10cm seam, how should this seam extend to 40cm?
If I only have a needle thread in a seam of 10cm long and 10cm long, how do I pull the seam down to 20cm? Needle-thread loops and Vs on the side of the loofer are necessary to allow the fabric to be stretched to the maximum.
Of course you can use woolen nylon as an alternative. This is exactly one of the reasons for using worsted nylon: higher elasticity! But even woolen nylon cannot do magic, as one or the other may wish.
This means that the seam is perfect even without washing it with stabilizer. It is wonderfully stretchable. And if there are tunnels because the baby’s head is too big for the narrow opening, I have to pull the seam back into shape afterwards. Because physics doesn’t stop at a child’s head. This is a very good thing.
So far, so good! In the next part, we’ll look at how we can affect elasticity by adjusting stitch length and differential feed.