Working with knitted fabrics often becomes a real challenge for beginning seamstresses, turning the sewing process into a struggle with skipped stitches and wavy seams. Stretch fabrics such as crayons, sweatshirts or jersey require special care, as standard appliance settings are designed for stable, non-stretch materials. Understanding the physics of the interaction of needle, thread and fabric allows you to avoid deformation of the product and get a professional result even with a simple technique.
The main difficulty is that when stretching the fabric, a regular straight stitch does not stretch with it, which leads to the thread breaking during the first fitting. To knitted seam turned out to be strong and elastic, it is necessary to take a comprehensive approach to preparing the equipment, selecting the right consumables and adjusting the tension of the threads. In this article we will look at all the nuances of setting up the machine and sewing techniques.
Selecting a needle and consumables
The foundation of a quality seam on stretch fabric begins with choosing the right needle. Standard needles with a sharp tip simply pierce the fibers of the knitwear, pushing them apart, which often leads to the formation of puffs or even tears in the structure of the material. To work with knitwear and elastane, you must use needles with a rounded tip, which are called Jersey or Stretch.
The rounded tip does not pierce the fibers, but gently pushes them apart, passing between the threads of the fabric, and then compresses them back. This prevents damage to the fabric structure and reduces the risk of skipped stitches. The needle size is selected depending on the density of the material: for thin knitwear, numbers 70-75 are suitable, and for thick footer or jersey it is better to take 90-100.
The choice of thread is no less important. Synthetic threads made from 100% polyester have good elasticity and strength, which is ideal for knitwear. Cotton threads can break when the seam is stretched, so their use is not recommended for basic joining seams. It is also worth paying attention to the lower thread: it should be wound evenly and without knots.
- 🧵 Use needles with markings
JorS(Stretch/Jersey) to prevent fiber damage. - 🧶 Give preference to polyester threads that stretch well with the fabric.
- 📏 Change the needle after every 8-10 hours of work or when sewing each new product.
- 🧼 Always install a new needle before working with delicate knitwear.
⚠️ Attention: Never use old, dull needles for knitwear, as even a microscopic burr on the point will tear the thin elastane fibers, leaving visible defects on the front side of the product.
Setting up a sewing machine for stretch fabrics
Before you start cutting, you need to set it up correctly sewing machine. The first step is to adjust the presser foot pressure on the fabric. For knitted fabric, the pressure should be minimal so that the rail does not stretch the fabric as it moves. If your machine allows you to adjust this setting, reduce the value to minimum or set the special mode for stretch fabrics.
The second important parameter is the stitch length. For elastic materials, the optimal length is 2-2.5 mm. A stitch that is too long can cause the seam to “walk” and hold its shape poorly, while a stitch that is too short can perforate the fabric, making the seam stiff and brittle. Balance here is critical to maintaining elasticity.
Upper thread tension also requires attention. Often the standard tension is too strong, causing the seam to bunch up. Try loosening the upper thread tension by making a few test stitches on scraps of fabric. If the loops of the upper thread are visible on the wrong side, then the tension needs to be increased slightly, but this should be done gradually.
Choosing a stitch type for knitwear
Modern sewing machines offer many stitch options, but not all are suitable for knitwear. Classic straight stitch is rarely used and is used only to stabilize non-elastic areas, as it does not stretch. The main working tools are zigzag and special elastic stitches.
The zigzag stitch is a universal option available on any machine. It allows the seam to stretch with the fabric. A narrow zigzag (width 1-1.5 mm) is often used to hem the bottom or process cuts, preventing fraying. Wide zigzag is suitable for joining parts where high elasticity is required.
If your machine has an elastic stitch feature (often indicated by a zipper or an S), be sure to use it. This stitch is a combination of forward and reverse stitches or a complex zigzag that looks like a straight stitch, but has great stretch. This is ideal for shoulder seams and side seams.
- 🔹 Straight stitch: only for non-stretch inserts or stabilization.
- 🔹 Zigzag: width 1.5-2 mm for processing edges and hems.
- 🔹 Elastic stitch: the main choice for connecting cut parts.
- 🔹 Triple straight: creates a durable decorative seam that imitates a flat seam.
⚠️ Attention: Before starting to sew the main product, be sure to perform a test run on a piece of fabric of the same density to check whether the seam “accordion” bunches when stretched.
Sewing technique: how to avoid stretching
Even with a perfectly tuned machine, the result depends on the execution technique. The main mistake that beginners make is putting too much tension on the fabric with their hands while sewing. The fabric should move under the foot solely due to the operation of the rack. Your hands only slightly guide the canvas, without exerting any effort to stretch or compress.
To make the process easier, you can use a special knit foot. It has a Teflon coating or a roller mechanism that ensures uniform advancement of the top layer of fabric. If you don’t have such a foot, you can use a simple life hack: place a strip of thin paper (tracing paper or newspaper) under the fabric, which can be easily removed after sewing.
It is important to monitor the direction of the thread. Knitwear often warps if parts are cut or sewn on the diagonal unnecessarily. When joining pieces, such as shoulder seams, it is recommended to first pin them perpendicular to the cut or baste them so that the fabric does not move during the process.
☑️ Ready to sew knitwear
Use of stabilizing materials
In some cases, especially when working with very thin or highly stretchy knitwear, the use of additional materials becomes necessary. Stabilizers help maintain the shape of the seam and prevent its deformation during wear and washing of the product.
To process the neckline, armholes and shoulder seams, non-woven tape or a special elastic thread are often used. The interlining is glued to the wrong side of the part before stitching, giving it rigidity. The elastic thread is placed along with the seam, allowing it to stretch, but preventing it from stretching too much and losing its shape.
The table below will help you navigate the choice of stabilizing materials for different types of work:
Dublerin on a woven basis| Part type | Stabilization material | Purpose of use |
|---|---|---|
| Shoulder seam | Non-woven tape or braid | Preventing seam stretching under the weight of the product |
| Neck | Maintain cutout shape, prevent deformation | |
| Bottom of the product (hem) | Elastic thread (spandex) | Creating a flexible but smooth edge |
| Loops on knitwear | Interlining + stabilizing lining | Fixing the shape of the loop, preventing fraying |
Instead of expensive non-woven tape, to stabilize the shoulder seam, you can use a narrow strip cut from the same jersey, but cut across the direction of greatest stretch.
WTO and final processing of seams
Wet heat treatment (WHT) is the final stage that turns amateur work into professional work. Knitted seams must be ironed or ironed immediately after stitching, while the fabric still retains heat from the friction of the needle. This helps to “remember” the desired position of the fibers and straighten the seam.
To iron knitwear, be sure to use the “steam” mode and the steam function. Iron movements should be progressive, without strong pressure, so as not to deform the texture of the fabric. If the fabric contains synthetics, make sure that the heating temperature of the soleplate of the iron meets the requirements of the fabric manufacturer.
Pay special attention to seam allowances. On knitwear they are rarely ironed in different directions, as on woven materials. Most often, seam allowances are ironed to one side (usually to the back or down) and stitched so that they do not turn right side out. This also adds strength to the seam.
What to do if the seam still ripples?
If, despite all the settings, the seam turns out wavy, try steaming it with strong tension. Gently stretch the fabric with your hands along the seam and steam it, then let it cool without letting go. In some cases, lightly sprinkling with a starch solution before drying helps.
⚠️ Attention: Do not iron knitwear in the cross direction with strong pressure, as this can irrevocably stretch the product in width and it will lose its original shape.
Common problems and ways to solve them
Even experienced craftswomen face difficulties when working with capricious fabrics. Understanding the causes of defects allows you to quickly eliminate them. Below are the most common problems and methods to solve them.
If the needle skips stitches, check that it is inserted correctly (with the bulb towards the back wall or according to the machine instructions) and that it matches the type of fabric. Skips can also occur due to the handwheel turning too quickly - try sewing more slowly, using your presser foot to help advance the fabric.
Gathering of fabric under the presser foot often indicates that the upper thread tension is too tight or the presser foot pressure is too high. Loosen the controls and check the result. If the fabric, on the contrary, stretches, the rack may be working too aggressively - reduce the stitch length or add paper.
90% of problems with knitwear are solved by replacing the needle with a specialized one and reducing the pressure of the presser foot on the fabric.
Questions and answers (FAQ)
Is it possible to sew knitwear using a regular straight stitch?
Technically it is possible, but such a seam will not be elastic. When the product is tensioned, the thread will burst, since it will not be able to stretch with the fabric. Straight stitch is used only with elastic thread or for decorative purposes on non-stretchable areas.
What is the difference between a knitting needle and a jeans needle?
The Denim needle has a very sharp and durable point designed to pierce dense woven fibers. The Jersey/Stretch needle has a rounded tip that pulls stitches apart without tearing.
Why does the bobbin thread get tangled when sewing knitwear?
This often occurs due to incorrect threading of the upper thread (not caught between the tension discs) or the use of poor quality threads. The reason may also be that the upper thread tension is too weak.
Do I need to change the foot for sewing knitwear?
Preferred, but not required. A special Teflon-coated foot or roller improves fabric advancement. However, you can sew successfully with a standard foot if you use the technique of placing paper or tape under the fabric.
What stitch length should I choose for a thin knit?
For thin knits such as knitwear, the optimal stitch length is 2-2.5 mm. Increasing the stitch length may cause the seam to appear loose, while decreasing it may cause the fabric to perforate.